03hb002.txt

Handbook for 
Computer Security 
Incident Response 
Teams (CSIRTs) 
 
 
Moira J. West-Brown 
Don Stikvoort 
Klaus-Peter Kossakowski 
Georgia Killcrece 
Robin Ruefle 
Mark Zajicek 
 
 

First release: December 1998 
2nd Edition: April 2003 

 

 

 

 

 

 

 

 

 

HANDBOOK 
CMU/SEI-2003-HB-002 
 

 

 

Pittsburgh, PA 15213-3890 

Handbook for 
Computer Security 
Incident Response 
Teams (CSIRTs) 
 
 
CMU/SEI-2003-HB-002 
 
 
 
Moira J. West-Brown 
Don Stikvoort 
Klaus-Peter Kossakowski 
Georgia Killcrece 
Robin Ruefle 
Mark Zajicek 
 

First release: December 1998 
2nd Edition: April 2003 

 
Networked Systems Survivability Program 

Unlimited distribution subject to the copyright. 

The original version of this handbook was provided with funding from the following organizations: 

U.S. National Science Foundation (NSF); 
SURFnet bv; 
SURFnet ExpertiseCentrum bv; 
M&I/STELVIO bv; 
German  Federal  Ministry  of  Education,  Science,  Research  and  Technology  (Bundesministerium  fuer  Bildung, 
Wissenschaft, Forschung und Technologie); 
Verein zur Foerderung eines Deutschen Forschungsnetzes e.V. (DFN-Verein). 

Funding for the revised edition of this handbook was provided by the Software Engineering Institute. 

This report was prepared for the 

SEI Joint Program Office 
HQ ESC/DIB 
5 Eglin Street 
Hanscom AFB, MA 01731-2116 

The ideas and findings in this report should not be construed as an official DoD position. It is published in the 
interest of scientific and technical information exchange. 

FOR THE COMMANDER 

 

Christos Scondras 
Chief of Programs, XPK 

This work is sponsored by the U.S. Department of Defense. The Software Engineering Institute is a  
federally funded research and development center sponsored by the U.S. Department of Defense. 

Copyright 2003 by Carnegie Mellon University. 

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Table of Contents 

Preface to the Second Edition ...............................................................................ix 

Preface to the First Edition ....................................................................................xi 

Acknowledgements ..............................................................................................xiii 

Abstract..................................................................................................................xv 

1 

2 

Introduction .....................................................................................................1 
1.1  Scope of the Document .............................................................................4 
1.2 
Intended Audience.....................................................................................5 
1.3  Use of This Document ...............................................................................6 
1.4  Document Structure...................................................................................7 

Basic Issues.....................................................................................................9 
2.1  CSIRT Framework.....................................................................................9 
2.1.1  Mission Statement .......................................................................10 
2.1.2  Constituency ................................................................................11 
2.1.3  Place in Organization...................................................................17 
2.1.4  Relationship to Other Teams .......................................................19 
2.2  Service and Quality Framework...............................................................21 
2.3  CSIRT Services .......................................................................................23 
2.3.1  Service Categories.......................................................................24 
2.3.2  Service Descriptions ....................................................................25 
2.3.3  Selection of Services ...................................................................34 
Information Flow......................................................................................35 
2.4 
2.5  Policies....................................................................................................38 
2.5.1  Attributes .....................................................................................39 
2.5.2  Content ........................................................................................40 
2.5.3  Validation.....................................................................................41 
2.5.4 
Implementation, Maintenance, and Enforcement .........................42 
2.6  Quality Assurance ...................................................................................42 
2.6.1  Definition of a Quality System ......................................................43 
2.6.2  Checks: Measurement of Quality Parameters ..............................45 

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3 

2.6.3  Balances: Procedures to Assure Quality...................................... 47 
2.6.4  Constituents View of Quality ....................................................... 48 
2.7  Adapting to Specific Needs ..................................................................... 48 
2.7.1  The Need for Flexibility................................................................ 50 
2.7.2  Legal Issues ................................................................................ 51 
Institutional Regulations .............................................................. 58 
2.7.3 

Incident Handling Service ............................................................................ 61 
3.1  Service Description ................................................................................. 61 
3.1.1  Objective ..................................................................................... 62 
3.1.2  Definition ..................................................................................... 63 
3.1.3  Function Descriptions .................................................................. 64 
3.1.4  Availability ................................................................................... 65 
3.1.5  Quality Assurance ....................................................................... 65 
3.1.6 
Interactions and Information Disclosure....................................... 66 
3.1.7 
Interfaces with Other Services..................................................... 66 
3.1.8  Priority......................................................................................... 66 
3.2  Service Functions Overview.................................................................... 67 
3.3  Triage Function ....................................................................................... 69 
3.3.1  Use of Tracking Numbers ............................................................ 70 
3.3.2  Use of Standard Reporting Forms ............................................... 73 
3.3.3  Preregistration of Contact Information ......................................... 75 
3.4  Handling Function ................................................................................... 76 
Incident Life Cycle ....................................................................... 77 
3.4.1 
3.4.2 
Incident Analysis ......................................................................... 79 
3.4.3  Tracking of Incident Information................................................... 91 
3.5  Announcement Function ......................................................................... 92 
3.5.1  Announcement Types.................................................................. 93 
3.5.2  A Priori Considerations................................................................ 95 
3.5.3  Announcement Life Cycle............................................................ 97 
3.6  Feedback Function ............................................................................... 100 
Interactions ........................................................................................... 102 
3.7 
3.7.1  Points of Contact ....................................................................... 103 
3.7.2  Authentication............................................................................ 106 
3.7.3  Secure Communication ............................................................. 109 
3.7.4  Special Considerations.............................................................. 110 
Information Handling..............................................................................119 
Information Collection................................................................ 119 
3.8.1 
Information Verification.............................................................. 120 
3.8.2 
3.8.3 
Information Categorization......................................................... 121 
Information Storage................................................................... 122 
3.8.4 
3.8.5 
Information Sanitizing and Disposal........................................... 123 

3.8 

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3.8.6  Prioritization Criteria...................................................................124 
3.8.7  Escalation Criteria......................................................................128 
Information Disclosure ...............................................................132 
3.8.8 

Team Operations .........................................................................................137 
4.2  Fundamental Policies ............................................................................141 
4.2.1  Code of Conduct........................................................................141 
4.2.2 
Information Categorization Policy...............................................143 
4.2.3 
Information Disclosure Policy.....................................................144 
4.2.4  Media Policy ..............................................................................148 
4.2.5  Security Policy ...........................................................................149 
4.2.6  Human Error Policy....................................................................150 
4.3  Continuity Assurance.............................................................................151 
4.3.1  Continuity Threats......................................................................152 
4.3.2  Workflow Management ..............................................................155 
4.3.3  Out-Of-Hours Coverage.............................................................157 
4.3.4  Off-Site Coverage ......................................................................159 
4.4  Security Management............................................................................159 
4.5  Staff Issues............................................................................................166 
4.5.1  CSIRT Staff................................................................................167 
4.5.2  Hiring Staff.................................................................................169 
4.5.3  Arrival and Exit Procedures........................................................171 
4.5.4  Training Staff .............................................................................172 
4.5.5  Retaining Staff ...........................................................................174 
4.5.6  Extension of Staff.......................................................................175 

5 

Closing Remarks .........................................................................................177 
5.1  Closing Remarks from the First Edition..................................................177 
5.2  Closing Remarks for the Second Edition ...............................................178 

Appendix A:  About the Authors ........................................................................181 

Appendix B:  Glossary........................................................................................187 

Bibliography.........................................................................................................193 

 

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List of Figures 

Figure 1:  CSIRT Within an Organization ..............................................................18 

Figure 2:  CSIRT Peer Relationships.....................................................................21 

Figure 3:  Service and Quality Framework as Derived from Mission Statement.....22 

Figure 4: 

Incident Handling Service Functions .....................................................67 

Figure 5:  CERT/CC Incident Handling Life Cycle .................................................77 

Figure 6:  CERT/CC Code of Conduct.................................................................143 

 

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List of Tables 

Table 1: 

Examples of CSIRT Types With Associated Missions and Constituencies12 

Table 2: 

Possible Authority Relationships Between a CSIRT and Its Constituency15 

Table 3: 

Service Description Attributes................................................................23 

Table 4: 

List of Common CSIRT Services ...........................................................25 

Table 5: 

Examples of Possible Information Flow to and from the Incident Handling 
Service..................................................................................................37 

Table 6: 

Basic Policy Attributes...........................................................................40 

Table 7: 

Policy Content Features ........................................................................41 

Table 8: 

Examples of Dynamic Environment Factors and Their Impact on CSIRTs50 

Table 9: 

Examples of Liability Issues Arising From Omission..............................56 

Table 10:  Examples of Liability Issues Arising From the Content of Signed 

Contracts...............................................................................................56 

Table 11:  Examples of Liability Issues Arising From Information Disclosure .........57 

Table 12:  Range of Possible Incident Handling Service Objectives Based on 

Differing Team Types.............................................................................62 

Table 13:  Possible Instantiations of Handling Function Attributes..........................76 

Table 14:  Analysis Depth Factors .........................................................................82 

Table 15:  Notable Characteristics of Log Files ......................................................83 

Table 16: 

Incident Tracking Information ................................................................91 

Table 17:  Possible Inter-Team Support Types..................................................... 113 

Table 18:  Considerations for Information Sharing ............................................... 113 

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CMU/SEI-2003-HB-002 

Preface to the Second Edition 

We have often been asked whether an updated version of the CSIRT Handbook would ever 
be released. Periodically we have reviewed the document and found that most of the material 
and guidance provided are still current, relevant, and helpful to new and existing teams. Some 
of the examples included and organizations discussed were dated, but otherwise the concepts 
and recommendations covered are still valid for todays work. 

In the summer of 2002, the CERT CSIRT Development Team began collaboration with the 
Trusted Introducer for European Computer Security Incident Response Teams (CSIRTs) 
service to create a standard set of service descriptions for CSIRT functions. As we finished 
that document1 it became apparent that we should, indeed, update the CSIRT Handbook to 
include this new list of services. As we began to revise the document we felt it was also time 
to update any out-of-date examples and also any out-of-date terminology. We also included, 
where appropriate, references to new discussion topics, resources, or CSIRT operational 
activities that we believe are relevant to the information discussed in this handbook. 

In the long run though, we elected to minimize the changes to the original as much as 
possible. These are the main changes that have been made: 

1.  Many of the examples provided in the handbook have been updated. We have kept a 
number of the previous examples, as they are still true conceptually and the guidance 
available still proves to be useful today. More recent examples have been added that we 
hope will be more applicable for todays readers. 

2.  The new CSIRT service definitions have been incorporated throughout the handbook. 

3.  The handbook has been aligned with other new documents that we have produced or are 

in the process of producing, specifically the new Organizational Models for CSIRTs 
handbook. This document is a companion piece to the CSIRT Handbook. It provides 
detailed information on the types of organizational structures and corresponding services 
that may be implemented to provide a CSIRT capability. We have timed the release of 
this updated version of the CSIRT Handbook with the publication of the Organizational 
Models for CSIRTs handbook. 

As stated in the original CSIRT Handbook preface: We can learn from the experiences of 
others and we do this every day. So if you have comments on this version, if you want to 

                                                 
1   The list of services is available at http://www.cert.org/csirts/services.html. 

CMU/SEI-2003-HB-002 

ix 

share your opinions, or if you have other suggested additions, please contact us. We regularly 
attend FIRST Conferences and other CSIRT events, and we can be contacted in person or 
reached as a group by sending email to the following address: csirt-handbook@cert.org. 

 

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Preface to the First Edition 

The number of computer security incident response teams (CSIRTs) continues to grow as 
organizations respond to the need to be better prepared to address and prevent computer 
security incidents. Just as computer science has struggled to be recognized as a scientific field 
in its own right, computer security has struggled to be recognized as an essential component 
of computer science. Similarly, the need for CSIRTs should be recognized within the security 
arena. As new teams have attempted to form, they have faced the hurdles of having to justify 
the need for their existence and gaining support and understanding of the problems that they 
are trying to address. If they have managed to overcome those hurdles, then they have had an 
additional challenge to face: the lack of documented information on how to effectively form 
and operate a CSIRT and gain recognition for it. So the need for a handbook of this type is 
long overdue. 

The idea to write this handbook resulted from an email discussion between the original 
authors (West-Brown, Stikvoort, and Kossakowski) in the summer of 1996. At that time the 
authors were each working on similar projects in their own organizations: helping other 
CSIRTs form and develop corresponding policies and procedures. The authors saw a growing 
demand from newly forming teams for help and assistance in their formation and operation 
and realized that there were insufficient experts available to fulfill this growing demand. 
Because the task of forming and operating a CSIRT is fraught with pitfalls that can result in 
the demise of a team, it was clear that to ensure an infrastructure of competent and respected 
CSIRTs, supporting information and guidance would be imperative for success. 

As with many projects of this type, the handbook development has taken longer than was 
originally anticipated; it has been something that weve tried to work on when we had spare 
time. Given that the field in which we work is so dynamic and demanding and experts are in 
short supply, that spare time has generally been carved from late nights and weekends. We 
had the luxury of spending most of a week in October 1996 together devoted to scoping the 
handbook, which resulted in a 22-page structured outline of the issues. With that foundation 
in place, we returned to our own organizations and began the slow process of writing the 
content of the various sections and continued document development. 

We hope that you will find this resulting first edition a useful reference document in the 
formation, management, and operation of your CSIRT. We have based material in this 
handbook on our experiences in forming and operating our own organizations CSIRTs and 
through assisting other CSIRTs in their formation and operation. 

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CMU/SEI-2003-HB-002 

Acknowledgements 

We have many people to thank for contributions that made the original handbook possible. 
First our thanks go to the CERT Coordination Center (CERT/CC), Verein zur Foerderung 
eines Deutschen Forschungsnetzes e.V. (DFN-Verein), M&I/STELVIO, U.S. National 
Science Foundation (NSF), SURFnet ExpertiseCentrum bv, and SURFnet bv. These 
organizations supported this effort through funding, allowed us to spend time and resources 
on this project, and gave us the opportunity to gain experience and flourish in this field. 
Special thanks go to our colleagues at CERT/CC, CERT-NL, and DFN-CERT who were busy 
handling incidents and addressing computer security emergencies at times when we were 
working on deadlines for this project. 

Our thanks also go to the organizations that have sought our help in forming and operating 
their CSIRTs. Addressing their probing questions and having them share their differing needs 
and situations with us has enabled us to obtain a more rounded view of the field and has 
broadened the scope of our experience. 

We sought technical review of the first draft of this document from a variety of individuals. 
We selected a cross section of reviewers ranging from those we knew were interested in 
forming a CSIRT and were new to the field of computer security, to those who have 
considerable operational experience from a technical or management perspective. Knowing 
how busy such people are, we selected 15 reviewers in the hope that maybe 8 would have the 
opportunity to read the draft and provide feedback in the short time available. To our 
amazement, 14 of the reviewers provided us with feedback of some sort. The 15th reviewer 
sent his apologies explaining that he was unavailable due to illness. Our thanks go to all the 
reviewers who found time to comment on the first draft of this handbook (affiliations shown 
are from the time of the first edition): 

David Finch (MOREnet)  
Eduardo Garcia (Price-Waterhouse)  
John Horton (DANTE)  
Erik Huizer (SURFnet ExpertiseCentrum bv)  
Larry J. Hughes, Jr. (NorthWestNet)  
Georgia Killcrece (CERT/CC)  
Kathleen Kimball (Pennsylvania State University)  
Wolfgang Ley (DFN-CERT)  
                                                 
 CERT is registered in the U.S. Patent and Trademark Office. 

CMU/SEI-2003-HB-002 

xiii 

Hannes P. Lubich (SWITCH-CERT)  
Jorgen Bo Madsen (NORDUnet CERT)  
Ken McNulty (SEI)  
Maj. Byron Thatcher (AFIWC/AFCERT)  
Wietse Venema (IBM)  
Mark Zajicek (CERT/CC) 

We would particularly like to acknowledge the efforts of Larry J. Hughes, Jr., Georgia 
Killcrece, Wolfgang Ley, Hannes P. Lubich, and Jorgen Bo Madsen who all went above and 
beyond the call of duty by providing very extensive and detailed comments. 

The first draft of this document was an interesting work written by three authors with 
differing native tongues. The task of taking that draft and generating a document ready for 
technical review was placed on the shoulders of Bill McSteen (a technical writer/editor at the 
SEI). Bill did an excellent job of smoothing over the bumps in the flow of the document so 
that the reviewers were able to focus on technical and structural comments. Bills continued 
effort was as essential to provide the final version of this document. 

Our thanks for this second edition go to Pamela Curtis, also a technical writer/editor at the 
SEI, without whose expert help this task would have been much more difficult to accomplish. 
Her technical and editorial assistance helped tremendously and enabled the authors to focus 
on the content of the material.  

We would also like to extend heartfelt thanks to our Technical Manager, Dr. Barbara Laswell, 
who encouraged us to revise the Handbook and who generously provided the resources and 
time for us to devote to this revised text. 

Finally, we would like to thank our families. Without their support, understanding, and 
encouragement, none of us would have been able to complete our portions of this work nor 
would we have found it an enjoyable exercise. 

 

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CMU/SEI-2003-HB-002 

Abstract 

This document provides guidance on forming and operating a computer security incident 
response team (CSIRT). In particular, it helps an organization to define and document the 
nature and scope of a computer security incident handling service, which is the core service 
of a CSIRT. The document explains the functions that make up the service; how those 
functions interrelate; and the tools, procedures, and roles necessary to implement the service. 
This document also describes how CSIRTs interact with other organizations and how to 
handle sensitive information. In addition, operational and technical issues are covered, such 
as equipment, security, and staffing considerations. 

This document is intended to provide a valuable resource to both newly forming teams and 
existing teams whose services, policies, and procedures are not clearly defined or 
documented. The primary audience for this document is managers who are responsible for 
the creation or operation of a CSIRT or an incident handling service. It can also be used as a 
reference for all CSIRT staff, higher level managers, and others who interact with a CSIRT. 

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1  Introduction 

The evolution of the Internet has been widely chronicled. Resulting from a research project 
that established communications among a handful of geographically distributed systems, the 
Internet now covers the globe as a vast collection of networks made up of millions of 
systems.  

The Internet has become one of the most powerful and widely available communications 
mediums on earth, and our reliance on it increases daily. Governments, corporations, banks, 
and schools conduct their day-to-day business over the Internet. With such widespread use, 
the data that resides on and flows across the network varies from banking and securities 
transactions to medical records, proprietary data, and personal correspondence. 

The Internet is easy and cheap to access, but the systems attached to it lack a corresponding 
ease of administration. As a result, many Internet systems are not securely configured. 
Additionally the underlying network protocols that support Internet communication are 
insecure, and few applications make use of the limited security protections that are currently 
available. 

The combination of the data available on the network and the difficulties involved in 
protecting the data securely make Internet systems vulnerable attack targets. It is not 
uncommon to see articles in the media referring to Internet intruder activities.  

But, exploitation of security problems on the Internet is not a new phenomenon. In 1988 the 
Internet Worm incident occurred and resulted in a large percentage of the systems on the 
network at that time being compromised and temporarily placed out of service. Shortly after 
the incident, a meeting was held to identify how to improve response to computer security 
incidents on the Internet. The recommendations resulting from the meeting included a call for 
a single point of contact to be established for Internet security problems that would act as a 
trusted clearinghouse for security information. In response to the recommendations, the 
CERT Coordination Center (also known as the CERT/CC and originally named the 
Computer Emergency Response Team) was formed to provide response to computer security 

                                                 
   CERT is registered in the U.S. Patent and Trademark Office. 

CMU/SEI-2003-HB-002 

1 

incidents on the Internet [CERT/CC 1997b]. The CERT/CC was one of the first organizations 
of this typea computer security incident response team (CSIRT2). 

A CSIRT can most easily be described by analogy with a fire department. In the same way 
that a fire department has an emergency number that you can call if you have or suspect a 
fire, similarly a CSIRT has a number and an email address that you can contact for help if 
you have or suspect a computer security incident. A CSIRT service doesnt necessarily 
provide response by showing up on your doorstep (although some do offer that service); they 
usually conduct their interactions by telephone or via email. 

Another similarity between fire departments and CSIRTs is that responding to emergencies is 
only part of the service provided. Just as important is trying to prevent emergencies from 
occurring in the first place. So just as a fire department offers fire safety education to raise 
awareness and encourage best practices, CSIRTs produce technical documents and undertake 
education and training programs for the same purpose. In the area of improvement, a fire 
department will influence laws to ensure improved safety codes and fire-resistant products. 
Similarly CSIRTs participate in forums to improve baseline security standards. 

When the Internet Worm incident occurred, the size of the network was estimated at 60,000 
hosts; a decade later there were more than 36 million hosts on the Internet and a 
corresponding increase in intruder activity. The January 2003 Internet Domain Survey [ISC 
2003] shows 171.6 million hosts advertised in the Domain Name Service. Clearly a single 
CSIRT is unable to effectively serve such a vast constituency. In particular a single CSIRT 
wouldnt be able to address the individual needs of the diverse communities that make up the 
Internet due to time zone, language, cultural, and organizational issues. Correspondingly, a 
number of organizations have foreseen the need to be better prepared to respond to intruder 
activity affecting their community [West-Brown 1995]. This has resulted in a surge of interest 
in the formation of CSIRTs. 

Hundreds of CSIRTs around the world have formed since 1988, and they, like newly forming 
CSIRTs today, face many challenges as they strive to become operational. Newly forming 
teams commonly seek guidance and assistance in determining the scope and range of their 
services and in forming their operational policies and procedures [Pethia 1990a, Pethia 
1990b]. When this CSIRT Handbook was originally published in 1998, there were not as 
many resources available to help new teams establish appropriate and reliable services. Today 
                                                 
2   When the first edition of this handbook was published, the term incident response was used to 

describe the core service of a CSIRT (hence the convention for the IR letters in the CSIRT 
acronym). As our understanding of such teams has matured over time, incident response has 
become one component of a much broader incident handling service that encompasses more 
than just response to an event. We have, therefore, adopted the convention of incident handling 
services throughout this handbook (as well as in our other publications [CERT/CC 2002a]). 
However, we still continue to use the acronym CSIRT, since it is a generic description for a 
team and is a term that has been widely adopted by the community. 

2 

 

CMU/SEI-2003-HB-002 

there are many more articles, books, tutorials,3 other documents, and Web resources 
available.4 There are also various organizations, such as the Forum of Incident Response and 
Security Teams (FIRST) and the TERENA-sponsored TF-CSIRT (a task force for the 
collaboration of incident response teams in Europe), who promote collaboration among teams 
and provide resources for helping new and existing teams [TERENA 1995]. The good news 
is that todays newly forming CSIRTs need not fend for themselves (learning only from their 
own experiences or making costly mistakes); they can now leverage the experiences of many 
others to help them develop and implement more effective teams.5,6,7 

Although more information is now available to help organizations build their CSIRT 
capability, unfortunately there is still little available in the area of operational policies and 
procedures, e.g., generic CSIRT policies, procedures, and templates that can be adapted or 
revised for use by newly forming teams. Either existing teams have nothing documented to 
share or they are unable to share their documentation due to its sensitive nature. Seeking 
expert advice is also difficult because there is still a shortage of experts in the field. Existing 
experts are highly sought after, have little time to make available, and can be expensive to 
engage.  

Once operational, the need for well-defined services, policies, and procedures does not 
diminish. Existing CSIRTs lacking clearly defined services commonly suffer from recurring 
operational problems. For example, they rely on their existing staff to pass on their 
operational experience to new staff. All too frequently, the consistency, reliability, and levels 
of service exhibited by such CSIRTs fluctuate dramatically due to the varied perceptions of 
each of the team members. As a consequence, the constituency served by these CSIRTs may 
have a false impression of the services offered, which jeopardizes rapport between a CSIRT 
and its constituency that is essential to the success of the team. Clearly defined and 
documented services will help the team and, more importantly, will provide guidance for the 
teams constituency, enabling them to understand the services offered by the CSIRT and how 
those services should be accessed. 

                                                 
3   The CERT/CC, for example, offers a suite of courses for both CSIRT managers and incident 

handlers. See http://www.cert.org/nav/index_gold.html. 

4   See the CERT CSIRT Development Teams List of Resources for more information: 

http://www.cert.org/csirts/resources.html. 

5   See also the Workshops on Computer Security Incident Handling, Forum of Incident Response 

and Security Teams, 1989-2002. 

6   Sparks, Sandy; Fithen, Katherine; Swanson, Marianne; & Zechman, Pat. Establishing an Incident 

Response Team. Tutorial, 9th Workshop on Computer Security Incident Handling, Forum of 
Incident Response and Security Teams, Bristol, U.K., June 1997. 

7   Stikvoort, Don & Kossakowski, Klaus-Peter. Incident Response Teams: the European 

Perspective.8th Workshop on Computer Security Incident Handling, Forum of Incident Response 
and Security Teams, San Jose, Calif., July 1996. 

CMU/SEI-2003-HB-002 

3 

1.1  Scope of the Document 

This document provides guidance on the generic issues to consider when forming and 
operating a CSIRT. Relating back to our fire department analogy, providing an effective 
service is a complex operation. It can only be a success if it is based on appropriate policies 
and procedures and if it addresses a range of both reactive and proactive issues. A fire 
department can be a volunteer or directly funded operation. The service provided is based on 
available resources and funding. CSIRTs are under the same cost-cutting demands as other 
organizations. So they must constantly make the tradeoff between the range and levels of 
service that they would like to provide and what they can afford to provide. This includes 
identifying the CSIRT services, policies, and procedures appropriate for a given situation. It 
also means identifying those operational issues that must be addressed to implement an 
efficient incident handling capability. 

In particular, this document helps an organization to define and document the nature and 
scope of a computer security incident handling service. To this end, we discuss the functions 
that make up the service; how those functions interrelate; and the tools, procedures, and roles 
necessary to implement the service. We also focus on incident analysis. Just as a fire 
department may investigate a fire to understand how it came about (e.g., act of nature, arson, 
or an electrical design fault), a CSIRT tries to understand how an incident occurred. While a 
fire departments analysis will include sifting through ashes, a CSIRTs will include looking 
at system logs and any files left behind by an intruder. 

A fire department needs to coordinate with other fire departments who it may call (or be 
called) on for reinforcements in times of peak demand or to address a crisis. It must interact 
with other emergency services to respond appropriately and provide law enforcement with 
the information that it legally requires. This document will discuss how CSIRTs interact with 
other organizations, such as the sites that report security problems to it, other CSIRTs, law 
enforcement, and the media. A fire department must handle information, some of which is 
sensitive as it may pertain to the perpetrator of a crime. Similarly a CSIRT must handle 
information appropriately. Most CSIRTs offer client confidentiality in the same way that 
many crisis lines do, shielding the reporters and victims from public disclosure. This topic is 
critical to the survival of a CSIRT, because if it cannot be trusted to handle information 
appropriately, nobody will report to it, rendering the CSIRT almost useless. Consequently, 
information handling is an essential issue of discussion in this handbook. 

Some CSIRTs have dedicated staff while others pull together part-time, volunteer staff and 
trusted security experts to address a given security crisis.8 A CSIRTs staff is its interface with 
the world, and the image that its staff members project through the way they conduct 

                                                 
8   More information about different staffing models will be available in a companion document, 

Organizational Models for CSIRTs, to be published in 2003 on our Web site at 
<http://www/cert.org/csirts/>.  

4 

 

CMU/SEI-2003-HB-002 

themselves, and the quality of service they provide, are paramount to the CSIRTs success. 
Finding appropriately qualified staff can be difficult, since such staff are in great demand. 
However, all too often people responsible for hiring CSIRT staff unknowingly look for the 
wrong set of skills and qualities in potential employees. Consequently we discuss staffing and 
hiring issues and steps that you can take to ensure that CSIRT staff provide a consistent, 
warm, and professional interface for your team. 

A CSIRT may provide a range of other services in addition to the incident handling service, 
such as vulnerability handling and/or the provision of intrusion detection services. Although 
we have included a high-level description of these other services, the specific procedures and 
policies are beyond the scope of this document. 

The material in this document is presented in a form that is suitably generic to enable the 
reader to apply it to any type of CSIRT environment, from a fee-for-service team, to an in-
house team for a given organization, or an international coordination center. 

1.2 

Intended Audience 

While many new CSIRTs have formed and become operational, the increase in the number of 
these teams has not kept pace with Internet growth and intruder activity. Many more 
organizations are recognizing the need for a CSIRT to address their specific needs. 
Anticipating this need, we have targeted this handbook at those individuals who will be most 
heavily involved in the establishment of CSIRTs. 

The primary audience for this document consists of managers responsible for at least one of 
the following: 
 
 
 
 

the operation of an incident handling service 

the creation of an incident handling service 

the creation of a CSIRT 

the operation of a CSIRT 

As well as being a useful reference for higher management levels and all CSIRT staff, this 
document can also be of use to other individuals who interact with a CSIRT and would 
benefit from an awareness of the issues that affect a CSIRT, such as 
  members of the CSIRT constituency 
 
law enforcement 
  media relations 

CMU/SEI-2003-HB-002 

5 

We recognize that some organizations may choose to outsource their CSIRT services9 to 
other managed service providers, although we have not focused specifically on that audience 
in this handbook. We do believe, however, that the information contained in this handbook 
can be used by such providers and adapted to fit their approaches for providing fee-based 
services to an organization or enterprise. To that end, the handbook can be a valuable 
resource document for these service providers in identifying the same types of issues that 
other CSIRTs face in providing services to their constituency. 

1.3  Use of This Document 

This document is intended to provide a valuable resource to both newly forming teams and 
existing teams whose services, policies, and procedures are not clearly defined or 
documented. Ideally this document should be used at the early stages when an organization 
has obtained management support and funding to form a CSIRT, prior to the team becoming 
operational. However, the material can still be a very useful reference document for 
operational teams. 

This material can be used by a newly forming team as the basis for understanding the issues 
involved in establishing a CSIRT. The information can then be used to assist the development 
of detailed domain- or organization-specific service definitions, policies, procedures, and 
operational issues. As a result of applying the material provided in this document, an 
organization should be on a fast track to a documented, reliable, effective, and responsible 
incident handling service. 

In addition, an existing team can use this document to ensure they have covered the main 
issues and options that are appropriate for their organization when developing their incident 
handling service. 

Where applicable, the authors identify approaches that have proved successful, as well as 
pitfalls to avoid. In addition, various alternatives are described that might suit a particular 
situation or be applicable for a given type of team, such as an international response team, a 
national response team, an Internet service provider (ISP) team serving its customers, or a 
team for a single organizational entity such as a university or corporation. It is important, 
however, to note that this material is provided for reference and guidance. It is not intended to 
dictate the range or content of services, policies, and procedures that any given team should 
implement. These must be determined based on the individual needs of the CSIRT and the 
constituency it serves. Hence, we encourage you to use the material provided in this 

                                                 
9 

The Networked Systems Survivability Program at the Software Engineering Institute with funding 
support from the General Services Administration Federal Computer Incident Response Center 
(GSA FedCIRC) developed the report Outsourcing Managed Security Services. This document 
is available from the CERT Web site at http://www.cert.org/security-improvement/modules/omss/. 

6 

 

CMU/SEI-2003-HB-002 

document to understand the issues appropriate for your teams unique environment and to 
choose approaches that meet your teams particular goals, needs, and requirements. 

1.4  Document Structure 

The rest of this document is organized as follows. Chapter 2 presents the basic framework of 
the CSIRT model and describes basic issues that need to be considered and addressed by 
every CSIRT. It also introduces general CSIRT terminology and concepts including the 
importance of a clearly defined constituency, generation and implementation of policies, and 
the impact of organizational and legal issues on a CSIRT. It introduces a range of services 
that a CSIRT might provide and discusses how those services interact with the incident 
handling service. This sets the context for the main focus for this documentthe incident 
handling service, which is described in detail in Chapter 3. Chapter 3 describes the 
construction of an incident handling service and its functional components. Additionally, it 
discusses the range and nature of interactions that are associated with an incident handling 
service and how information (mostly of a sensitive nature) is handled. For completeness, 
Chapter 4, Team Operations, addresses practical operational and technical issues that every 
CSIRT must consider. These issues, such as equipment, security, and staffing considerations, 
are not all exclusive to an incident handling service, but they are critical to its success. The 
document concludes with some closing remarks followed by information about the authors, a 
bibliography of CSIRT-related materials, and a glossary of abbreviations and terms. 

CMU/SEI-2003-HB-002 

7 

 

8 

 

CMU/SEI-2003-HB-002 

2  Basic Issues 

A CSIRT may offer a range of services. However, it must at least provide an implementation 
of the incident handling service discussed later in this chapter and covered in depth in 
Chapter 3. Without providing at least a component of the incident handling service, the team 
cannot be called a CSIRT. Consider the analogy with a fire department. A fire department 
may provide a range of services (fire prevention, awareness, training), and it may undertake 
fire safety inspections. But at the core is the emergency response component. By providing 
the emergency fire department, it stays up-to-date and in touch with reality, and it gains 
community trust, respect, and credibility. Similarly, in an attempt to reduce the effect of 
incidents through early detection and reporting or to prevent incidents, a team can be 
proactive through awareness, training, and other services; but without the incident handling 
service, the team is not a CSIRT. 

This chapter presents the basic framework of the CSIRT model and describes the issues that 
affect every CSIRT. These issues need to be considered and addressed for all CSIRTs 
regardless of their size, nature, or scope. We begin by describing the CSIRT framework in 
terms of what it sets out to do (mission), for whom (constituency), what its roots look like 
(place in organization), and who its peers are (relationship to others). Next, we examine a 
framework derived directly from the mission statement: the service and quality framework, 
featuring CSIRT services, quality assurance, policies as major components, and information 
flow as an essential boundary condition. In the last section, we review the issues faced when 
adapting a CSIRT to the specific needs of its environment, where the legal issues are a 
particularly important component. 

2.1  CSIRT Framework 

In the search for a quick fix to establishing guidelines under which a new team will operate, 
many people go in search of existing CSIRT guidelines with the hope that they can simply be 
adopted for use in their environment. However, they soon realize that no single set of service 
definitions, policies, and procedures could be appropriate for any two CSIRTs. Moreover, 
teams with rigid guidelines in place find themselves struggling to adapt to the dynamic world 
of computer security incidents and attacks. 

It is important to understand the inherent structure and needs of the environment in which the 
CSIRT will operate, and the posture that the CSIRT will take in relation to risk management 

CMU/SEI-2003-HB-002 

9 

within that environment. With that understanding, the reader will be better positioned to 
apply this material to best suit that structure and set of requirements. Ultimately, of course, 
each team must define its own set of criteria and operating guidelines that supports its 
environment and constituency. 

To obtain that goal in a structured fashion, it is best to start with and to recognize a basic 
framework for a CSIRT. That framework consists of the questions what to do, for whom, 
in what local setting, and in cooperation with whom. We capture this set of questions for 
the framework as identifying the 
  mission statement: high-level goals, objectives, and priorities 
 
  place in organization: position within organizational structure and particularly within risk 

constituency: constituency type and relationship with the constituency 

management 

 

relationship to others: setting of (inter)national CSIRT cooperation and coordination and 
other interactions 

2.1.1  Mission Statement 

Many CSIRTs in existence today either lack a clear understanding of their goals and 
objectives or have failed to effectively communicate that information to the parties with 
whom they interact. As a result, they needlessly expend effort and resources (often in crisis 
situations) in an attempt to 
  understand if they are using the correct priorities to ensure they respond to the most 

important activity 

correct any inappropriate expectations of those they interact with 

 
  understand how and whether it is appropriate for them to react to a given situation 
 
  determine if the range and nature of the services they offer should be modified 

revise their policies and procedures to meet the needs of the situation 

Until a CSIRT defines, documents, adheres to, and widely distributes a concise and clear 
mission statement, the situation is not likely to improve. Given the importance of the 
statement, it should be non-ambiguous and consist of at most three or four sentences 
specifying the mission with which the CSIRT is charged. The statement will help provide a 
basic understanding of what the team is trying to achieve; and more importantly, it will 
provide a focus for the overall goals and objectives of the CSIRT.  

In addition, the mission statement of a CSIRT must have the backing and support of senior 
management in the parent organization (e.g., the corporate security officer, head of 

10 

 

CMU/SEI-2003-HB-002 

information technology, board of directors, or equivalent). Without such backing the CSIRT 
will struggle to obtain recognition and resources.  

A mission statement is imperative to enable the CSIRT to establish a service and quality 
framework, including the nature and range of services provided, the definition of its policies 
and procedures, and the quality of service. Together with the definition of the constituency, 
this service and quality framework (detailed in Section 2.2) drives and bounds all CSIRT 
activities. Clearly, if the team is housed within a larger organization or is funded from an 
external body, the CSIRT mission statement must complement the missions of those 
organizations. 

Many CSIRTs additionally supply a purpose statement that supplements the mission and 
explains the reason(s) that resulted in the team being established. Armed with this 
information, the CSIRT should be in a good position to define its goals and appropriate 
services to support its mission. The public availability of these statements will facilitate the 
understanding of the CSIRT (its role, purpose, and the framework within which it operates) 
by other parties who will inevitably interact with the CSIRT during the course of its 
operation. 

2.1.2  Constituency 

During the course of its operation, every CSIRT will interact with a wide range of entities. 
The most important of these is the specific community that the CSIRT was established to 
serve: its constituency. A CSIRT constituency can be unbounded (the CSIRT will provide 
service to anyone requesting it), or it can be bound by some constraints. Most commonly, 
CSIRTs have bounded constituencies that tend to be a reflection of the CSIRT funding 
source.10 The most common constraints that are used to bound a constituency include 
national, geographical, political (e.g., government departments), technical (e.g., use of a 
specific operating system), organizational (e.g., within a given corporation or company), 
network service provider (e.g., connection to a specific network), or contractual (e.g., the 
customers of a fee-for-service team). 

Table 1 provides examples for how different types of CSIRTs may fulfill differing missions 
and serve differing constituencies. 

                                                 
10   Kossakowski, Klaus-Peter. The Funding Process: A Challenging Task. 6th Workshop on 

Computer Security Incident Handling, Forum of Incident Response and Security Teams, Boston, 
Mass., July 1994. 

CMU/SEI-2003-HB-002 

11 

Table 1:  Examples of CSIRT Types With Associated Missions and Constituencies 
CSIRT Type 
International Coordination Center 

Type of Constituency Served 
Other CSIRTs around the world 

Nature of Mission 
Obtain a knowledge base with a 
global perspective of computer 
security threats through 
coordination with other CSIRTs. 
Building a web of trust among 
CSIRTs. 
Improve the security of the 
corporations information 
infrastructure and minimize threat 
of damage resulting from 
intrusions. 
Improve the security of a given IT 
product. 

System and network administrators 
and system users within the 
corporation 

Users of the product 

Corporation 

Technical 

An essential task for the CSIRT is to define its constituency and its relationship to that 
constituency, and then go on to promote the CSIRT to the constituents and gain trust by 
doing the job right. The next few sections focus on some of these issues as they relate to 
aspects of the constituency and relationships across those boundaries. 

2.1.2.1  Constituency Definition 

A constituency might be defined in the form of a statement and may be supported by a list of 
domain names. 

Example: The constituency of the Pennsylvania State University response team can be 
defined simply as Pennsylvania State University and as the domain *.psu.edu. 

On the other hand, it can be difficult (or even impossible) for a different type of team to 
define its constituency in terms of domain names because its constituency may be very large 
and dynamic (changing as customers come and go). 

Example: The constituency of AusCERT can be defined simply as Subscribers of the 
AusCERT service, but not everyone within the domain *.au will be a subscriber to 
AusCERT services. However, although AusCERT services are tailored towards their 
subscribing customers, in practice other external CSIRTs have used AusCERT as a point 
of contact for facilitating communication between Australian sites and other sites 
involved in computer security incidents. 

Even when a constituency seems to be easy to define in the form of a single domain, there 
can be complications. In an academic environment (such as a university), student or faculty 
clubs, commercial spin-offs, or systems owned by research organizations might coexist on 
the university network. Such systems may or may not use the university domain name and 
may or may not fall under the CSIRT for the university. 

12 

 

CMU/SEI-2003-HB-002 

Example: The CERT/CC is part of Carnegie Mellon University and is housed at the 
Software Engineering Institute; however, the CERT/CC manages its computing 
infrastructure separately from the university (and the Software Engineering Institute). 
Further, the CERT/CC is not the CSIRT for Carnegie Mellon University. 

Depending on the range of services offered by a CSIRT and the nature of those services, a 
CSIRT may have the need to define more than one constituency. These multiple 
constituencies might intersect, be sub- or supersets, or be totally separate from other 
constituencies served by that CSIRT. For instance, a technical CSIRT might provide general 
security information on its specialized products to an unbounded constituency (e.g., the 
Internet) via a publicly available Web site, but may provide an enhanced range of services to 
only a subset of that constituency, such as the registered users of its products. 

Even in the case of a CSIRT with a very bounded constituency, the CSIRT will most likely 
still have to deal with information associated with (or coming from) parties that do not 
belong to its constituency. For instance, a CSIRT providing an incident handling service to a 
bounded constituency will undoubtedly wish to accept incident reports that directly affect its 
constituency from parties outside of its constituency, appropriately handle that information, 
and ensure that it reaches the appropriate points of contact and is coordinated within its 
constituency. Many CSIRTs act as a coordination point between their constituency and other 
external parties (such as other CSIRTs, system administrators, vendors, law enforcement, 
legal counsel, and the media). These interactions can vary from simply relaying requests to 
complete sharing of data and full cooperation [Pethia 1990c]. It is important that a CSIRT 
decides, documents, and states how such interactions will be handled (see Section 3.7, 
Interactions, for more details on this topic). 

In some cases CSIRTs specifically choose not to advertise their constituency. For instance, a 
network service provider CSIRT may consider its customer list to be proprietary information 
and so will not disclose the information. Similarly, a CSIRT that provides fee-for-service may 
have contractual agreements with its customers that prevent the CSIRT from disclosing its 
constituency. In such cases CSIRTs revert to describing their constituency in very generic 
terms such as the customers of this organization. This makes it hard or impossible for such 
CSIRTs to provide incident response coordination services to their constituency, as other 
external sites and teams do not know if a given constituent falls within a CSIRTs 
constituency and so cannot report the activity directly to the appropriate team. What often 
occurs in these situations is that the customers are contacted directly by other sites or CSIRTs 
involved in an incident, and then as necessary the customers may (or may not) choose to seek 
support from their own CSIRT. It does point out how web-like trust relationships can evolve. 

2.1.2.2  Overlapping Constituencies 

Not all CSIRTs have unique constituencies. It is not uncommon for two or more CSIRTs to 
offer any given service to overlapping constituencies. However, experience has shown that 

CMU/SEI-2003-HB-002 

13 

such situations of overlapping constituency will result in confusion between the CSIRTs and 
their constituencies unless all parties involved have a clear understanding of their 
responsibilities. There have been cases when CSIRTs with overlapping constituencies have 
not coordinated with each other appropriately, resulting in duplication of effort and 
antagonism between all concerned. Similarly, there have been situations when the 
constituents have not known from which CSIRT to seek support or assistance and as a result 
made duplicate or inappropriate reports. 

Example: Consider a commercial company that has a contractual agreement with a fee-
for-service CSIRT, and as a result falls into the constituency of the fee-for-service CSIRT. 
Additionally, as the result of being located in a given country, the company falls into the 
constituency of that countrys national response team. 

Example: German federal government organizations are connected to the German 
DFN-network for provision of communication and Internet access [Kossakowski 1994]. 
Many of these organizations fall into the constituencies of two teams: 

  DFN-CERT, as a result of the organizations being connected to the DFN-network, 

and 

  CERT-BUND, a team set up by and inside the German Information Security Agency 
(BSI [Bundesamt fur Sicherheit in der Informationstechnik]) to address the specific 
needs of German federal government sites. 

If any incidents affecting German federal government sites are reported, both teams will 
coordinate their activities as appropriate. While CERT-BUND will provide incident response 
support towards federal government sites, DFN-CERT might provide technical support in 
terms of analysis of vulnerabilities together with CERT-BUND. Both teams will discuss and 
coordinate any response affecting both teams. 

Example: The CERT/CC has received (and on occasion, continues to receive) calls from 
individuals who are members of another CSIRTs constituency. In one case a system 
administrator at a university in the United Kingdom called the CERT/CC in the U.S. for 
assistance with an incident. The time in the United Kingdom was 9:00 a.m.; in the U.S. 
the local time was 3:00 a.m. A CERT/CC staff member was paged and provided 
immediate assistance to the site. The administrator in the U.K. (who was new to his job) 
was not aware of the services offered by JANET-CERT. Once he was informed of the 
existence of JANET-CERT and how it could offer him more appropriate service in terms 
of local needs and time zone, he contacted JANET-CERT directly. JANET-CERT 
followed up by providing the necessary support and advice, in fact being able to provide 
details related to the legal situation that the U.S.-based CERT/CC was not able to 
provide. 

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CMU/SEI-2003-HB-002 

2.1.2.3  Relationship to Constituency 

The nature of the relationship between a CSIRT and its constituency will directly affect the 
nature of the services that the CSIRT offers. As described in Table 2, those relationships fall 
into three general categories when considered in terms of the authority the CSIRT has over its 
constituents. 

Table 2:  Possible Authority Relationships Between a CSIRT and Its Constituency 
Level of Authority 
Full 

Shared 

None 

CSIRT/Constituency Relationship 
The members of the CSIRT have the authority to 
undertake any necessary actions or decisions on behalf 
of their constituency. 
The members of the CSIRT provide direct support to 
their constituents and share in the decision-making 
process (i.e., have influence in constituency decisions, 
but are unable to dictate to them). 
The members of the CSIRT have no authority over 
their constituency and can act only as advocates or 
advisors. 

A fourth authority relationship, indirect authority, is possible but not common. In such a 
relationship, the CSIRT can exert pressure on its constituency to enforce sanctions if needed. 
The influence that a major network service provider (NSP) CSIRT may have over an Internet 
service provider (ISP) that it provides service to, or the influence that the ISP may have over 
its customers, are good examples of indirect authority. 

Regardless of the authority relationship, some form of incident handling, or vulnerability 
analysis and response, or training services can be offered. However, services such as incident 
tracing and intrusion detection (listed in Table 4, List of CSIRT Services) may not be 
possible if the CSIRT has no authority over the constituency. In such cases some form of 
these services may be possible with contractual agreements in place to support them. But 
such agreements change the authority relationship to some extent. 

Example: Take the situation where a CERT Advisory is released that announces an 
available patch for a security vulnerability in a widely used network daemon, exploitation 
of which results in a system compromise. Consider how CSIRTs with differing authority 
over their constituencies may react to such an announcement: 

Full Authority 
The CSIRT could require all constituents to disconnect from the network until they have 
installed the patch. Moreover, the CSIRT may manually intervene to disconnect those 
constituents that do not comply. 

Shared Authority 
The CSIRT could advise and influence constituents to disconnect from the network until 

CMU/SEI-2003-HB-002 

15 

the patch has been installed. Additionally, it might assist the constituency by helping with 
coordination and response to the advice. 

No Authority 
The CSIRT can advise the constituency and propagate information to the constituency. In 
addition, the team can try to motivate the constituency to install the patch. However, the 
CSIRT cannot force the constituency to install the patch. 

2.1.2.4  Promoting the CSIRT to the Constituency 

Once the constituency has been defined, it will be important (regardless of the range and 
nature of the CSIRT services) to publicly advertise the constituency definition and the CSIRT 
services to ensure that both the constituency and other parties understand what interactions 
they might expect with the CSIRT. Particularly if a CSIRT intends to serve as a single point 
of contact for its constituency for computer security incident reports, it must ensure that it 
advertises its constituency to ensure that all concerned know to report incidents directly to the 
CSIRT rather than to an individual constituent. Similarly, constituents need to know which 
CSIRTs are offering them service and how to report to the appropriate CSIRT. 

A teams constituency can be viewed in several ways: 
  declared constituency: the constituency that the team claims or wishes to represent 
 

contractual constituency: the subset of the teams declared constituency who have a 
contractual agreement to report to the team (regardless of whether they make reports to 
the team or not) 

 

reporting constituency: the subset of the teams declared constituency that recognizes the 
team as representing it and as a result makes reports to it 

  others: parties who fall outside the declared constituency of the team and require its 
services or make reports to it anyway. These might include those who do not know if 
they have a team that they can report to. 

A CSIRTs goal should be to promote itself and its services as widely as possible to ensure 
that its declared constituency is aware of the team, ensure that other teams know of the 
CSIRT and the constituency it serves, and to gain broader recognition of the team in general. 
If the team does not effectively communicate its role and services it cannot expect to increase 
the size of its reporting constituency or its recognition within the broader CSIRT community.  

A CSIRT should promote itself through as many communication channels as possible, 
including the use of 
 
  CSIRT or organizational information/Web server 

constituency email lists and newsgroups 

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CMU/SEI-2003-HB-002 

  presentation, workshop, and tutorial materials 
  general awareness materials and newsletters (both regular and flash) 
 

the media (who can reach those portions of the constituency or management levels that 
do not tend to use email, Web, or other online communication methods) 

2.1.2.5  Gaining Constituency Trust 

Regardless of the CSIRTs (authority) relationship with its constituency, it must do more than 
simply define and publicize the constituency that it claims to serve. It cannot operate 
effectively without gaining and maintaining the constituencys trust and respect. Even if a 
CSIRT has total authority over its constituency, it does not mean that the constituencys trust 
and respect can be assumed in such a relationship. This trust must be earned and nurtured. As 
the team gains the trust and respect of its declared constituency, more of the declared 
constituency will begin to recognize and support the team, resulting in the growth of the 
teams reporting constituency. Experience indicates that it takes about a year from the time 
that a team commences operations and announces its declared constituency before a stable 
reporting constituency is established. 

Regardless of the constituency defined by a CSIRT, it is rare for any team to achieve 100% 
recognition by its constituency. It is useful to keep this in mind when trying to predict the 
impact that a team can have over its declared constituency. No matter how hard a team may 
try to reach out to its constituency and offer help or influence, it is unlikely that all of the 
constituency will respond. 

2.1.3  Place in Organization 

In the basic framework for a CSIRT, one needs not only to state what the team aims to do 
(mission statement) and for whom (constituency), but also to properly define the roots of 
the CSIRT: its place in its parent organization. This is not just a matter of administrative 
definitionwere it only that, this section would not be necessary.  

The place that a CSIRT holds in its parent organization is tightly coupled to its stated 
missionand to a lesser degree, its constituency. This is best demonstrated by considering 
the extreme example of a CSIRT with a very highly visible supportive mission for a Fortune 
500 constituency. If placed under the system administration department of its parent 
organization (a clear mismatch in responsibility), it is destined to fail. To help avoid such 
pitfalls, relevant aspects of a CSIRTs position within its parent organization are discussed in 
this section. 

CMU/SEI-2003-HB-002 

17 

A CSIRT may constitute the entire security team for an organization or may be totally distinct 
from an organizations security team.11 Alternatively, although an organization may not have 
a distinct CSIRT, this role may in fact be served implicitly by the organizations security 
team. Regardless of the implementation, provision of the incident handling service is the key 
issue. For the purposes of this document, we will consider a CSIRT in its most common and 
simplistic form, as part (from a small to total overlap) of a larger security team housed within 
a parent organization, as shown in Figure 1. 

 

Figure 1:  CSIRT Within an Organization 

In a corporate environment, a CSIRT must be well embedded within the organizations 
business structure and commonly resides within, or has some overlap, with the organizations 
IT security department. 

It is also possible for multiple incident handling capabilities to exist within a single parent 
organization. Such situations arise in vendor organizations and network service providers that 
may have two separate teams: one to handle incidents involving the companys own network, 
and another providing services to customers. Vendor organizations may also provide 
additional services such as those related to addressing security flaws in their products. 
Multiple capabilities might also arise in a single organization that does not provide services 

                                                 
11   A security team is defined as system, network, and security administrators usually located within 

an IT department whose job functions involve internal and external security defenses. For 
example, they handle security issues and technologies such as firewalls, anti-virus filters, secure 
remote access, and intrusion detection. The term security team can refer to individuals who 
perform these functions or to a group of individuals who work as a team. These individuals might 
be located in a centralized site, but more often are distributed across the enterprise. 

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CMU/SEI-2003-HB-002 

to external parties. For example, a company might choose to handle incidents related to or 
caused by malicious software through one team and use a different team for network attacks 
and intrusions. 

Before a CSIRT can begin to establish its operational guidelines, it is important to determine 
the role that the CSIRT plays in overall risk management in the context of its organizational 
environment and constituency. This role will vary depending on the nature of the parent 
organization and the nature of the constituency that the team serves. Whatever the resulting 
role, it is imperative that it is supported by management and understood by all parties 
involved. 

The parts of the organization that host the computing, networking, and communications 
equipment (on which data resides) clearly carry the technical risk. The business risk also 
needs to be considered, and that risk may be carried by many different parts of the 
organization. However, it is important to understand where the responsibility for managing 
risk resides, and how each part of the organization involved in this area interacts and 
coordinates their responsibilities. 

In a commercial organizational setting, different groups in the same organization may have 
the responsibility for different aspects of risk management. 

Examples: The network operations team responsible for network security issues; the 
system administrators responsible for host security issues; the physical security team 
responsible for access to buildings and facilities; the CSIRT responsible for coordination 
of response to any computer security incident reports; and corporate security responsible 
for setting company-wide policies and procedures including all other security-related 
teams and personnel. 

Regardless of their specific role in risk management, each group needs to understand how its 
responsibilities inter-relate to the other organizational components and how to coordinate 
with other groups to ensure that it does not operate in isolation (or contradict any other 
groups operations). This includes providing a clear description of each groups duties, 
interaction/escalation points, and shared responsibilities. 

Similarly, an organization may call upon the services of an external CSIRT. If so, the 
responsibilities and operations of the external CSIRT must be included and equally well 
defined in the organizations risk management framework. 

2.1.4  Relationship to Other Teams 

The realm of CSIRTs is the Internet, and therefore the world. There are many constituencies 
around the world, and a growing number are served by a CSIRT. In this regard, at some level 

CMU/SEI-2003-HB-002 

19 

these CSIRTs have to inter-operate in order to get their job done. This cooperation and 
coordination effort is at the very heart of the CSIRT framework: just stating the mission, 
defining constituency, and determining the CSIRTs place within organization are not 
sufficient without also covering the coordination issue. 

Within the context of CSIRTs as they exist today, there is some hierarchical structure that can 
be observed between the different types of teams. There are teams providing service to 
clearly marked constituencies and other teams who serve a coordination role across groups 
(commonly national or international) of CSIRTs. However, this structure is not a true 
hierarchy, and in most cases the structure is both informal and voluntary. This informal 
structure is seen as a benefit, as it allows teams the flexibility to share information quickly 
and effectively with other CSIRTs that they trust and to be more cautious with other teams 
with which there has not been as much opportunity to determine trustworthiness. 

Some formal hierarchies do exist, such as within the U.S. military. For example, the U.S. 
Army, Air Force, and Navy (ACERT/CC,12 AFCERT, and NAVCIRT, respectively), serve 
their own constituencies; while the U.S. Department of Defense DOD-CERT coordinates 
across all the U.S. military teams. 

Note that, for some types of activity, many teams choose to interact directly with other peer 
teams and not interact at all with a coordinating CSIRT. This commonly happens when the 
teams involved see no need to bring a coordinating CSIRT into the loop to address a specific 
problem. However, coordinating CSIRTs usually request that they be informed of all activity 
in order for them to obtain an overall view of the level of activity in their domain and alert 
other teams to look for additional or related activity. 

As depicted in Figure 2, there are various types of possible peer relationships between 
CSIRTs. A team may be considered as a coordinating CSIRT if it plays a coordination role 
among other CSIRTs. The example in Figure 2 depicts both CSIRTs A and B as coordinating 
CSIRTs. In addition to coordinating among CSIRTs C and D, CSIRT B has another 
constituency component that is not covered by C or D and is served directly by B. On the 
other hand, CSIRT A has a constituency that is solely made up of other CSIRTs (B, E, F, and 
G). However, the CSIRTs in As constituency do not fall into a rigid hierarchy because there 
is communication between CSIRTs E and F that can occur independent of their 
communications with CSIRT A. 

The relationships discussed in this section can be used to depict any CSIRT regardless of its 
setting or purpose. For instance, CSIRTs such as international coordination centers (e.g., 
CERT/CC), national response teams (e.g., DK-CERT, JPCERT/CC), fee-for-service response 

                                                 
12   The Army CERT, for example, plays a coordinating role itself across geographically dispersed 

regional Army teams (each called an RCERT). 

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CMU/SEI-2003-HB-002 

teams (e.g., dCERT, IBM/MSS), teams for commercial organizations (e.g., Motorolas 
MCERT, Boeings BCERT), network service provider teams (e.g., UNI-CERT, BT-
CERT/CC), and universities (e.g., Pennsylvania State Universitys PSU-CERT, Stanford 
Universitys SUNSeT) can all be represented using this approach. 

 

Figure 2:  CSIRT Peer Relationships 

2.2  Service and Quality Framework 

The mission statement of a CSIRT essentially has three derivativesservices, policies, and 
qualityeach of which needs to embody the scope and purpose of the mission statement. The 
services offered by a team are the methods used to carry out the teams mission. Services are 
usually provided to the teams constituency. Policies are the governing principles under 
which the team operates. Quality is the desired standard at which all activities will be 
undertaken. The information flowing within a CSIRT permeates all of the mission statement 
derivatives. Governed by services, policies, and quality, procedures specify how activities are 
enacted. This framework is depicted in Figure 3. 

Following this framework, the three derivatives of the mission statement (services, policies, 
and quality) will be discussed in more detail. Although information flow might naturally be a 
fourth topic to discuss, it will not be covered in this section. For the purposes of this 
handbook, we will mainly concentrate on the flow of information related to any external 

CMU/SEI-2003-HB-002 

21 

party. The internal flow of information (e.g., between team members, between different 
services provided) is nevertheless important for the team to define and improve. 

 

Figure 3:  Service and Quality Framework as Derived from Mission Statement 

We consider information flow of basic interest only where it pertains to external 
communication, and as a result, we view the flow of information (e.g., information flow 
inside the team) as clearly not a basic CSIRT issue. The topic of internal information flow 
will be discussed in relation to services in Section 2.4, Information Flow, and wherever 
relevant in the subsequent treatment of CSIRT issues in Chapters 3 and 4. 

A CSIRT can expect to offer a range of different services to its constituency that directly 
reflects the inherent promise of the CSIRT mission statement. The incident handling service, 
which is the focus of this document, will be described in detail in Chapter 3. To provide the 
necessary context for the discussion of the service, however, this section introduces issues 
that are generic to all CSIRT services and provides a brief discussion of other common 
services that a number of CSIRTs offer. 

For each service provided, the CSIRT should provide its constituency with service 
descriptions (or formal service level agreements) in as much detail as possible. In particular, 

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CMU/SEI-2003-HB-002 

any service provided by the CSIRT should include an explanation of the attributes and 
descriptions as outlined in Table 3. 

Table 3:  Service Description Attributes 
Attribute 
Objective 
Definition 
Function Descriptions 
Availability 
Quality Assurance 

Description 
Purpose and nature of the service. 
Description of scope and depth of service. 
Descriptions of individual functions within the service. 
The conditions under which the service is available: to whom, when, and how. 
Quality assurance parameters applicable for the service. Includes both setting and 
limiting of constituency expectations. 
The interactions between the CSIRT and parties affected by the service, such as 
the constituency, other teams, and the media. Includes setting information 
requirements for parties accessing the service, and defining the strategy with 
regard to the disclosure of information (both restricted and public). 
Define and specify the information flow exchange points between this service 
and other CSIRT services it interacts with. 
The relative priorities of functions within the service, and of the service versus 
other CSIRT services. 

Interactions and Information 
Disclosure 

Interfaces with 
Other Services 
Priority 

These descriptions are helpful to the team when defining, implementing, and operating the 
service. Similarly they provide information that should be made available (in some form) to 
the constituency to both advertise and set the appropriate expectations for the service. Since 
the nature of the field is one of constant change, reprioritization, and technical advancement, 
a CSIRT will need to frequently reassess the nature and levels of service it provides to keep 
pace with the changing environment and the resources available to it. Likewise, the 
constituency must be informed of any noticeable changes. 

2.3  CSIRT Services 

For a team to be considered a CSIRT, it must provide one or more of the incident handling 
services: incident analysis, incident response on site, incident response support, or incident 
response coordination. As we mentioned earlier in this handbook, the incident handling 
service includes incident analysis with at least one of the other incident handling services: 
incident response resolution, incident response support, or incident response coordination 
(see below for detailed explanations of the differences). In practice, we see that CSIRTs 
commonly offer other services in addition to the basic incident handling service13, depending 
on the needs of its constituency. These additional services might be provided by the CSIRT 
alone or in cooperation with other organizational units (such as the IT or security 
department). 

                                                 
13   Such other services might include, for example, distributing advisories, alerts and warnings, 
vulnerability handling, other proactive announcements, and/or training or awareness building 
within their constituency. 

CMU/SEI-2003-HB-002 

23 

In addition to the mandatory incident handling service, Table 4 lists some of the most 
common services that CSIRTs provide and the form that those services might take. Within 
this set of additional services, a few (such as announcements or vulnerability analysis and 
response) are even more likely to be offered, as they are closely associated with incident 
handling activities. 

Although this description focuses on services provided by CSIRTs, many of these same 
services can also be provided by system, network, and security administrators who perform 
ad hoc incident handling as part of their normal administrative work Sometimes such ad hoc 
teams are referred to as a security teams or other security-related groups. 

2.3.1  Service Categories 

There are many services that a CSIRT can choose to offer. The services that each CSIRT 
provides should be based on the mission, purpose, and constituency of the team.  

CSIRT services can be grouped into three categories: 
  Reactive services. These services are triggered by an event or request, such as a report of 

a compromised host, wide-spreading malicious code, software vulnerability, or 
something that was identified by an intrusion detection or logging system. Reactive 
services are the core component of CSIRT work. 

  Proactive services. These services provide assistance and information to help prepare, 
protect, and secure constituent systems in anticipation of attacks, problems, or events. 
Performance of these services will directly reduce the number of incidents in the future. 

  Security quality management services. These services augment existing and well-

established services that are independent of incident handling and traditionally performed 
by other areas of an organization such as the IT, audit, or training departments. If the 
CSIRT performs or assists with these services, the CSIRTs point of view and expertise 
can provide insight to help improve the overall security of the organization and identify 
risks, threats, and system weaknesses. These services are generally proactive but 
contribute indirectly to reducing the number of incidents. 

The services corresponding to each category are listed in Table 4 and described in detail 
below. 

It should be noted that some services have both a reactive and proactive side. For example, 
vulnerability handling can be done in response to the discovery of a software vulnerability 
that is being actively exploited. But it can also be done proactively by reviewing and testing 
code to determine where vulnerabilities exist, so the problems can be fixed before they are 
widely known or exploited. 

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Table 4:  List of Common CSIRT Services 

 

2.3.2  Service Descriptions 
2.3.2.1  Reactive Services 

Reactive services are designed to respond to requests for assistance, reports of incidents from 
the CSIRT constituency, and any threats or attacks against CSIRT systems. Some services 
may be initiated by third-party notification or by viewing monitoring or intrusion detection 
system (IDS) logs and alerts. 

Alerts and Warnings 

This service involves disseminating information that describes an intruder attack, security 
vulnerability, intrusion alert, computer virus, or hoax, and providing any short-term 
recommended course of action for dealing with the resulting problem. The alert, warning, or 
advisory is sent as a reaction to the current problem to notify constituents of the activity and 
to provide guidance for protecting their systems or recovering any systems that were affected. 
Information may be created by the CSIRT or may be redistributed from vendors, other 
CSIRTs or security experts, or other parts of the constituency. 

CMU/SEI-2003-HB-002 

25 

Incident Handling 

taking action to protect systems and networks affected or threatened by intruder activity 

Incident handling involves receiving, triaging,14 and responding to requests and reports, and 
analyzing incidents and events. Particular response activities can include 
 
  providing solutions and mitigation strategies from relevant advisories or alerts 
 
 
 
  patching or repairing systems 
  developing other response or workaround strategies 

looking for intruder activity on other parts of the network 

filtering network traffic 

rebuilding systems 

Since incident handling activities are implemented in various ways by different types of 
CSIRTs, this service is further categorized based on the type of activities performed and the 
type of assistance given as follows: 

Incident analysis. There are many levels of incident analysis and many sub-services. 
Essentially, incident analysis is an examination of all available information and supporting 
evidence or artifacts related to an incident or event. The purpose of the analysis is to identify 
the scope of the incident, the extent of damage caused by the incident, the nature of the 
incident, and available response strategies or workarounds. The CSIRT may use the results of 
vulnerability and artifact analysis (described below) to understand and provide the most 
complete and up-to-date analysis of what has happened on a specific system. The CSIRT 
correlates activity across incidents to determine any interrelations, trends, patterns, or 
intruder signatures. Two sub-services that may be done as part of incident analysis, 
depending on the mission, goals, and processes of the CSIRT, are 

  Forensic evidence collection: the collection, preservation, documentation, and analysis 
of evidence from a compromised computer system to determine changes to the system 
and to assist in the reconstruction of events leading to the compromise. This gathering of 
information and evidence must be done in a way that documents a provable chain of 
custody that is admissible in a court of law under the rules of evidence. Tasks involved in 
forensic evidence collection include (but are not limited to) making a bit-image copy of 
the affected systems hard drive; checking for changes to the system such as new 
programs, files, services, and users; looking at running processes and open ports; and 
checking for Trojan horse programs and toolkits. CSIRT staff performing this function 
may also have to be prepared to act as expert witnesses in court proceedings. 

                                                 
14   Triaging refers to the sorting, categorizing, and prioritizing of incoming incident reports or other 

CSIRT requests. It can be compared to triage in a hospital, where patients who need to be seen 
immediately are separated from those who can wait for assistance. 

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CMU/SEI-2003-HB-002 

  Tracking or tracing: the tracing of the origins of an intruder or identifying systems to 
which the intruder had access. This activity might involve tracking or tracing how the 
intruder entered the affected systems and related networks, which systems were used to 
gain access, where the attack originated, and what other systems and networks were used 
as part of the attack. It might also involve trying to determine the identity of the intruder. 
This work might be done alone but usually involves working with law enforcement 
personnel, Internet service providers, or other involved organizations. 

Incident response15 on site. The CSIRT provides direct, on-site assistance to help 
constituents recover from an incident. The CSIRT itself physically analyzes the affected 
systems and conducts the repair and recovery of the systems, instead of only providing 
incident response support by telephone or email (see below). This service involves all actions 
taken on a local level that are necessary if an incident is suspected or occurs. If the CSIRT is 
not located at the affected site, team members would travel to the site and perform the 
response. In other cases a local team may already be on site, providing incident response as 
part of its routine work. This is especially true if incident handling is provided as part of the 
normal job function of system, network, or security administrators in lieu of an established 
CSIRT. 

Incident response support. The CSIRT assists and guides the victim(s) of the attack in 
recovering from an incident via phone, email, fax, or documentation. This can involve 
technical assistance in the interpretation of data collected, providing contact information, or 
relaying guidance on mitigation and recovery strategies. It does not involve direct, on-site 
incident response actions as described above. The CSIRT instead provides guidance remotely 
so site personnel can perform the recovery themselves. 

Incident response coordination. The CSIRT coordinates the response effort among parties 
involved in the incident. This usually includes the victim of the attack, other sites involved in 
the attack, and any sites requiring assistance in the analysis of the attack. It may also include 
the parties that provide IT support to the victim, such as Internet service providers, other 
CSIRTs, and system and network administrators at the site. The coordination work may 
involve collecting contact information, notifying sites of their potential involvement (as 
victim or source of an attack), collecting statistics about the number of sites involved, and 
facilitating information exchange and analysis. Part of the coordination work may involve 
notification and collaboration with an organizations legal counsel, human resources or public 
relations departments. It would also include coordination with law enforcement. This service 
does not involve direct, on-site incident response. 

                                                 
15   Note that incident response is used here to describe one type of CSIRT service. When used in 

team names such as Incident Response Team, the term typically has the broader meaning of 
incident handling. 

CMU/SEI-2003-HB-002 

27 

Vulnerability Handling 

Vulnerability handling involves receiving information and reports about hardware and 
software vulnerabilities;16 analyzing the nature, mechanics, and effects of the vulnerabilities; 
and developing response strategies for detecting and repairing the vulnerabilities. Since 
vulnerability handling activities are implemented in various ways by different types of 
CSIRTs, this service is further categorized based on the type of activities performed and the 
type of assistance given as follows: 

Vulnerability analysis. The CSIRT performs technical analysis and examination of 
vulnerabilities in hardware or software. This includes the verification of suspected 
vulnerabilities and the technical examination of the hardware or software vulnerability to 
determine where it is located and how it can be exploited. The analysis may include 
reviewing source code, using a debugger to determine where the vulnerability occurs, or 
trying to reproduce the problem on a test system. 

Vulnerability response. This service involves determining the appropriate response to 
mitigate or repair a vulnerability. This may involve developing or researching patches, fixes, 
and workarounds. It also involves notifying others of the mitigation strategy, possibly by 
creating and distributing advisories or alerts.17 This service can include performing the 
response by installing patches, fixes, or workarounds. 

Vulnerability response coordination. The CSIRT notifies the various parts of the enterprise 
or constituency about the vulnerability and shares information about how to fix or mitigate 
the vulnerability. The CSIRT verifies that the vulnerability response strategy has been 
successfully implemented. This service can involve communicating with vendors, other 
CSIRTs, technical experts, constituent members, and the individuals or groups who initially 
discovered or reported the vulnerability. Activities include facilitating the analysis of a 
vulnerability or vulnerability report; coordinating the release schedules of corresponding 
documents, patches, or workarounds; and synthesizing technical analysis done by different 
parties. This service can also include maintaining a public or private archive or knowledge 
base of vulnerability information and corresponding response strategies. 

Artifact Handling 

An artifact is any file or object found on a system that might be involved in probing or 
attacking systems and networks or that is being used to defeat security measures. Artifacts 
can include but are not limited to computer viruses, Trojan horse programs, worms, exploit 
scripts, and toolkits.  

                                                 
16   A vulnerability is the existence of a flaw or weakness in hardware or software that can be 

exploited resulting in a violation of an implicit or explicit security policy. 

17   Other CSIRTs might further redistribute these original advisories or alerts as part of their services. 

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Artifact handling involves receiving information about and copies of artifacts that are used in 
intruder attacks, reconnaissance, and other unauthorized or disruptive activities. Once 
received, the artifact is reviewed. This includes analyzing the nature, mechanics, version, and 
use of the artifacts; and developing (or suggesting) response strategies for detecting, 
removing, and defending against these artifacts. Since artifact handling activities are 
implemented in various ways by different types of CSIRTs, this service is further categorized 
based on the type of activities performed and the type of assistance given as follows: 

Artifact analysis. The CSIRT performs a technical examination and analysis of any artifact 
found on a system. The analysis done might include identifying the file type and structure of 
the artifact, comparing a new artifact against existing artifacts or other versions of the same 
artifact to see similarities and differences, or reverse engineering or disassembling code to 
determine the purpose and function of the artifact. 

Artifact response. This service involves determining the appropriate actions to detect and 
remove artifacts from a system, as well as actions to prevent artifacts from being installed. 
This may involve creating signatures that can be added to antivirus software or IDS. 

Artifact response coordination. This service involves sharing and synthesizing analysis 
results and response strategies pertaining to an artifact with other researchers, CSIRTs, 
vendors, and other security experts. Activities include notifying others and synthesizing 
technical analysis from a variety of sources. Activities can also include maintaining a public 
or constituent archive of known artifacts and their impact and corresponding response 
strategies. 

2.3.2.2  Proactive Services 

Proactive services are designed to improve the infrastructure and security processes of the 
constituency before any incident or event occurs or is detected. The main goals are to avoid 
incidents and to reduce their impact and scope when they do occur. 

Announcements 

This includes, but is not limited to, intrusion alerts, vulnerability warnings, and security 
advisories. Such announcements inform constituents about new developments with medium- 
to long-term impact, such as newly found vulnerabilities or intruder tools. Announcements 
enable constituents to protect their systems and networks against newly found problems 
before they can be exploited. 

Technology Watch 

The CSIRT monitors and observes new technical developments, intruder activities, and 
related trends to help identify future threats. Topics reviewed can be expanded to include 

CMU/SEI-2003-HB-002 

29 

legal and legislative rulings, social or political threats, and emerging technologies. This 
service involves reading security mailing lists, security Web sites, and current news and 
journal articles in the fields of science, technology, politics, and government to extract 
information relevant to the security of the constituent systems and networks. This can include 
communicating with other parties that are authorities in these fields to ensure that the best 
and most accurate information or interpretation is obtained. The outcome of this service 
might be some type of announcement, guidelines, or recommendations focused at more 
medium- to long-term security issues. 

Security Audits or Assessments 

This service provides a detailed review and analysis of an organizations security 
infrastructure, based on the requirements defined by the organization or by other industry 
standards that apply.18 It can also involve a review of the organizational security practices. 
There are many different types of audits or assessments that can be provided, including 
 

infrastructure reviewmanually reviewing the hardware and software configurations, 
routers, firewalls, servers, and desktop devices to ensure that they match the 
organizational or industry best practice security policies and standard configurations 

  best practice reviewinterviewing employees and system and network administrators to 
determine if their security practices match the defined organizational security policy or 
some specific industry standards 

 

scanningusing vulnerability or virus scanners to determine which systems and 
networks are vulnerable 

  penetration testingtesting the security of a site by purposefully attacking its systems 

and networks 

Obtaining upper management approval is required before conducting such audits or 
assessments. Some of these approaches may be prohibited by organizational policy. 
Providing this service can include developing a common set of practices against which the 
tests or assessments are conducted, along with developing a required skill set or certification 
requirements for staff that perform the testing, assessments, audits, or reviews. This service 
could also be outsourced to a third party contractor or managed security service provider with 
the appropriate expertise in conducting audits and assessments. 

                                                 
18   Industry standards and methodologies might include Operationally Critical Threat, Asset, and 

Vulnerability EvaluationSM (OCTAVESM),  CCTA Risk Analysis and Management Method  
(CRAMM), Information Security Forums Fundamental Information Risk Management (FIRM), 
Commonly Accepted Security Practices and Regulations (CASPR), Control Objectives for 
Information and (Related) Technology (COBIT), Methode d' Evaluation de la Vulnerabilite 
Residuelle des Systemes d'Informa (MELISA), ISO 13335, ISO 17799, or ISO 15408. 

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Configuration and Maintenance of Security Tools, Applications, 
Infrastructures, and Services 

This service identifies or provides appropriate guidance on how to securely configure and 
maintain tools, applications, and the general computing infrastructure used by the CSIRT 
constituency or the CSIRT itself. Besides providing guidance, the CSIRT may perform 
configuration updates and maintenance of security tools and services, such as IDS, network 
scanning or monitoring systems, filters, wrappers, firewalls, virtual private networks (VPN), 
or authentication mechanisms. The CSIRT may even provide these services as part of their 
main function. The CSIRT may also configure and maintain servers, desktops, laptops, 
personal digital assistants (PDAs), and other wireless devices according to security 
guidelines. This service includes escalating to management any issues or problems with 
configurations or the use of tools and applications that the CSIRT believes might leave a 
system vulnerable to attack. 

Development of Security Tools 

This service includes the development of any new, constituent-specific tools that are required 
or desired by the constituency or by the CSIRT itself. This can include, for example, 
developing security patches for customized software used by the constituency or secured 
software distributions that can be used to rebuild compromised hosts. It can also include 
developing tools or scripts that extend the functionality of existing security tools, such as a 
new plug-in for a vulnerability or network scanner, scripts that facilitate the use of encryption 
technology, or automated patch distribution mechanisms.  

Intrusion Detection Services 

CSIRTs that perform this service review existing IDS logs, analyze and initiate a response for 
any events that meet their defined threshold, or forward any alerts according to a pre-defined 
service level agreement or escalation strategy. Intrusion detection and analysis of the 
associated security logs can be a daunting tasknot only in determining where to locate the 
sensors in the environment, but collecting and then analyzing the large amounts of data 
captured. In many cases, specialized tools or expertise is required to synthesize and interpret 
the information to identify false alarms, attacks, or network events and to implement 
strategies to eliminate or minimize such events. Some organizations choose to outsource this 
activity to others who have more expertise in performing these services, such as managed 
security service providers.  

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31 

Security-Related Information Dissemination 

archives of alerts, warnings, and other announcements 

reporting guidelines and contact information for the CSIRT 

This service provides constituents with a comprehensive and easy-to-find collection of useful 
information that aids in improving security [Kossakowski 2000]. Such information might 
include 
 
 
  documentation about current best practices 
  general computer security guidance 
  policies, procedures, and checklists 
  patch development and distribution information 
  vendor links 
 
  other information that can improve overall security practices 

current statistics and trends in incident reporting 

This information can be developed and published by the CSIRT or by another part of the 
organization (IT, human resources, or media relations), and can include information from 
external resources such as other CSIRTs, vendors, and security experts.  

2.3.2.3  Security Quality Management Services 

Services that fall into this category are not unique to incident handling or CSIRTs in 
particular. They are well-known, established services designed to improve the overall security 
of an organization. By leveraging the experiences gained in providing the reactive and 
proactive services described above, a CSIRT can bring unique perspectives to these quality 
management services that might not otherwise be available. These services are designed to 
incorporate feedback and lessons learned based on knowledge gained by responding to 
incidents, vulnerabilities, and attacks. Feeding such experiences into the established 
traditional services (described below) as part of a security quality management process can 
improve the long-term security efforts in an organization. 

Depending on organizational structures and responsibilities, a CSIRT may provide these 
services or participate as part of a larger organizational team effort. 

The following descriptions explain how CSIRT expertise can benefit each of these security 
quality management services. 

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Risk Analysis 

CSIRTs may be able to add value to risk analysis and assessments. This can improve the 
organizations ability to assess real threats, provide realistic qualitative and quantitative 
assessments of the risks to information assets, and evaluate protection and response 
strategies. CSIRTs performing this service would conduct or assist with information security 
risk analysis activities for new systems and business processes or evaluate threats and attacks 
against constituent assets and systems.  

Business Continuity and Disaster Recovery Planning 

Based on past occurrences and future predictions of emerging incident or security trends, 
more and more incidents have the potential to result in serious degradation of business 
operations. Therefore, planning efforts should consider CSIRT experience and 
recommendations in determining how best to respond to such incidents to ensure the 
continuity of business operations. CSIRTs performing this service are involved in business 
continuity and disaster recovery planning for events related to computer security threats and 
attacks. 

Security Consulting 

CSIRTs can be used to provide advice and guidance on the best security practices to 
implement for constituents business operations. A CSIRT providing this service is involved 
in preparing recommendations or identifying requirements for purchasing, installing, or 
securing new systems, network devices, software applications, or enterprise-wide business 
processes. This service includes providing guidance and assistance in developing 
organizational or constituency security policies. It can also involve providing testimony or 
advice to legislative or other government bodies. 

Awareness Building 

CSIRTs may be able to identify where constituents require more information and guidance to 
better conform to accepted security practices and organizational security policies. Increasing 
the general security awareness of the constituent population not only improves their 
understanding of security issues but also helps them perform their day-to-day operations in a 
more secure manner. This can reduce the occurrence of successful attacks and increase the 
probability that constituents will detect and report attacks, thereby decreasing recovery times 
and eliminating or minimizing losses.  

CSIRTs performing this service seek opportunities to increase security awareness through 
developing articles, posters, newsletters, Web sites, or other informational resources that 
explain security best practices and provide advice on precautions to take. Activities may also 
include scheduling meetings and seminars to keep constituents up to date with ongoing 
security procedures and potential threats to organizational systems. 

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33 

Education/Training 

This service involves providing information to constituents about computer security issues 
through seminars, workshops, courses, and tutorials. Topics might include incident reporting 
guidelines [CERT/CC 1998a], appropriate response methods, incident response tools, 
incident prevention methods, and other information necessary to protect, detect, report, and 
respond to computer security incidents. 

Product Evaluation or Certification 

For this service, the CSIRT may conduct product evaluations on tools, applications, or other 
services to ensure the security of the products and their conformance to acceptable CSIRT or 
organizational security practices. Tools and applications reviewed can be open source or 
commercial products. This service can be provided as an evaluation or through a certification 
program, depending on the standards that are applied by the organization or by the CSIRT. 

As a summary of the list of services described in the above section, our experience and 
discussions with others has shown that whatever services a CSIRT chooses to offer, the 
parent organization or management must ensure that the team has the necessary resources 
(people, technical expertise, equipment, and infrastructure) to provide a valued service to 
their constituents, or the CSIRT will not be successful and their constituents will not report 
incidents to them.19 

2.3.3  Selection of Services 

A CSIRT must take great care in choosing the services it will offer. The set of services 
provided will establish the resources, skill sets, and partnerships the team will need to 
function properly. The selection of services should first and foremost support and enable the 
business goals of the CSIRTs constituency or parent organization. The services provided 
should be those that the team can realistically and honestly provide based on the team size 
and range of expertise and skills.   

To a large extent, the success of the CSIRT will depend on the overall quality of the services 
it provides to its constituency. It is better to offer a few services well than a large range of 
services poorly. As a CSIRT gains the trust and respect of its constituency, it can look to 
expand its services as staff and funding permit. 

When deciding the range and nature of services to provide, care should be taken to ensure 
that the service selection supports and complements the overall CSIRT mission. In reality 
                                                 
19   If the CSIRT does not provide the services but outsources the activities to another organization 
such as a managed security services provider, the same standards for staffing, equipment, and 
infrastructure still are just as important and must be adhered to, in order to protect the CSIRT, 
organizational data, and services. 

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many teams offer a limited set of services but their constituencies insist on adaptations or 
additional services. If these additional demands are made from influential constituency 
members and the CSIRT is lacking high-level management support, the tendency is to 
provide some element of support for these services even if they fall outside of the teams 
official charter. 

Using the attributes and definitions in Table 3, any other additional services can be described 
in a similar fashion to the incident handling service presented in Chapter 3. 

2.4 

Information Flow 

Whatever services are offered by a CSIRT, it is important to understand which of those 
services are in some way related to each other and what the interdependencies are. In 
particular, it is necessary to specify the interfaces between the services and any associated 
information flow between the services. It is important to identify which services 
 
 
  have a shared need for a specific function or a specific set of information 
 

are responsible for providing/requesting the information to/from another service 

rely on information from, or provide information to, another service 

transfer information-dependent responsibilities (e.g., for confidentiality, appropriate use) 
to another service or externally (other CSIRTs, constituency) 

Using this information, it may be possible to optimize the use of resources, to avoid 
duplication of effort and make efficient use of pre-existing information. For example, all 
incoming requests could be handled by a centralized help desk that directs (or triages) the 
requests to the appropriate service. For other services handling incoming requests directly, 
care must be taken to ensure that any information flow linkages with other (related) CSIRT 
services are appropriately identified and shared to avoid unnecessary duplication of effort. 

Example: Consider a CSIRT that handles non-virus related incident reports and a separate 
department that handles any virus-related activity. Say a constituent contacts the CSIRT 
to report a compromise on a system that involves both modifications to the system (e.g., 
additional user accounts added, system changes, defaced Web-pages) and indications of 
virus-related activity (known viruses or worm programs installed on the compromised 
machine). At the same time, the constituent also notifies the CSIRT that there have been 
recent changes in personnel responsible for the affected system. The constituent provides 
the latest contact information for the new personnel. In this situation, the CSIRT has 
information that the virus-handling department should be aware of. After following their 
procedures for verifying information and requesting permission to pass the information 
on to the other department, the CSIRT passes the relevant information to the virus-
handling department. This eliminates the need for the constituent to separately contact 
the virus-handling department to notify them of activity. It also ensures that both groups 

CMU/SEI-2003-HB-002 

35 

are aware that there is activity that falls under each of their respective groupsthe two 
groups may collaborate or agree that one or the other will take the lead in bringing the 
incident to resolution.  

Care should be taken to ensure that information sharing is handled consistently and 
appropriately. Different services will have different information handling requirements. 
Depending on the specific situation, information flow may be restricted due to specific 
policies (such as an information disclosure policy). Moreover, these differing requirements 
may even prevent any sharing of information unless either some form of data cleansing can 
be enforced or appropriate contractual agreements are in place. This issue must be considered 
before deciding to share information between any given services and reviewed whenever 
policy and procedure changes occur. 

It may be necessary to give different priorities to similar types of requests depending on the 
source of the request. For example, the incident handling service could obtain simultaneous 
requests for incident statistics from both the vulnerability handling service (e.g., to assess the 
frequency with which a given vulnerability is exploited and prioritize further action) and the 
education/training service (in the process of updating public presentation materials). A higher 
priority would likely be given to the request from the vulnerability handling service, as it 
could have a more immediate effect on the overall incident statistics and how that affects the 
examination and analysis of a vulnerability (and perhaps the constituency, if the vulnerability 
handling service would be providing guidance to them). It would be a more reactive need 
than the proactive needs for updating training, education, and awareness components. This 
example also raises the issue of information sharing again. The information provided to the 
vulnerability handling service would most likely include details on the frequency of incidents 
reported that involve specific methods of exploitation. The information provided to the 
education/training service, on the other hand, would likely be sanitized of specific details 
about the information for any public training offering (at least in such a way as to remove 
details of yet unsolved exploitation methods, sites, etc.). 

Some basic examples of possible information-flow relationships between the most commonly 
provided CSIRT services and the incident handling service are outlined in  Table 5. These 
examples do not attempt to be comprehensive or specify mandatory interactions. They 
provide a flavor of the type of interactions to be expected. Of course, when considering your 
own set of CSIRT services it will be important to build a matrix of all possible service 
interactions, not just those with the incident handling service. 

Due to the limited resources available to many teams and the close associations between 
some of the common services, the distinction between different services may become blurred. 
When the distinction becomes artificial, it is probably wise to merge the closely related 
services into one service; the separate parts can then be labeled functions within the service 
according to the terminology of this handbook. 

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 Table 5:  Examples of Possible Information Flow to and from the Incident Handling 

Service 

Service Name 

Announcements 

Vulnerability Handling 

Artifact Handling 

Education / Training 

Intrusion Detection Services 
Security Audit or Assessments 

Security Consulting 

Risk Analysis 

Technology Watch 

Development of Security Tools 

Information flow 
to incident handling 
Warnings of current attack  
scenarios  

How to protect against exploitation 
of specific vulnerabilities 
Information on how to recognize 
use of specific artifacts 
Information on artifact  
impact/threat 
None20 

New incident report 
Notification of penetration test start 
and finish schedules 
Information about common pitfalls 
and the magnitude of threats 
Information about common pitfalls 
and the magnitude of threats 
Warn of possible future attack  
scenarios 
Alert to new tool distribution 
Availability of new tools for 
constituency use 

Information flow 
from incident handling 
Statistics or status report 
New attack profiles to consider  
or research 
Possible existence of new  
vulnerabilities 
Statistics on identification of  
artifacts in incidents 
New artifact sample 

Practical examples and motivation 
Knowledge 
New attack profile to check for 
Common attack scenarios 

Practical examples/experiences 

Statistics or scenarios or loss 

Statistics or status report 
New attack profiles to consider or 
research 
Need for products 
Provide view of current practices 

The following example highlights the relationship between services and the need to evaluate 
information flow between services. 

Example: Consider the scenario where a CSIRT offers (in addition to an incident 
handling service) a detailed security assessment service involving assigned team 
members that attack and test the specified systems. During the tests, administrators of the 
systems and networks involved are rarely made aware that the security assessment will 
take place. So, if during the test an insecure host is successfully attacked, the system 
administrator for this compromised machine may notice the activity, perceive it as a 
break-in, and report it as such to the CSIRT. If the security assessment service provides 
the incident handling service with advance notification of the test, the CSIRT team may 

                                                 
20   In the context of the flow and interaction outlined in  Table 5, we are not describing the training or 

mentoring that the incident handlers might need or obtain from other sources (although we 
recognize that it is needed and is an important component to the knowledge and skills within the 
team).  CSIRT education/training services are generally the recipients of output that originates 
from the other services (e.g., they gain the knowledge from the incident, vulnerability or artifact 
services, etc., provided by the incident handlers) and integrate information into the training 
products. These products are in turn packaged and provided to constituents in an appropriate form 
through training classes, seminars, meetings, or other types of venues. 

CMU/SEI-2003-HB-002 

37 

first verify with the security assessment team members if the activity reported is due to 
the testing. If not alerted in advance, the incident handling service might begin to expend 
unnecessary effort to respond to what they consider a legitimate incident report, such as 
alerting legal counsel or requesting support from other departments. As a result, precious 
resources of the CSIRT may be needlessly wasted. More importantly, the reputation of 
the CSIRT may be damaged in the eyes of those outside the team (such as the site 
management, system administrator, or legal counsel) because it rightly appears that 
within the CSIRT, one part of the team does not know what another part of the team is 
doing. 

2.5  Policies 

Policies are governing principles adopted by organizations or teams. This section will discuss 
in general terms what policies are and should be, and what properties they should have. But 
documented policies are not the end of the story. It is important to understand whether they 
are implementable, enforceable, and function as expected. This section concludes with a 
discussion of these issues. For more in-depth coverage of global policies (such as information 
disclosure policy and media policy) that are fundamental requirements for any CSIRT, refer 
to Section 4.2, Fundamental Policies. 

The policies of an organization need to be clearly stated and understood by all members of 
the organization. Without a clear understanding of policy, it will not be possible for the staff 
to correctly implement and enact their responsibilities. 

Where services are essentially defined for the customer (e.g., incident response support 
service or education/training service), the underlying policies for delivering the service are 
mainly internal guidelines for the team that dictate appropriate behaviors for some specific 
activity. Example policies in this case could include information categorization, security, 
media, and code of conduct. The latter two examples may prompt the objection that these are 
hardly only internal and that they have a lot to do with external communications. True 
enough, but this external aspect is not something offered to the customer; it is not a service in 
itself, it merely affects the manner and quality in which the service is delivered. 

A policy may be service-specific: an incident response support service, for example, may 
require a specific policy on caller authentication (defined in a procedure for verification of a 
caller before incident information can be discussed). Caller authentication may not be 
necessary within another service such as education/training or technology watch. In this 
section, the emphasis is on the overall policies encompassing the services of a CSIRT. 
However, most of what will be said here will also apply directly to any service-specific 
policies. 

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It is important to understand the relationship between policies and procedures, since these are 
often mingled and mixed. Procedures detail how a team enacts activities within the 
boundaries of its policies. Procedures can be very beneficial to help make a policy successful, 
but only on rare occasions can policies exist without corresponding procedures. An extremely 
simple media policy is Be very polite to the media and never lie, but only mention generic 
anonymous information. However, corresponding procedures help many staff members stay 
within the policy guidelines, especially in situations of stress. In the following discussion of 
policies, we will only make reference to procedures where this will add to an understanding 
of the case. 

2.5.1  Attributes 

Though it may seem trivial, it is essential to stress that a policy should not be defined as a set 
of detailed procedures. A policy should outline essential characteristics for a specific topic 
area (consider the above media policy example again) in such a way that all the necessary 
information is provided on which detailed procedures can be based to help implement the 
policy. All policies must be written with comparable levels of abstraction and should undergo 
legal and appropriate compliance review. Table 6 describes a set of attributes that every 
policy should have. 

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39 

Table 6:  Basic Policy Attributes 
Attribute 
Endorsed by 
Management 
Clear 

Description 
Like the mission statement, a policy cannot be enforced unless it is endorsed by senior 
management. 
Any team member, whether technical, management, or administrative, should be able to 
easily understand what a given policy is about. Avoid unnecessary jargon, dont be 
ambiguous, and use very short sentences. If possible (according to your disclosure 
restrictions), ask someone who is not in security or IT to read your policies. If he or she 
cannot understand them, rewrite the policies! 
A good policy is a short policy. A long policy is either a bad policy (or uses too many words) 
or one that may actually include a lot of procedures. 
Unfortunately, security policies in practice often tend to not be concise, confusingly mixing 
the management aspect (the policy) with the operational aspect (the procedures), resulting in a 
mixture that nobody really cares for. Strive to avoid this condition! 
A policy should include all that is needed to dictate appropriate behavior in some topic area 
(e.g., security policy), but no more than thatno redundancy, no resiliency. That can be built 
into the corresponding procedures and quality control. 
Avoid statements that sound nice but are of no use because they are open to interpretation, 
such as state-of-the-art security will be provided. Common sense statements like treat your 
customers with respect could be appropriate inside a policy: they are usable, because people 
share a common understanding about them. 
A policy must also be implementable. In the treat your customers with respect example, this 
may mean the addition of a statement essentially saying that regular training must be provided 
to help the staff understand how to deal with customers. 
Policies must be enforceable; otherwise they are of little or no value. Usually when a policy is 
implementable, it is normally also enforceable unless it contradicts itself. Concrete measures 
are needed to assess the usage of the policy. 
Example: An example of a contradictory policy is the security policy that ranks internal 
information security as priority number 1 but at the same time ensures absolute privacy for its 
staff; the latter makes it hard or even impossible to enforce security in case of an insider 
threat. 

Concise 

Necessary and 
Sufficient 

Usable 

Implementable 

Enforceable 

2.5.2  Content 

The content of a policy is mainly a definition of behavior in a certain topic area. Examples 
include how to behave toward the media, classify incoming information, and deal with the 
results of human errors. These features are boundary conditions for any policy definition. It is 
also possible to distinguish some generic features that should appear within the content of 
policies. These features are listed in Table 7 and, where appropriate, include examples (for 
consistency these examples will focus on the media policy arena). 

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Table 7:  Policy Content Features 
Feature 
Mission Link 
Identification of Roles 

Description 
Describe how the policy is derived from the mission statement. 
The parties/people involved in (aspects of) the policy should be clearly identified. 
Example: media, media liaison, and other staff. 
Duties and responsibilities of the identified parties should be defined, when appropriate. 
(Note: you cannot, however, define the duties of the media.) 
Describe the appropriate interaction between the parties identified within the policy. For 
example, only talk to the media in person or via telephone, insist on a list of questions 
to be asked in advance of the interview, insist on reviewing written text before 
publishing. 
Essential procedures can be called for, but should not be explained in detail within the 
policy. For instance, state that a procedure must be in place to verify the identity of a 
member of the media, or that only authorized staff may talk to media (and only after 
appropriate training). 
Identify the relationships between this policy, services and other policies. In the media 
policy example, a relationship with the security policy is obvious, as well as a 
relationship with the information intake process of an incident handling service. 
Describe responsibilities and guidelines for document maintenance and update (e.g., the 
request may be received through the triage function). 
It is essential to ensure that the CSIRTs definitions of terms are provided; all local 
organization terms and all acronyms are defined. This will ensure that everyone 
understands the policy, especially new team members. 

Responsibility 

Interaction 

Procedures 

Relationships 

Maintenance 

Glossary of Terms 

2.5.3  Validation 

After a policy has been defined it is advisable to check its validity in practice before actually 
implementing (and possibly enforcing) it. Checking validity means finding out if all the ideas 
in the policy can actually be translated into real-life behavior. 

Example: Only stating always be nice is not much help when one is confronted with 
persistently aggressive people. 

The following issues should be taken into account with regard to policy validation: 
 

If possible, ensure that the people responsible for the policy validation are not the same 
people who created the policy. This will help prevent any conflicts of interest and ensure 
an objective evaluation of the policy. 

  Pay particular attention to validating the policy attributes and content features detailed in 

Tables 6 and 7 to ensure that policies are not ambiguous. 

CMU/SEI-2003-HB-002 

41 

  Undertake consistency checking of the policy in relation to other policies, services, and 

procedures; and also within the policy itself. 
Example: Espousing network security yet using the practice of transmitting passwords in 
clear text. 

  Validate implementability and enforceability. Implementing the policy as a pilot and 

choosing some worst-case scenarios to check on real-life behavior, including 
enforceability, is a very good way to accomplish this validation of the policy. 

2.5.4 

Implementation, Maintenance, and Enforcement 

Once validation of the policy is completed, feedback should be given to the policy makers so 
they can make any revisions. Once the revisions are made the policy should be re-tested. 
Once the validation is complete and no more changes need to be made, the policy can be 
implemented. 

Once that is done, the policy will need to be maintained, i.e., it will be necessary to make 
regular checks on its behavior in real life. Many of these checks will be equivalent to the 
validation checks, and some new ones will be added. An example of the latter could be using 
the media policy to check if the media is indeed informed within a preset number of hours 
following their request for information. Clearly this real-life behavior could not have been 
measured previously during a validation phase. 

The checks originating from the validation process and the continued validation of the 
policies are really checks on the behavior of quality parameters. Both maintenance and 
enforcement (what to do if the checks say somethings wrong!) are part of the regular 
quality assurance system, discussed in Section 2.6, Quality Assurance. Every policy must 
have a regular maintainer who keeps track of the quality of service effected through use of 
the policy and proposes changes to the policy as appropriate. Things change over time, and 
no policy should be implemented once and used as is forever. The excuse Thats the way 
it has always been done is not acceptable in light of the changing nature of the technologies 
in use today, and the role(s) of the CSIRT and the services it provides to its constituency. 

2.6  Quality Assurance 

Just defining services, the flow of information between them, and procedures to make things 
work is clearly not enough to serve a constituency well. An associated form of quality 
assurance is also required. This assurance can range from a statement of the form we will 
try, to fully specified sets of quality parameters backed up by associated enforcement and 
escalation procedures, along with and liability and penalty clauses. 

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In the CSIRT arena, standard approaches are rarely used across all teams, although there may 
be similarities. A few teams attempt to at least prioritize incidents and work on what they 
regard as high-priority incidents first. One team reported that their most commonly used 
measure of quality was the absence of complaints reaching senior management. However, 
these were exceptions, as only very few teams undertake quality assurance (QA) either 
formally or informally. Lack of QA results in inconsistencies in the service provided, services 
that do not fulfill their purpose, and inappropriate use of staff resources. In this section we 
suggest a QA approach suitable for the CSIRT environment. Time and experience will tell 
what other approaches are (more) suitable for this domain. 

We will describe the basic quality assurance components and their use in the CSIRT 
environment. Our QA system consists of three parts: definition of a quality system, checks, 
and balances. 

In the definition, parameters are given that together describe the systems quality. The checks 
are there to actually measure these quality parameters. Finally, the balances ensure that the 
results of these measurements are used to assure quality. 

2.6.1  Definition of a Quality System 

The first step is to look for the smallest set of quality parameters sufficient for describing the 
QA level required by the mission statement. When more than one service is offered, several 
sets of quality parameters may be appropriate, one for each service. And, at an even more 
granular level, there can be subsets of parameters for functions within services. 

A quality system should be defined using a top-down approach, starting with the mission 
statement and going down to policies and services, functions that comprise those services, 
and all associated interactions and procedures. The mission statement should be such that one 
can derive a general sense of the CSIRTs perceived quality. The mission statement could 
involve quality perceptions like timely, best effort, or flexible. Clearly, all subsequent 
quality definitions should be in line with the mission statement. 

The set of quality parameters includes those for all policies, services, service functions, and 
procedures. Each of these elements will have its own subset of unique quality parameters, but 
some parameters may be common between services or service functions. It is important to 
bear in mind, however, that quality is dynamic, definable not only within policies, services, 
and service functions, but also between them, like information flow. Therefore one also needs 
to take into account the interactions of services when defining quality parameters. 

Example: Suppose the mission statement of a team mentions both incident and 
vulnerability handling services. Obviously it is then practical to define two different sets 
of quality parameters, one for the incident handling service, the other for the vulnerability 

CMU/SEI-2003-HB-002 

43 

handling service. A typical parameter for the incident handling set would be the 
maximum time that it takes to react to a constituents initial incident report. A parameter 
for the vulnerability handling set could be that one only gives out advice about a 
vulnerability if a solution is present. 

Extending the quality parameters, one can then consider the interaction between the 
incident and the vulnerability handling services also yielding good examples of quality 
parameters. For example, such a parameter could be the maximum time that a 
vulnerability service should take to provide an assessment of a vulnerability to the 
incident handling staff (or others) when the incident handling service discovers possible 
evidence of a vulnerability exploitation while analyzing an incident. 

To further clarify the diversity and breadth of quality systems, more examples of quality 
parameters are given below: 
 

response time for service events (e.g., incident, vulnerability report) and/or priority 
scheme 

level of information provided on longer term (reporting, summaries, announcements) 

level of information provided for service events (short term) 

time-to-live for service events 

 
 
 
 
  verification 

secrecy 

Having identified a suitable set of quality parameters, the quality system definition is 
completed by assigning values to all quantities among the parameters. 

Examples: 

Parameter 

Follow-up time on vulnerability reports 

Follow up on high-priority incidents 

Value 

For all non-urgent vulnerabilities, the 
CSIRT will follow-up with a constituent 
within two working days of the initial 
report. 

Every high-priority incident will be 
acknowledged within two hours. Analysis 
will start within the first hour of receipt of 
such a report. 

Follow up on low-priority incident reports  Every incident report will be 

acknowledged within 4 hours. Analysis 
will start within the first 48 hours after 
receipt of such a report. 

 

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It is important to realize that the quality system is not necessarily a static one, i.e., with all 
parameters simply defined and assigned specific values. It may well be the case that the state 
of one parameter dictates the values assigned to other parameters, or that one set of flexible 
parameters is used. 

Example: Consider a crisis situation, when everything looks different from normal. This 
can be handled with two different approaches: 

a.  Suppose a parameter crisis exists with possible values YES and NO, and 
several other quality parameters are also defined. If crisis equals NO, all of 
these parameters are in use and have values assigned. If, however, crisis changes 
to YES, a number of the quality parameters are ignored and the remaining ones 
(like response times) could be assigned more stringent values. 

b.  The CSIRT simply uses flexible parameters, such as 95% of all low-priority 

incidents are handled within five days. These are communicated to the 
constituency, who need not be explicitly aware when the CSIRT is in crisis mode. 

In both cases the CSIRT should take into consideration that constituents might feel left in the 
dark if they are not informed about changes in quality parameters for the service levels. 

2.6.2  Checks: Measurement of Quality Parameters 

It is not sufficient to just define a quality systemit must be checked to validate whether or 
not it lives up to your expectations. Checking quality parameters (measuring real-life 
behavior) is thus an essential part of any QA system. 

Having defined quality parameters, one also needs to define how to check these parameters 
and how to measure them. This is by no means a trivial task and dictates some serious  
a priori measures, like establishing a reporting system. Also you need to audit your check 
system regularly to see if it functions appropriately in real life and if it meets the ultimate 
demand: to be a good check on quality. 

This demand (for a check) explains why quality parameters should be clear-cut and 
preferably quantifiable: it is hard to measure qualifications like good or bad, whereas its 
easy to measure parameters such as the average time taken to act upon an initial incident 
report. 

It is useful to note that the frequency used to check on your parameters is really also a quality 
parameter in itself. Its value must be carefully optimized as well: too few checks clearly 
endanger QA, whereas checking too often will result in more time being used to live up to 
expectations, reprioritize etc., instead of actually getting the work done. 

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45 

2.6.2.1  Reporting and Auditing 

To track quality, it is necessary to have a workflow management system (for details of 
workflow management systems, see Section 4.3.2, Workflow Management) to measure 
parameters (such as response times, problem categories, and priorities) and a reporting 
system (to measure the use of standard and escalation procedures). Many different levels of 
reporting exist; a few obvious categories are reporting to operational management, overall 
management, the constituency, the world. When workflow management software is in place 
there is a tendency (or desire) to make reports automatically available. Care should be taken 
that such reports are not generated just because they can be done; they should be generated to 
provide information that is useful to and needed by the recipient. 

Regular auditing (or tracking) of the QA check system itself is also necessary to ensure the 
quality. The system must be checked for both sloppiness and inadequacy. It is necessary to 
  minimize the number of procedures necessary and make them crystal clear 
 

ensure that the CSIRT staff members understand why the procedures are in place (to 
enhance the motivation of the staff members) 

 

avoid the tiny details: it helps staff motivation if they are allowed to think for themselves 
(and it is nearly impossible to make rules for everything) 

  do audits and feed the results into the review cycles 

One common mistake is to develop long, complicated rules for evaluating the system, which 
often results in the need to do very rigid audits to ensure that the rules have been followed. 
Often these audits become so rigid that they have to be announced in advance, the result 
being that meeting the audit demands becomes a goal in itself instead of the audit serving the 
bigger goal of helping to assure quality. 

A quality check system can become inadequate even if it was originally designed to be very 
effective. This happens because quality parameters can change. 

Example: You define the initial response time for incident reports from customers as a 
parameter. This may be perfectly acceptable until you introduce an automated email 
response service that just acknowledges reports in a short message that says: We have 
received your report ... Thank you. While the process might be very fast indeed, it 
probably is not the quality parameter you set out to initially measure. Therefore you 
would need to refine your parameters to state, for example: An initial, automatic 
response will be sent out by email whenever the customer report is received. A personal 
response by one of our CSIRT staff will be sent out by email within 24 hours of the initial 
review.21 

                                                 
21   Or some other timeframe (or parameter) you define. 

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2.6.3  Balances: Procedures to Assure Quality 

Doing quality assurance checks on the real-life behavior of quality parameters is not enough. 
Procedures must be in place to enforce quality when it is at risk. Then, escalation procedures 
can be defined in the event that standard enforcement procedures fail, or if the quality system 
itself proves inadequate. Finally, penalty and liability clauses can help enforce quality and at 
the same time prevent the service provider from becoming excessively vulnerable to potential 
lawsuits. These procedures and clauses can best be characterized as the balances for quality 
assurance. 

In the demanding environment of a CSIRT, where staff stress levels are high and resources 
are generally fragile and stretched, it is important to ensure that staff members are able to 
accomplish their work to a high standard of quality without overwhelming them with 
unnecessary hurdles. As such, there is a need to seek the right balance between procedures, 
checking, and the ability to get the job done. Correctly written procedures will ensure a buffer 
for human errors; any procedure not taking (human) error into account is flawed by design 
(see Section 4.2.6, Human Error Policy). 

Also it is advisable to give customers (the constituents) some method to enforce quality, 
though this will normally be an indirect process. Not only does this sell well, but the best 
quality judgment often comes from those who actually use (or suffer) the service. One 
convenient way of granting constituents influence is by implementing measures such as user 
groups and/or advisory boards. Admirable though these measures are, the most effective way 
is probably by implementing penalty clauses: meaning the team has to pay or refund the 
customer money if it performs below the expected level of service.  

Note that it can also be the customer who fails to live up to his part of the deal. If that 
continues to be the case and is grave enough (e.g., as grave as non-confidentiality), then 
procedures should also be in place to discontinue or reduce support for such customers.  

From the CSIRT staffs perspective, escalation procedures are usually defined and an integral 
part of the overall CSIRT processes. However, operational management should be able to 
swiftly and effectively notify the higher levels of management when quality is truly at risk; 
waiting for the monthly or quarterly report to have its impact is not sufficient. The routine 
should include a decision on whether or not to notify customers of the problem and the 
estimated time to fix it. The decision will depend on the agreed service levels and the direct 
disturbance caused by the problem. Escalation can also take place when the quality system 
itself fails and needs to be fixed. 

Defining and advertising quality (but not assuring it) will cause the CSIRT to be liable in 
most countries if service parameters are not met and a constituent claims damage as a result 
of this failure. However, even in normal cases where a QA system is in place, including 

CMU/SEI-2003-HB-002 

47 

checks and balances, in some countries (notably the U.S.) liability claims are still to be 
expected. In some cases, adding liability clauses to QA will be useful, especially when 
penalty clauses are also in place. Such clauses are best handled by legal experts; simply 
denying responsibility for financial damage is not enough in most countries. 

The key point: If you define quality, make sure you assure it. Prioritize your assurance tools: 
education and awareness building are more effective tools than increasing pressure, 
especially in the long run. If a workflow management software system is in place, it is 
possible and advisable to integrate the regular enforcement and escalation procedures into 
this system. This saves work over time and also creates the possibility of producing reports 
on the use of these procedures. 

Last but not least: Procedures and policies are not made for eternity, and thus must have 
owners and/or maintainers, and a well-defined life cycle. All too often procedures are created 
in the project phaseand once the project is over, the change control vanishes, but the 
procedures are there to stay, out of control, until somebody really stumbles over them. 

2.6.4  Constituents View of Quality 

The set(s) of quality parameters for internal use must be complete to ensure that an 
appropriate quality level is maintained with respect to the mission statement. However, the 
set of quality parameters communicated to the constituency is generally some subset of those 
used internally. 

From a commercial point of view, it is advisable to communicate a mature (if not the full) set 
of parameters to the constituency. The message is that the constituency is taken seriously and 
that you have nothing to hide. On the other hand, from the same commercial point of view 
and sometimes from a liability point of view as well, it may be wise only to communicate 
those parameters that are easy for your CSIRT to assure. 

A compromise between both extremes is the best option. In any case, avoid communicating 
quality parameters whose definition is not crystal clear or establishing parameters that are 
impossible to quantify, however useful these may be to help assure overall quality. 
Constituents tend to dislike what they cannot grasp. 

2.7  Adapting to Specific Needs 

In many instances the reason for forming a CSIRT results from a specific need or problem 
experienced by the organization. Logically, whatever general structure is chosen for the 
CSIRT, it will be adapted to at least suit the specific need.  

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Example: A heterogeneous user community that experiences a lot of network-based 
attacks will establish a coordinating CSIRT facilitating support and coordination within 
this community. This team will not necessarily concentrate on computer viruses. 

Example: The coordinating CSIRT from the example above notices over time, from 
reports by the users as well as from other peer teams internationally, that computer 
viruses and worms are becoming a growing concern. The CSIRT identifies and obtains 
resources to invest in new staff members who specialize in malicious software attacks. 

Example: An organization with significant computer virus problems that already has a 
well-established antivirus team builds a CSIRT that does not respond to computer viruses 
or other malicious software incidents, but concentrates on network attacks. Agreed 
interactions and interfaces between the CSIRT and the anti-virus team assures that 
cooperation takes place whenever useful and necessary. 

Every team has its own circumstances to adapt to. The result is that no two CSIRTs are alike 
in details, only in basic structure. 

Example: CSIRTs with full authority (including access to a constituents systems) but 
working in an environment with highly sensitive data (military, commercial, health care) 
must adapt to the extra stringent security measures and extensively screen their 
personnel. The levels of screening may be different across these CSIRTs, and the services 
provided may be similar or very different. 

Clearly each CSIRT will begin developing and adapting their requirements when defining the 
mission statement and services. Naturally these changes must also be reflected in the quality 
assurance system as appropriate. But where adaptation will be most evident is in a CSIRTs 
policies and proceduresand in the rather practical treatment of team operations (described 
in Chapter 4).  

Fundamental policies will implicitly surface, however, as illustrated in these next examples. 

Example: A military or company CSIRT will have a rather restrained media policy 
covering all issues and topics. 

Example: A coordinating CSIRT serving a national research network user community 
will have a media policy that allows them to describe all technical details but does not 
allow the CSIRT to reveal the identities of people or organizations involved. 

Example: An anti-virus CSIRT will have stringent procedures for how to deal with 
incoming binaries (such as virus samples), including an isolated test environment and 
complete backup images to reinstall the test environment back to its initial clean state. 

CMU/SEI-2003-HB-002 

49 

Example: A coordinating CSIRT without any analysis services has stringent procedures 
as well, but when they receive a virus sample (binary) they will simply isolate the artifact 
after a mandatory computer virus check. As they have no analysis capabilities in-house, 
they may not do any further analysis of the binary received. 

Two topics remain that deserve attention at this level. The first is the general ability of the 
CSIRT to readily adapt to changing circumstances that every CSIRT must face in order to do 
a proper job. The second topic is that of law, liability, and regulation. These will be discussed 
below. 

2.7.1  The Need for Flexibility 

CSIRTs need to be prepared for the dynamic environment of computer security incidents and 
attacks. A CSIRT needs to be ready to address any situation that may not be explicitly 
covered by its existing guidelines or expertise. Some of the factors that make the CSIRT 
environment so dynamic, coupled with their impact on CSIRTs, are provided in Table 8 as an 
illustration for the need to be flexible. 

Table 8:  Examples of Dynamic Environment Factors and Their Impact on CSIRTs 
Factor 
The rate of incident reports a CSIRT receives cannot be 
easily predicted. 

CSIRT Impact 
A CSIRT will experience unexpected and 
extended peaks in workload or conflicting 
priorities. 
The type and complexity of incidents reported to a 
CSIRT will change over time. 

Intruders (or attackers) are constantly devising and 
implementing new methods of exploitation by devising new 
attack methods or modifying existing attack methods to 
open new exploitation possibilities. 
Advances in technology bring new possibilities for 
exploitation, such as those resulting from Java and ActiveX. 

In some countries laws are just being developed to address 
what they see as a new problem. Computer crime laws are 
under review and undergoing active revision in many 
countries around the world, in an attempt to keep pace with 
the changing technology and threats posed by intruder 
activity. 
Varying demands will be made on the CSIRT based on the 
needs, technical expertise, experience, and level of 
understanding of each of the parties with whom it interacts. 

The technical expertise required in a CSIRT will 
change. CSIRT staff must keep up-to-date with 
new and emerging technologies. 
CSIRTs need to be aware of the constantly 
changing legal framework of the environment in 
which they operate, and adapt accordingly. 

Situations will arise when the resources within an 
unprepared CSIRT may be insufficient to respond 
effectively to meet the conflicting demands placed 
upon it. 

Due to factors such as those detailed in Table 8, the types of incidents reported to a CSIRT, 
priority schemes used, nature of response, and appropriate reporting requirements may very 
well be expected to change over time. CSIRTs must ensure that they have flexible policies 
and procedures to enable the team to easily adapt to changewhether the change results 
from a variation in work load, technical focus, legal issues, or constituency needs. 

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Although these factors are usually outside the direct control of a CSIRT, some level of 
advance planning can ensure that the team is prepared for them: 
  Be prepared to obtain and use external resources to address a crisis (whether extreme 

workload or conflicting priorities), or provide a reduced or revised level of service for the 
duration of the crisis. 

  Undertake continuous staff education or professional development in both current and 

emerging technologies. 

Implement staff training programs. 

 
  Ensure timely access to appropriate information resources. 
  Encourage staff attendance at appropriate technical conferences. 
  Ensure ongoing cooperation with management, legal counsel, and law enforcement (or 

others as appropriate). 

  Ensure that service definitions, policies, and procedures are not so rigorous that they do 

not anticipate and allow for change or unexpected circumstances. 

Most of these issues are explained in more detail in Section 4.2, Fundamental Policies. 

CSIRTs should be flexible enough to meet the demands of their dynamic environment when 
unexpected events arise, but still ensure that such events are handled in a manner consistent 
with the teams overall objectives and operating style. Unless the need for flexibility is 
addressed, the CSIRT guidelines will be too general to provide help and guidance, or too 
restrictive to accommodate unexpected events.  

If changes occur in the CSIRTs mission and operations that will also affect how they interact 
with their constituency, such changes must be communicated to the constituency. 

Example: A CSIRT changes its operation to charge a fee for the services it previously 
provided to the constituency under some other funding model. In such a situation, the 
CSIRT must take appropriate measures to notify the constituency of that fact. 

2.7.2  Legal Issues 

Since none of the authors are legal experts, we can only offer opinions about what we have 
experienced or have seen others experience in this subject area. Our approach here is to bring 
to your attention the issues that you may wish to consider. Readers should check with their 
own legal counsel to identify the issues that are applicable to their own set of circumstances.  

Access to legal advice for CSIRTs is critical; without it, the team can unknowingly take 
inappropriate or illegal actions that can result in the teams demise. Small teams who do not 

CMU/SEI-2003-HB-002 

51 

have easy access to legal advice are at a great disadvantage. They should at least seek legal 
advice prior to beginning service and when making major changes in policy or operating 
procedures, if at all possible. 

Legal issues are a bit like quality assurance: they permeate just about every topic ranging 
from mission statement to operational procedures. This comparison also yields an interesting 
difference: Quality assurance is about saying do-this-and-do-that, whereas legal issues often 
revolve around avoiding doing or saying the wrong things that may make you, your team, or 
your organization liable. Of course assuring a stable legal position is not entirely the art of 
omission; positive action is required as well, such as making sure that possible evidence (for 
example, log files or other artifacts) is properly dated and authenticated. 

Unlike quality assurance, where it is worthwhile to define an overall framework and set up 
measurements, with legal issues this is less feasible. In fact, legal issues are usually tackled 
whenever they apply within a given topic or area. This is not a bad approach for CSIRTs, 
whose core business is incident handling and not the law. The legal issues are boundary 
conditions and should be handled accordingly, in a thorough but pragmatic fashion. That is 
not to say, however, that a haphazard approach should be the outcome; an overview should be 
maintained, possibly by using a fixed set of legal advisors. Seen in this light, the term legal 
issues management is preferable to the commonly used phrase legal advice. 

Institutional issues are comparable with legal issues; only in this case the national or 
international laws are replaced by the laws or regulations that govern the institution of 
which the CSIRT is a part. Clearly these regulations must also be adhered to. The biggest 
difference is liability, which will be virtually absent in the institutional caseunless breaking 
the institutional rules means making the institution liable! 

In the remainder of this section, we will discuss management of legal issues from the CSIRT 
perspective and then focus on the important topics of liability and the main cause of 
liabilitydisclosure of information. 

2.7.2.1  Legal Issues Management 

Management of legal issues involving CSIRT teams means exercising a coherent view of the 
legal issues that the team faces. Legal advice should be given by a fixed set of people (mainly 
legal experts) who are experienced in this area and understand technical terminology and 
issues that form the basis of daily CSIRT work. This set of people (usually only a few or even 
one) should cooperate to ensure a joint coherent view. It is important that legal advisors are 
enlisted for the long haul (years instead of months) because the amount of domain-specific 
knowledge needed by your advisors should not be underestimated. This is especially true if 
you have only one advisor; it will take months to get a replacement up to speed. A very 
practical solution can be to use the legal advisors of your parent organization, but only when 

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these people are experienced enough to guide you through your specific problems. Continuity 
must be assured here as well. If the legal staff does not fit this need, you might be better off 
hiring or retaining a lawyer that better fits your specific requirements, if this is feasible. 

The kind of experience that your legal advisor needs can be derived from the following topic 
areas. These provide examples of the kind of things that the legal advisor will have to look 
into and give advice on: 

Contract Analysis 
All contracts should be checked for legal validity, especially those with customers. This not 
only includes finding statements that are legally meaningless, non-binding or just plain 
wrong, but also identifying omissions that can be legally harmful to the CSIRT. 

Service Definition and Quality Assurance 
The service is what you sell (guarantee, promise, whatever applies) to your constituency. 
Clearly how you define your service and its quality assurance is what you will be held 
accountable for by your constituents, especially when things go wrong. So whatever it says, it 
should be legally sound. 

Policies and Procedures 
Policies and procedures should be checked for legal pitfalls, especially as policies and 
procedures often include statements that involve strong positive action such as sanctions. 
Such actions always inherit the danger of being opposed to some other laws. The following 
examples help to clarify situations in which advance legal advice on a CSIRTs policies and 
procedures would prove beneficial: 

Example: Your policies may say that you are going to fire somebody if he violates your 
disclosure policy. This may very well cause a conflict with local or institutional laws: in 
some countries its trivial to fire an employee, in other countries its very hard. 

Example: Suppose you have stated in your procedures that you will only exchange 
sensitive data with your constituents in an encrypted way. Suppose your constituent is in 
trouble and wants you to fax the data to them. If you refuse, even for the best of reasons, 
although you may comply with your own procedures, it is very doubtful that you are 
meeting your service goals for that constituent. It would be best if you knew in advance 
whether the encryption was a legal requirement or simply a preferred practice. 

Example: Another instance of the above example would be the constituent who does not 
want to support encrypted communication at all and does not have the necessary tools 
available, yet wants to exchange sensitive information. 

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53 

Waivers and Disclaimers 
Disclaimers are found in many places: service descriptions, policies, Web sites, outgoing 
email, etc. All disclaimers should be checked for legal validity, or at least they should have a 
legal purpose. If this is lacking, the disclaimer should be removed. On the other hand, 
disclaimers may be added that have proven their validity in case law. A mythical example of 
an added disclaimer due to case law is the wonderful story about a little dog being warmed 
inside a microwave oven after having come home soaking wet. The dog died, and the oven 
manufacturer was found liable in court. Because of the case, the manufacturer added some 
appropriate phrases to the oven manuals. Or so the myth goes. 

Example: You often read in contracts, on signs in a coatroom, or other places that such-
and-such is in no way accountable for something going wrong (e.g., if your coat is 
stolen). This seems an easy escape but rarely is: often lawyers laugh at such phrases and 
say that its up to the judge to decide. However, on the other hand, these escape clauses 
are not entirely useless; for if they are not there, the case may be even worse from lack of 
due care. 

The CSIRT might require its customers to sign waivers that limit the liability of the CSIRT in 
some way (e.g., best effort, due diligence, or industry standards). Legal advisors may 
be able to suggest areas in which the CSIRT might most appropriately make use of such 
waivers. The same review and caveats that apply to disclaimers should be applied to the 
creation of waivers. 

Non-Disclosure Agreements 
CSIRT staff may be required to sign non-disclosure agreements (NDAs) both when starting 
and leaving employment with the CSIRT. If so, the same will certainly apply to part-time 
staff and visitors who share the details of the CSIRT work. This may also apply to the 
cleaning staff, guards, and others. Just drawing up a non-disclosure agreement and having 
people sign it may be legally ineffective. The signers must understand what the NDA 
encompasses. Before implementing an NDA, it should be reviewed by a legal advisor to 
ensure it is appropriately worded and matches any organizational policies. Without approval 
and review from the legal realm, the NDAs might end up being only a psychological 
safeguard and not valid before a court of law. 

Proactive Measures 
Suppose a law enforcement agency legally requests information from a CSIRT. Is the CSIRT 
prepared for that event and for what may happen afterwards? Suppose the CSIRT is 
summoned for a liability case. Is it prepared for that? Being prepared for such cases 
presupposes two things: 
  doing your job the way that you said you would do it (in your service specifications) and 
demonstrating due care. What due care means also depends on your local laws and 
should be discussed with your legal advisors. 

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  documenting and timestamping all significant events in your workflow and the workflow 

of incidents occurring, within reasonable boundaries 
Example: If your CSIRT only saves logs for a specific time and has stated so publicly, 
and there is no law against this, nobody can complain if logs are not available any more 
once this time has passed. On the other hand, consider the opposite case: imagine that 
after the specific time an audit finds data that should have been deleted much earlier. This 
then might be the foundation of a liability case of its own. 

The second point (documenting and timestamping) is where the proactive measures come in, 
and the legal advisors should advise or provide insight for approaches that support the needs 
of the CSIRT. Essentially the task is to identify the minimum level at which the CSIRT events 
(especially the incidents) should be documented, and also to identify the right way of doing 
this. The minimum is meant as that which is required by law, and that which may be 
required (or come in very handy) in obvious court cases. The right way of doing it means 
that the evidence (the documents, logs, archives, etc.) should be gathered so that it will 
receive high marks for completeness (within the set purpose), logic, and reliability when the 
material is legally requested or is investigated in a court case. This is less trivial than it 
sounds. An example will help clarify this point. 

Example: In a Dutch case (State vs. Ronald O., 1993-5) where an alleged intruder was on 
trial, the evidence put forward by the prosecution included a set of logs. The logs still had 
original page numbers on them, but several pages were missing; they had been discarded 
a long time before by the party from whom the logs came because they contained no 
relevant data. Since pages were missing, the defense pleaded that evidence was being 
withheld. The judge dismissed the defenses plea. However, a better way of handling 
possible evidence (the log files) would have prevented this issue from arising. 

Some people advise keeping all data since archives are cheaper than lawyers. Others tell you 
to dispose of sensitive information as soon as possible so that it cannot be produced even if 
requested. The appropriate answer for each team will depend on the legal jurisdiction that 
they fall under as well as the teams mission. If data is to be kept for possible legal use, 
consider the media that is used to store the information. Media such as CD-ROMs and 
microfiche/film, once generated, are not easily forged and can be produced at relatively low 
costs. Whatever the approach taken by your CSIRT, adequate staff training must be provided 
in this area (such as how to respond if law enforcement wants to seize CSIRT equipment). 

2.7.2.2  Liability 

A liability issue is anything that you say, do, or write; or that you do not say, do, or write; and 
for which people may want to sue you, with a reasonable chance of success in court. In 
countries such as the U.S., this is a reason for grave concern, given the number of liability 
cases and the huge penalties often resulting, which can easily ruin entire firms. In many other 

CMU/SEI-2003-HB-002 

55 

countries, liability is not really an issue unless you have made a big mess of your operations, 
resulting in damage to other parties, such as your constituents. 

The matter of liability is so dependent on local law and so legal in character that your legal 
advisors must be consulted on the subject. Proactive action is needed to prevent liabilities. 
The kind of action needed may vary depending on the context. The context can range from 
liabilities arising from the content of signed contracts (e.g., unable to provide service in line 
with your defined service definition by lack of availability of the service) that a CSIRT has 
with its constituents to those relating to information disclosure or omission. The examples 
supplied in Tables 9-11 illustrate different issues arising from these various contexts. 

Table 9:  Examples of Liability Issues Arising From Omission 

Liability Context: Omission 

Issue 
Lack of information disclosure 

Forgetting about side effects 

Non-recognition of legal 
reporting or archiving 
obligations 

 
 

Example 
You receive log-files that indicate an intruders activities, and you fail to 
follow up on the lead. If this fact is uncovered, you may be liable for failing 
to act on the information. 
You deal with a new vulnerability in a specific incident but neglect to 
notify the vendor and/or other teams of this vulnerability. Then a month later 
the Internet comes to a standstill due to exploitation of the same vulnerability. 
In many countries you are obliged to report to or generate archives for law 
enforcement regarding any case that may involve a serious crime such as 
(intended) murder. This can also apply to crimes such as penetration of 
classified government systems. 

Table 10:  Examples of Liability Issues Arising From the Content of Signed 

Contracts 

Issue 
Inadequate service definition 

Defined service level parameter 
is not met. 
Defined quality parameter is not 
met. 

 

 

 

56 

Liability Context: Content of Signed Contracts 

Example 
Your service is not available during public holidays or only on a limited 
basis; and this is not stated properly inside your contract, or you did not 
define what you mean by holidays. There may be the possibility for your 
constituent to sue you if they experience an intrusion and seek your help 
during that time, but your service is not available. 
You promise your constituents online support that (for whatever reason) was 
not available to a constituent in an emergency situation. 
You do not live up to your promised response time when a constituent calls 
for emergency help during off-hours. If your constituent loses money in such 
a situation, they may well try to get back some of it through you and will not 
settle for an excuse not related to work. 

 

CMU/SEI-2003-HB-002 

Table 11:  Examples of Liability Issues Arising From Information Disclosure 

Liability Context: Information Disclosure 

Issue 
References to individuals or 
organizations 
Revealing identities 

Distributing false information 

Incorrect advice (i.e., 
incomplete, outdated, or just 
wrong) 
 

Example 
You give the impression that a party is involved in an ongoing attack. This 
may damage the reputation and business of the party involved. 
Liability exposure here depends on who is requesting the information. You 
may be liable if you reveal the identity (without prior consent) of victim sites 
to other victims, law enforcement, or the media. But you may not be liable if 
you are required to report the same information to an internal audit. 
You distribute information about a serious bug in operating system XYZ, and 
this turns out to be false information. The vendor of XYZ may not be pleased. 
You inform truthfully about a problem but advise a fix that does not work. If 
this is not obvious and damage results from it, you may be liable. 
You advise a constituent to modify their firewall to solve some problems, but 
your fix silently opens up the LAN to other security problems. 

You present your constituent with information that is seriously outdated when 
better information is already available at sources open to the CSIRT; the team 
member just did not catch up, but your constituent may suffer from this. 

How to limit your liability is again asking for an obvious answer: Do your job right and 
document it. Much about what to do has already been said. The following, however, offers a 
more structured approach to fighting liability and its results: 
  Use standard contracts with legally safe phrases. 
  Remove all statements from your service definitions, quality-of-service levels, and 
policies that may be untrue, difficult (or impossible) to meet, or are legally unclear. 

  Make legally sound disclaimers. 
  Define your workflow, policies, and procedures; and install appropriate documentation, 
enforcement, and control processes such that it is possible at all times to prove that due 
care is taken during your operations. 

Insure your service if the risks exceed the cost. 

 
  Consider using waivers to limit or prevent the CSIRT from being liable for certain 

obligations or damage inflicted on a customer or other CSIRT. 

2.7.2.3  Disclosure of Information 

Information disclosure has the biggest potential of generating liability for a CSIRT. 
Disclosing information is not just about writing reports and advisories; giving advice on the 
telephone is also disclosing information. Apart from these predictable disclosures, there are 
also unpredictable disclosures: 

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legal court orders 

information leaks from the CSIRT (whether from trusted experts or current or former 
employees) 

information gained through intrusion (physically or through the network) 

Several examples of disclosure of information leading to liability have already been 
illustrated in the previous section. It cannot be emphasized enough that these cases of liability 
can be grave indeed, possibly involving huge claims. Some additional interesting examples of 
the possible impact of information disclosure, whether predictable or not, will help this 
understanding: 

Example: If sensitive information about one of your constituents leaks out or is given out 
without thought, this may seriously endanger the security of your constituents site, their 
reputation, or their business. 

Example: If a site is under an ongoing investigation, and a related alert from another site 
is given or leaked to the suspect site, this may warn the suspect and hinder or even ruin 
the investigation. Often the CSIRT will not know about the ongoing investigation, a 
situation that cannot be reasonably anticipated or controlled. The CSIRT could limit its 
exposure to such a situation with an appropriate waiver. 

Preventing information disclosure from creating liabilities is mainly a matter of controlling 
workflow and procedures such that due care is demonstrable at all times (as has been stated 
previously). Clearly the information disclosure policy must be of a restricted type. In other 
words, the policy should say that information should only be handed out on a need-to-know 
basis. 

In most cases the CSIRT defines the terms under which information is disclosed. However, 
the CSIRT may have mandatory reporting requirements placed on it by organizational, local, 
or international relationships (with law enforcement, interest groups such as the Forum of 
Incident Response and Security Teams [FIRST], and others). The requirements and their 
consequences must be clearly understood, because they may affect information disclosure by 
the CSIRT and expose the CSIRT to liabilities. The most common example is that the CSIRT 
must comply to a demand for a report from internal auditors, whereas complying with a 
request from external auditors may or may not be mandatory, depending on the jurisdiction 
under which the CSIRT operates. 

2.7.3 

Institutional Regulations 

Apart from local (and international) laws, your CSIRT will also have to live by the local 
regulations of its parent organization. If these regulations are seen as laws, then most of what 
has been suggested above also holds true for this case. The liability aspect for the team itself 

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may be minimal or absent (making the risks involved in breaking local regulations relatively 
small). However, it may be that breaking these regulations makes the parent organization 
liable. Then the case is the same as above, only with the added complexity of having to deal 
with the parent organization as well. If the risks are high, it is worthwhile creating a legal 
isolation for the CSIRT, such as a separate corporate body. This separation may make the 
risks easier to control. However, it may also pose other problems for the CSIRT when trying 
to interact with other organizational units within the parent organization. 

Examples of institutional regulations are 
  U.S. Department of Energy (DoE) regulations (e.g., CIAC, the CSIRT for DoE, is subject 

to those) 

company regulations (such as those in financial institutions or large corporations) 

 
  military regulations 
 
  other federal or national regulations 

international auditing standards 

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3  Incident Handling Service 

In the previous chapter we discussed an overview of the basic issues that are of concern for 
each CSIRT. We now go on to discuss the mandatory issues related to the incident handling 
service in detail. In this chapter we will describe the fundamental components of an incident 
handling service and the procedures that need to be in place to support them. 

Another insight into the structure of this chapter is to note that any description of the service 
must have at least two dimensions:  
 

specificationthe logical dimension 
A description of the purpose and structure of the service and its functions (Sections 3.1-
3.2) 

 

implementationthe technical dimension 
The actual set of tools, procedures, and roles necessary to implement the specified 
functions in a specified manner (Sections 3.3-3.8) 

We conclude this section with a discussion of two general characteristics of the incident 
handling service (or, for that matter, for any CSIRT service): interactions (Section 3.7 
Interactions) and information handling (Section 3.8 Information Handling). 

3.1  Service Description 

The services offered by a CSIRT should be clearly defined. Each definition needs to be 
understood and available to the CSIRT and the parties with whom it interacts; these 
definitions might be provided at different levels of abstraction. As discussed in Section 2.2, 
Service and Quality Framework, it is important that each service provided by a CSIRT is 
detailed in a corresponding service description. In this section, we will discuss the issues to 
consider when creating an incident handling service description. 

The issues below are ordered logically to facilitate use as a template for filling out a CSIRTs 
service description. However, when considering a description that is to be made available to 
others (e.g., to the CSIRTs constituency), we encourage teams to refer to the results of the 
IETF working group, Guidelines and Recommendations for Incident Processing (GRIP) 
[RFC 2350]. In addition, example descriptions of several service levels from a technical 
perspective (independent from funding issues) can be found within the final report of the 
TERENA Task Force, CERTs in Europe [TERENA 1995]. 

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61 

3.1.1  Objective 

To facilitate the development of its policies and procedures, the CSIRT should have a clear 
definition of its objectives. Continuing with the top-down approach, for example, the 
objectives for the incident handling service will be derived from the CSIRT mission 
statement, which in turn was derived from the mission of the security team, the parent 
organization, or other sponsoring entity. In accordance with the CSIRTs stated objectives, 
the range and extent of functions appropriate to fulfill those objectives can be defined. Table 
12 shows some possible service objectives based on different types of teams with differing 
missions (this is by no means a complete list of service objectives). 

Table 12:  Range of Possible Incident Handling Service Objectives Based on 

Differing Team Types 

CSIRT Type 
International Coordination 
Center 

Nature of Mission 
Obtain a knowledge base with a 
global perspective of computer 
security threats through coordination 
with other CSIRTs. 

National Team 

Maintain a national point of contact 
for computer security threats and 
reduce the number of security 
incidents perpetrated from or 
targeted at systems in that country. 

Network Service Provider 
Team 

Provide a secure environment for 
the connectivity of their customer 
base. Provide an effective response 
to their customers for computer 
security incidents. 

IT Vendor 

Improve the security of its products. 

Corporate Team 

Improve the security of the 
corporations information 
infrastructure and minimize threat of 
damage resulting from attacks and 
intrusions. 

Possible Service Objectives 
Provide technical support in response to 
computer security incidents through 
coordination with other CSIRTs around the 
world. 
Through incident handling activities, seek 
and document technical details of current or 
potential intruder threats. 
Create and disclose information on 
detection, prevention, and recovery from 
intruder threats. 
Provide technical support in response to 
computer security incidents in the national 
language and time zones. 
Provide technical information to detect, 
prevent, and recover from vulnerabilities. 
Act as a liaison to national law enforcement 
agencies. 
Provide technical support in response to 
computer security incidents. 
Ensure the security of the network 
infrastructure. 
Act as a liaison to national teams and/or 
others. 
Provide technical support in response to 
vulnerabilities. Coordinate with CSIRTs to 
analyze the basic source of incidents. 
Create and disclose public alerts about new 
patches and best current practice. 
Provide a center of excellence for incident 
handling support to system and network 
administrators and system users in the 
corporation. 
Provide on-site technical support for 
incidents impacting company systems to 
isolate and recover from intruder threats and 
attacks. 

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3.1.2  Definition 

Before you can describe how your incident handling service can be implemented to achieve 
its purpose, it is important to understand the scope and depth of service that you need to 
provide with the resources available. A good place to start is to identify the issues that will 
constrain the level of service that you can provide. The service provided will be constrained 
not only by the stated objectives of the service, but also by the resources (physical, financial, 
and expertise) available to the team and the teams scope of authority in relation to its 
constituency. There are many different types of incident handling service in existence today. 
The following examples indicate how different services constrained by different limiting 
factors can still provide important roles and achieve useful purposes. 

Example: The most common limiting factor is one of funding, which affects both staffing 
and the physical resources available to run the service. However, many security teams 
that exist today provide a minimal incident handling service consisting of simple 
instantiations of the triage, handling, and feedback functions (see Section 3.2, Service 
Functions Overview) all combined as a single service. 

Example: CSIRTs on the national, organizational, and service provider level with limited 
funding concentrate on the coordinating of activities across their constituencies instead of 
providing detailed or on-site support. These teams play the role of a trusted broker by 
providing a central point of contact to and from their constituency and communicating 
direct incident information to the parties affected by an incident. 

Example: At the other extreme, a CSIRT might have funding for several staff members 
but be unable to attract, obtain, or train staff with the necessary in-depth technical 
expertise. In such a situation, a team might be unable to provide comprehensive incident 
handling service with all functions in place independently. The lack of in-depth technical 
expertise prevents the team from providing an in-depth handling function, i.e., not being 
able to fully grasp what specific incidents are technically about. In this case, the team 
must rely on information generated by other more technically adept teams to use and 
disclose within their own constituency. The limited scope of such a team, e.g., relying on 
the service outputs of other teams, will degrade the service function to just the relaying of 
information. 

With an understanding of the available resources, limiting factors, mechanisms that you may 
be able to leverage from within your existing organizational structure, and the purpose that 
you are trying to achieve, it should be possible to define the incident handling service. To do 
so, bound the level of service that you are able to provide and then impose that level of 
service across the range of functions necessary to provide the service. 

It might be appropriate to produce two resulting service descriptions based on the same set of 
criteria and definitions. One description, for external consumption, would provide 
information such as to whom the service is available, how they would request the service, or 

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63 

the CSIRT support a customer should expect. The other description, for internal consumption, 
would include the external description (the who, how, and what) plus more specific and 
detailed guidance for the internal implementation of the service and how the administration 
of the services is handled in the CSIRT. This latter description could, for example, include 
how the information is tracked and recorded, who is responsible for that function, specified 
approaches for prioritizing requests, and the determination of what exactly is provided to the 
customer within the boundaries of the service descriptions (e.g., there may be circumstances 
when either more or less support is provided, depending on current incident status, 
management direction, or customer funding). From this standpoint, the external description 
should really be developed as an outgrowth or a subset of the internal description. Depending 
on the type of constituency, the whole text might be rewritten for external consumption to 
make it more understandable to people who are not experts in the CSIRT field, or to provide 
additional background information for when service level support might change from 
expected behaviors. 

3.1.3  Function Descriptions 

The incident handling service generally encompasses reporting, analysis, and support (see the 
list of services in Table 4). The service can be further described to encompass four main 
functions: triage, handling, announcement, and feedback. A more detailed description of these 
functions begins with Section 3.3, Triage Function, and continues through Section 3.6, 
Feedback Function. The triage function is like an expert secretary; assessing incoming 
information and passing it on to the right desk (that is, function). The other functions are self-
explanatory and need no further introduction at this stage. 

For each of these (or additional) functions, clear descriptions should be documented for use 
within the CSIRT. These descriptions will assist in the generation of associated procedures. 
Aspects of the individual descriptions will be used to constitute other elements of the overall 
service description that will be made available to the parties that may access the service. 
However, various other implementation details that might be important for internal team use 
may simply confuse external parties, so it is not normally helpful to publish them outside of 
the team. 

The function definitions should at least contain the following information: 
  objective of the function 
 

implementation details and pointers to associated procedures 

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Examples: Is the function only triggered by internal action (i.e., from another function or 
service within the CSIRT) or can it be triggered externally (i.e., by a constituent or other 
party)? How is it triggered or accessed? What forms are used (e.g., email, telephone, 
reporting)? What data is required or desired to flow to or from the function by those 
accessing it? What is the life cycle of events? 

  priority criteria used within the function 
 
 

level(s) of service provided 

expectations setting and quality assurance criteria used 

3.1.4  Availability 

Defining the availability of a service is not just a matter of answering the question Who can 
contact who when? but also under what conditions? 
  Who may access the service? 

Are particular aspects of the service restricted to the declared constituency (such as 
announcements or technical support for incidents) and other aspects available to a 
broader audience (such as accepting incident reports that affect the declared constituency 
from anyone)? 

  Times during which the service is available 

Are different levels of service available at different times? For instance, the feedback 
function might be available only during stated business hours, whereas the handling 
function might be accessible during business hours, or on a 24x7 (24 hours a day, 7 days 
a week) basis for all or some incident types, or to some particular subset of the 
constituency. 

  Conditions under which the service will be provided 

For example, are incident reports accepted only through completion of mandatory 
information requested using the teams reporting forms? 

3.1.5  Quality Assurance 

Users of the service should be provided with information that sets their appropriate 
expectations for use of the service. Differing expectations might be set with other parties. For 
instance, a team is likely to offer greater quality expectations to their funding body and to 
their declared constituency than to other parties. It should be made clear exactly what is 
provided by and what is excluded from the service. It is also reasonable to give some 
indication of the time frame for a response that a user of the service can typically expect. 
Additionally the CSIRT should indicate what the users of the service can expect from the 
CSIRT in terms of handling different types of information provided to it. The expectations set 
should be in harmony with the priority criteria in place for the service. 

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65 

3.1.6 

Interactions and Information Disclosure 

The users of the service need to understand what interactions take place between the CSIRT 
and other parties affected by the service and how information (disclosure) is handled. For 
instance, what can a user of the service expect to happen to any artifacts or log files that they 
supply to the team during an incident? Will these be shared with other teams, vendors, or 
experts, and if so under what conditions will that transfer of information take place and how 
will the information be sanitized and protected? These issues are discussed in more detail in 
Section 3.7, Interactions and Section 3.8, Information Handling, specifically Section 
3.8.8, Information Disclosure. 

3.1.7 

Interfaces with Other Services 

Points and criteria for information flow in the CSIRT between the incident handling service 
and other services with which it interacts depends on what other services the team provides. 
For example, triage is common to many services, and often a single triage function is 
provided for multiple services. 

3.1.8  Priority 

It is important to not only prioritize events within each function of the service, but also to 
understand the relative priorities between the functions that constitute the service and the 
relative priority of the incident handling service and other services offered by the CSIRT. The 
relative priorities assigned will reflect the overall goals and objectives of the team and the 
services offered. If resources are limited, the handling function most commonly takes 
precedence over feedback and announcements. This will also be true if a team is facing a 
dramatic incident rate increase without correspondingly employing additional members of 
staff. Regardless of how the situation arises, the concentration on the handling function will 
leave few resources for other activities, which will be apparent to the constituency. 

Triage, however, is a prerequisite for the handling function to operate effectively. So limited 
triage might take place at a reduced level for all feedback and announcements to keep the 
constituency informed. Until the team can revert to its usual operating state, detailed triage 
effort must be focused on the handling function, and the current operating situation can be 
explained to other requesters to keep them informed. 

Issues of prioritization are discussed in more detail in Section 3.8.6, Prioritization Criteria. 

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3.2  Service Functions Overview 

As stated above, the incident handling service usually includes other activities that support 
the delivery of the service, consisting of the triage, handling, announcement, and feedback 
functions (see Figure 4). These functions and their relationships are explained below and are 
covered in more detail in the next four sections. 

It is important to realize that many CSIRTs exist today that correspond to the functional 
specification portrayed in Figure 4, although they may differ greatly in their implementation. 
The differences occur due to factors such as funding, available expertise, or organizational 
structure. Some of these differences were discussed previously in Section 3.1.2, Definition. 

Example: In a small team, the service functions may not be individually distinct; a single 
person (with the necessary skill set) may provide them for a specific period, handing over 
the task to another team member after that. A larger team may set up a help desk 
composed of staff with a limited range of technical skills to handle the triage and 
feedback functions, and pass the handling function on to staff with a higher technical 
skill set. 

Figure 4: 

Incident Handling Service Functions 

 

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67 

Triage Function 
The triage function provides a single point of contact and the focal point for accepting, 
collecting, sorting, ordering, and passing on incoming information for the service (see 
Section 3.3, Triage Function). In addition, this triage function can be the channel through 
which all external (outgoing) information is passed. It supports different input channels 
suitable to the needs of the team and constituency. An initial priority and possibly an 
associated tracking number are assigned to any apparent new event. As part of the triage 
function, additional actions (such as archiving, translation, or media conversions) can be 
undertaken to make it easier for subsequent incident handling activities. 

Handling Function 
The handling function provides support and guidance related to suspected or confirmed 
computer security incidents, threats, and attacks. This function can include a number of 
different activities. A review of the report (e.g., an incident report) is done to determine what 
occurred and/or the specific type of activity involved. Analysis of the report may include 
reviewing supporting evidence or materials (such as log files) to identify who is involved (or 
needs to be contacted) or the assistance that is requested/provided. The team will need to 
identify the appropriate responses (aligned with the CSIRTs mission/goals/services), and the 
actual notification or follow up with the reporter(s) or constituent(s). This handling is 
described in much more depth in Section 3.4, Handling Function. 

Announcement Function 
The announcement function generates information tailored for the constituency in various 
formats to disclose details of ongoing threats, steps that can be taken to protect against those 
threats, or sanitized trend information on the scope and nature of recent attacks reported to 
the team (see Section 3.5, Announcement Function). For the purpose of this document, the 
scope of this function will be limited to its direct applicability with the incident handling 
service. However, in a CSIRT providing a broader range of services, publishing 
announcements can be considered as a service in its own right and would likely offer a much 
broader range of information derived from other services such as vulnerability or artifact 
analysis. 

Feedback Function 
The feedback function provides support for giving feedback on issues not directly related to 
specific incidents (see Section 3.6, Feedback Function). Feedback can be provided upon 
explicit request (e.g., by the media) or unsolicited, on a regular basis (in annual reports, for 
example), or case-driven (e.g., proactively informing the media). This function will provide 
at least a minimum set of support for frequently asked questions and might be seen as an 
interface for media requests or input to the team at large. 

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3.3  Triage Function 

The goal of this function is to ensure that all information destined for the incident handling 
service is channeled through a single focal point regardless of the method by which it arrives 
(e.g., by email, fax, telephone, or postal service) for appropriate redistribution and handling 
within the service. This goal is commonly achieved by advertising the triage function as the 
single point of contact for the whole incident handling service. If a team wants to limit the 
ability of constituents and others to bypass the triage function, direct contact information for 
individual team members (such as telephone numbers or email addresses) should never be 
given out. 

Because this is a common requirement across many CSIRT services, teams usually advertise 
a single point of contact for the whole CSIRT; and, regardless of the service required, a single 
triage function is provided for all the services that the CSIRT offers. 

Example: Within DFN-CERT, the person undertaking the triage function is called the 
CERT Hotliner. This person is responsible for reading all email to the response teams 
alias, opening all postal mail, reviewing incoming faxes, and answering all telephone 
calls. The DFN-CERT hotline and the personal telephone lines for all other team 
members are forwarded to this persons telephone to ensure that all incident-related calls 
are dealt with centrally. 

specific details on the availability of the defined point of contact 

To stimulate the reporting and the collection of all relevant information, the constituency 
must be provided with easy to use and efficient mechanisms for reporting: 
 
 
 
 
 

supporting documentation (e.g., reporting forms and references to other available 
documentation) for reporter use 

a clearly defined point of contact 

simple but defined procedures to follow 

clear guidelines on the kind of events to report 

Once the information is received by triage, an acknowledgment of receipt will be sent, then 
the information will be sorted, prioritized, tracked, and passed on to other functions within 
the service. Additionally the triage function must decrypt encrypted messages and check 
digital signatures, preserve this information for later use, and allow for actually reading the 
content. To undertake this task, it is necessary for the triage function to have access to the 
data repository used by each of the other functions of the incident handling service. 

Based on the information content and the data in the repository regarding existing service 
events, an initial sorting will take place to identify which function of the incident handling 
service should handle the information. The next step is to determine if the information is 

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69 

directly related to any current or past event. If it is directly related to some existing or 
previously tracked event, it will be tagged as part of that event. Otherwise it will be tracked 
as a new event of a given type and tagged appropriately. In addition to being sorted and 
tagged, the triage function commonly assigns an initial priority to the information in 
accordance with the priority scheme in use by the functions within the service. If information 
enters in the form of hardcopy materials, it is common for the triage function to ensure that 
this information is entered online or a reference made online to the physical location of the 
materials. 

Tools for entering, accessing, and tracking information and events can greatly facilitate and 
semi-automate data manipulation and searches. Such tools can support the staff responsible 
for triage by helping establish the identification of 
  new events (incidents, requests, vulnerability reports, other information notices) 
 
 
 
 

information that is considered out of the scope of the incident handling service 

events that are being tracked separately, but may have a direct relationship 

information directly related to currently tracked events 

information directly related to a previously closed event 

If the information contains insufficient detail or is incomplete, it is likely that the triage 
function will become slow, inaccurate, or incapable of serving its role. In such cases it may 
be necessary to seek more detailed information from the sender before the information can be 
appropriately triaged, which delays the process. In addition to direct tool support for the 
triage function, other steps can be taken to enhance the quality of the information, such as 
tracking numbers, standard reporting forms, and preregistration of contacts. The next three 
sections deal with these topics. 

3.3.1  Use of Tracking Numbers 

If a team uses a tracking number scheme and can encourage or require others to use the 
assigned numbers in all follow-up correspondence, this will greatly facilitate the triage 
process. To facilitate automated support, the numbering scheme should provide simple 
identifiers for human and tool recognition. In a robust tracking system, the tracking numbers 
are the tags that the system uses to automatically sort incoming information and store 
(correlate) it with other related activity, without human intervention at this initial stage. This 
streamlines the process and enables the triage function to focus more intensely on correct 
correlation of untagged information. Tracking numbers can easily be used in the subject line 
of email messages, documented on fax cover sheets, and specified in voice messages. 

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Tracking numbers should be used to track events under each function of the incident handling 
service. Different prefixes might be used for the different services. Since external 
communications have to be considered, part of the number should identify the team owning 
the number. Feedback, incidents, and announcements should each have their own variety of 
tracking number. 

Example: CERT/CC uses the prefix identifiers CERT# for tracking incidents. VU# is 
used for tracking vulnerabilities. INFO# is used for identifying other, lower priority 
information. In addition, other prefixes are used for a variety of internal and external 
documents. 

3.3.1.1  Unique Intra-CSIRT Tracking Numbers 

A fundamental requirement for tracking numbers is that they be unique. Commonly, teams 
allocate numbers from a predefined range of integers as the basis for their numbering scheme. 
Within a teams own incident handling service and preferably across all of their CSIRT 
services (tracking numbers can also be used for other services such as vulnerability handling 
and artifact analysis), a best practice is to use a unique prefix for each function, and also 
ensure that the tracking number following the prefix is unique. If the same number is to be 
used for more than one function, confusion and other difficulties might arise if parties forget 
to provide the prefix and refer just to the number. Ideally, it should not be possible to have 
incident number 60 and feedback number 60. The tag number itself should be sufficient to 
refer to a unique event. If a team plans to reuse numbers, strong controls must be enforced to 
ensure that there is enough time between closing a particular event and reusing its number. 
The delay must make it very unlikely that the number can be misconstrued as pertaining to an 
activity or event previously tracked with that number. 

Example: In 1994 the DFN-CERT used numbers between 1 and 65,535. There were no 
plans to reuse any of these numbers. After four years of operation, approximately 600 
numbers were used. Even with the increased rate of assignment of unique tag numbers, 
there will still be a significant number of years before old numbers will need to be reused 
or a different set of numbers needs to be adopted. 

Example: The CERT/CC also uses a randomly generated set of numbers to track incident 
and vulnerability reports. No incident or vulnerability will receive the same initial 
tracking number, unless the reports are related and cross-referenced or subsequently 
merged into one larger activity. Even then, depending on the nature of the activity, there 
may be references to yet other tracking numbers for other relationships across and 
between activities. With the large volume of reports handled by the CERT/CC, however, 
other supplemental schemes were needed to handle other types of tracking identifiers for 
tracking and assigning reference numbers to other types of information (such as CERT 
Summaries, Information items, CERT Incident Notes and CERT Vulnerability Notes, to 
name a few). 

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71 

Instead of using a limited integer number space for tracking numbers, other approaches have 
been adopted that provide an unlimited number of possible identifiers. Such approaches are 
desirable when the teams involved deal with large constituencies or wish to ensure a 
scaleable approach that will work for several years without the need for procedural changes. 

Example: In early 1994 AusCERT initially used an incident numbering scheme of the 
form YYMMDDHHMM. This was generated from the date and time that AusCERT 
opened the incident. While this addresses the size of the available numbers, it provided 
some other information about the report that was not wantedsuch as how long this 
incident was known to the team and was first identified (or being tracked) by the CSIRT. 
Therefore they adopted another scheme. 

3.3.1.2  Unique Inter-CSIRT Tracking Numbers 

Tracking numbers need to be unique not only within a CSIRT, but also among different 
CSIRT constituencies. As multiple CSIRTs may be involved in responding to an incident, 
they will each use their own identifiers to refer to that incident. If this is not the case, there is 
the possibility that two teams will use the same identifier for different incidents, which could 
lead to confusion and cause delays in providing appropriate responses or feedback. 

Example: Currently both the CERT/CC and the DFN-CERT allocate integer numbers 
within a given integer range for incidents. To ensure uniqueness, both teams provide a 
prefix to indicate their own tracking number. For instance: CERT#12345 and 
DFN-CERT#12345 are two separate and unique tracking numbers that refer to two totally 
unrelated incidents.22 For todays teams, it is a generally accepted best practice to record 
all numbers for all teams involved when exchanging correspondence or other information 
about CSIRT activity with other teams. It greatly facilitates the identification, tracking, 
and correlation across such events. 

If a teams tools support recognition of various tracking number formats used by different 
teams, it will further facilitate the triage function. Teams are encouraged to reference each of 
the tracking numbers of other involved teams during their communications on related events 
to allow efficient identification and processing by all. 

3.3.1.3  Tracking Numbers are Public Information 

Because tracking numbers are used in the teams external communications, they should be 
considered as public information and hence should not disclose sensitive information such as 
the names of hosts or domains involved. Other sensitive information to avoid in a tracking 
scheme includes information that would indicate the number, nature, or scope of events 

                                                 
22 

It is possible that each team, through coincidence, may have its random number generator issue 
the identical number for related incident reports. In practice this is unlikely to occur; and even if it 
did, the use of the prefix would clearly identify the relationship of the activity to each CSIRT. 

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(particularly in the case of incidents) reported. For these reasons, use of some random-
number-generating scheme is a better practice. 

3.3.1.4  Tracking Number Life Cycle 

The life cycle of tracking numbers also needs to be considered. If an identifier is used to track 
an event, then it is usually the case that the tracking number initially allocated will remain 
with that event from the point at which the event is identified until the event is handled from 
the teams perspective and is considered closed. But there are situations that arise that do not 
fit such a simple model and need consideration, such as: 
 

Information is incorrectly triaged: 
Triage may incorrectly identify an event as new when it is in fact directly related to some 
other event. 

 

Information is incorrectly tagged: 
Information may arrive with an incorrect tracking number and as a result be tracked 
inappropriately. 

  An event is reopened: 

If an event is closed and new information arrives for that event, then the event will be 
reopened. 

  Events merge: 

New information arrives that directly links two events that were previously tracked 
separately. This is difficult to archive. All incidents should be appropriately cross-
referenced. Whenever incidents appear to be related they should be analyzed in more 
detail to determine if both incidents should be merged or not.23 

3.3.2  Use of Standard Reporting Forms 

The use of standard reporting forms will facilitate the provision of complete and appropriate 
information being supplied to the team by parties reporting to it. This also facilitates the 
timely identification of new reports with associated activity and routing of information to the 
right function. It also improves completeness and comprehensibility of initial 
communications, which makes further processing easier. For most services, useful forms can 
be designed and implemented for use by the constituency or others (e.g., vulnerability 
reporting forms within a vulnerability handling service). 

                                                 
23   Note: Even if they are merged, the issue of which identifier to must be consideredif many 

different sites are involved (and the incidents were formerly tracked separately), it can be complex 
to manage the overall event.  In such cases, the original tracking identifier and a new merged 
identifying number may be used; alternatively a completely new number may be assigned once all 
the individual reports are merged.  In either case, the affected parties (sites, constituents, etc.) will 
need to be notified and requested to use the appropriate tracking identifier.  While the CSIRT may 
ask them to do this, recognize that there is no guarantee that the affected sites/constituent members 
will do so. 

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73 

Within the incident handling service, forms may be made available for reporting incidents 
and for making information requests. To be of use, these forms need to be as clear and 
concise as possible and readily available for people to use when required. In support of both 
the triage function (in determining the relationship of the report to currently tracked 
activities) and the handling function itself, incident reporting forms commonly request the 
following types of information:24 
 

contact information for the reporting site and any other parties communicating in 
response to the incident 

  names and network addresses of hosts involved in the incident 
 
  description of the activity and relevant information (such as logs, associated time-zone 

the nature of the activity 

information, and other artifacts) 

 

tracking numbers that may have already been assigned (by a local security team or 
another CSIRT) 
Example: During a coordination effort, logs from one attacked machine are submitted to 
the CSIRT by a reporting site. The logs are of the form: 

Mar 2 02 10:34:12 myhost tcpd[52345]. connect REFUSED from cumber.some.where 

Without knowing the corresponding time zone for the above log, the team will be unable 
to provide the administrator of cumber.some.where with enough information to 
enable them to check their local logs for users that were logged in around this time. This 
problem is further exacerbated in international environments or countries with multiple 
time zones, as the possible time frame for the activity broadens. 

Sometimes teams have trouble convincing people of the need to make a report in the first 
place. If some prospective reporters feel that the reporting form is cumbersome and not very 
effective, they may be more reluctant to report an incident. A team might choose the risk of 
losing some initial information in preference to not obtaining a report at all and let their 
constituency call or send information in free form (unformatted). The effects of this, 
however, mean the CSIRT staff will need more resources (time) to extract relevant 
information from such reports and enter it into the CSIRT tracking system. If forms are 
provided they must be as clear and concise as possible and must allow for easy reporting. 
This also applies for the number of forms used by one team. Consider whether it might be 
possible to use one basic reporting form or template that constituents can use to report a 
variety of different problems, requests, or other information to the CSIRT. In addition to 
providing forms and expecting the constituency to use them, the team must raise the 
awareness of the benefits of form use and must encourage people to report using forms.  
                                                 
24   These are excerpted from the CERT/CC incident reporting form [CERT/CC 1997a]. A more recent 

incident reporting form (as an online reporting form or in text version) is also available at 
<http://www.cert.org/nav/index_red.html>. 

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3.3.3  Preregistration of Contact Information 

In addition to the use of reporting forms, depending on the size and nature of a teams 
constituency, it may be possible to take some proactive steps to solicit information in advance 
that will be helpful to the triage function (as well as other functions comprising the incident 
handling service). This process can also be extended to solicit information in advance from 
other parties, such as other CSIRTs, law enforcement, etc. Such a registration process can 
help to prevent the need for standard questions to be handled on a case-by-case basis for 
every new report/request.25 Useful items to preregister include, for example: 
 

trusted points of contact and associated contact information (must be routinely verified, 
at least once a year) 

 
 

information disclosure restrictions 

(verified) keys for encrypted and/or signed exchange of information 

In some cases it may be useful to preregister other information such as domains or time-zone 
information for the site. But this will depend on whether or not the hosts covered are located 
in the same time zone as the registered contacts. 

Example: Given the (numerically) small and well-defined scale of its constituency in 
1994, AusCERT initially established a constituency registration process as detailed in 
Forming an Incident Response Team [Smith 1994]. This process included establishing 
trusted points of contact and information disclosure restrictions. AusCERT later changed 
this process when it became a fee-for-service team, but kept the same underlying concept 
of obtaining as much contact information as possible from its subscribers. 

Example: CERT-NL serves a constituency defined by contract (between a national 
research network as the Internet service provider and its customer sites) and therefore can 
support a registration process for site security contacts and cryptographic keys to allow 
confidential and authentic email communication. Furthermore, because its constituency is 
of the academic type, CERT-NL is able to uphold a default information disclosure policy. 

Example: Because the CERT/CC has such a broad-based constituency, it is not possible 
to obtain this type of preregistration contact information from every potential reporter. 
However, the team does have such details for regular reporters or those with whom the 
team interacts (such as trusted experts, sponsors, vendors, etc.). 

                                                 
25   Kossakowski, Klaus-Peter. The Role of Site Security Contacts. 7th Workshop on Computer 

Security Incident Handling, Forum of Incident Response and Security Teams, Karlsruhe, 
Germany, September 1995. 

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3.4  Handling Function 

The goal of this function is to provide response and support for reports received from the 
constituency (and possibly others). At a minimum, the function should provide some 
instantiation of the following attributes: 
  Reporting point: A location for receipt of incident reports pertaining to its constituency 
  Analysis: Some level of verification of the report and technical understanding of the 
activity. This will include identifying the appropriate responses that will be provided 
under the notification attribute. 

  Notification: Passing appropriate response/recovery information to (at a minimum) 

constituents and preferably other affected sites and CSIRTs 

The definition of the term response will vary from team to team based on the teams 
definition of an incident and the objectives of the individual teams incident handling service. 
In addition, other factors need to be considered, the most important of them being the priority 
assigned to a specific incident report and the relationship to the sites involved (e.g., if they 
belong to the constituency of the individual team or some other affected site). 

Table 13 lists some possible instantiations of the functions necessary to carry out the handling 
service. 

Table 13:  Possible Instantiations of Handling Function Attributes 
Attribute 
Reporting Point 

Possible Instantiation 
  Deal with incoming reports that affect the constituency and pass them on (as 

Analysis 

Notification 

appropriate) to the sites affected within the constituency 

  Deal with reports from the constituency that affect sites and CSIRTs external to the 

constituency, and pass them on accordingly 

  Both of the above 
 
Examine log files 
 
Identify affected sites 
 
Point to technical documents or advisories 
 
Provide technical support 
 
Provide workarounds and fixes 
 
Provide on-site assistance 
 
 
  Undertake contact of other parties affected in the incident 
  Undertake contact of other parties affected and law enforcement 

Point to resources that provide or can help establish appropriate points of contact 
Provide a list of appropriate points of contact 

Before talking about analysis in more detail, it is helpful to have an overview of the life cycle 
of an incident from an initial report through analysis to notification and closure. In order to 

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be able to perform the incident analysis function well, a set of specific information must be 
tracked. This is also discussed in this section. 

3.4.1 

Incident Life Cycle 

Whatever a teams definition of an incident may be, it will likely conform to the life cycle 
described in this section. As mentioned in Section 3.3, Triage Function, part of the life 
cycle of an incident may take place within the triage function, where an incident can be 
initially categorized, identified as a new event to track or as part of some existing incident 
already being tracked. The appropriate tracking number is assigned to it (either a new 
tracking number or the number for an activity already being tracked and to which it belongs). 
Note that a new incident can also be identified during the handling function as a result of 
incorrectly triaged information, information provided to the team under an incorrect tracking 
number, or new information being discovered as a result of more in-depth technical analysis. 
Figure 5 provides an illustration for the CERT/CC incident handling life-cycle process. This 
is described in more detail in the following paragraphs. 

 

Figure 5:  CERT/CC Incident Handling Life Cycle 

Once an incident is opened, it may transition through many different states, with all the 
information relating to the incident (its change of state and associated actions) until no further 
action is required from the teams perspective (the circle portion of the life-cycle 
illustration) and the incident is finally closed. It is also important to note that an incident (or 
event) can cycle through the analysis portion multiple times during the activitys life cycle.26 

The closing of an incident normally occurs when none of the parties involved in the incident 
are identifying or reporting new information to the CSIRT and the CSIRT has undertaken its 
actions of appropriately responding to all parties affected by the activity. A team might also 
close an incident even if new reports are anticipated, but it makes no sense to follow up 
further (e.g., if there is nothing more the team can do). 

                                                 
26   This CERT/CC Incident Handling Life Cycle graphic is extracted from the CSIRT training courses 

(see <http://www.cert.org/training/>).  

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77 

Example: A CSIRT continues to receive more external notices of virus reports. The virus 
report has already been received, analyzed, and handled. Appropriate notification has 
been made available to the CSIRTs constituency. There is nothing new to be gained by 
further analysis. The incident is closed. 

Example: A company CSIRT may not close an incident until any legal case associated 
with it is completed. 

Example: A coordinating CSIRT serving a large constituency may close an incident if no 
further technical support is needed by the sites involved in the incident. 

As a result, the criteria for closing an incident can vary from team to team.  

It is equally important to note that, even if a team closes an incident, a site involved may still 
consider the incident open if they remain involved in resolving the incident, are preparing to 
recover their systems, or are involved in a court case against the perpetrator. In the latter case, 
if the CSIRT is a coordinating team with a broad constituency (say a country-level team), the 
CSIRT may not be involved in the legal proceedings that are being pursued by an affected 
site. 

During its life cycle, an incident may transition through many different states, such as 
 
  waiting: The team is waiting for a response from other parties external to the team. 

action required: Actions are required by the team in response to the incident. 

When a CSIRT decides to close an incident, it should ensure that all of the affected parties are 
being or have been informed of the closure. This will help to set the appropriate expectation 
and avoid confusion in cases where someone thinks the incident is still open and wonders 
why they hear nothing further from the CSIRT. The team can either separately inform all 
parties involved when they close the incident or inform parties during ongoing incident 
correspondence. The former is more time consuming and is likely to generate a flurry of 
trivial email responses, or may result in someone finally providing a response that causes the 
incident to go back into an action required state. The latter encourages correspondents to 
provide information in a more timely fashion and is a more effective use of the often limited 
CSIRT resources. 

Example: In previous years when there was more direct one-on-one incident response, 
the CERT/CC incident handlers would tell contacted sites that if no further feedback was 
provided by the correspondent by a specified date, their thread of the incident would be 
considered closed by CERT/CC.27 

                                                 
27   More recently, the CERT/CC focuses on a more strategic coordinating role of helping many (one-

to-many) so less direct interaction with the end user occurs. Depending on the type of incident 

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Closed incidents may need to be reopened if new information is made available to the team, 
such as a report of rekindled activity at one of the sites involved. When the need arises to 
reopen an incident, the original tracking number should be reused, if possible.28 However, if 
the activity is not considered to be a continuation of the original incident/report, it is 
appropriate to generate a new incident for the activity and issue a new tracking number.  

Similarly, as mentioned earlier, new information may become available that directly links two 
or more incidents that previously appeared to be unrelated. In such cases, a team needs to 
decide if the incidents should be merged into one (if so, identify which tracking number 
should be used and who should be informed of it) or if they should remain as separate 
incidents and marked as related. Whatever scheme is adopted, all procedures, tools, and 
databases that might be affected will need to be capable of supporting such events. Such 
technical problems can be solved, but the human issues are not so trivial to solve and need to 
be taken into account. Unfortunately, even after an incident has been renumbered or closed, 
you may find someone replying to an old message containing an out-of-date tracking number 
to report completely new activity. 

3.4.2 

Incident Analysis 

During the life cycle of any incident, analysis provides information that plays a major role in 
the decision-making process and next steps to take in accordance with a teams policies and 
procedures.  

The first instance of incident analysis actually takes place during the triage function, 
occurring whenever new information comes in; this kind of analysis has been covered already 
and is not the topic of this section. Here we will focus on the more in-depth technical analysis 
of log files, malicious code, and incident texture. 

Example: Consider an analogy with a hospital emergency unit. The triage function 
initially decides which incoming patient goes where (e.g., the first initial high-level 
analysis). Then more comprehensive analysis aspects come next, such as blood tests, 
scans, EKGs, and X-rays. The results of these tests help determine the next actions, such 
as medicine and/or surgery. 

                                                                                                                                           

handled, the CERT/CC may keep a report open and continue to solicit additional information 
from correspondents. (It should be noted that the general auto-responder message from the 
CERT/CC infers that with the heavy incident load, not every incident report will receive 
individual follow-up.) 

28   Unfortunately, some trouble-ticketing systems will not allow ticket numbers to be reopened once 

closed. 

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79 

Different types of analysis can be CSIRT services in their own right, separate from the 
incident handling service. One could, for example, offer an artifact handling service, 
additional to (or even totally separate from) the incident handling service.29  

Artifacts can be found in the remnants of intruders activities. Searching for and analyzing 
artifacts, followed by neutralizing them as cost effectively as possible, is a craft of its own. A 
discussion of such separate services is not the goal of this section. However, since artifacts 
are often discovered during incident handling and since artifact analysis often is part of 
incident handling to some extent, reference will be made to artifact topics as appropriate, but 
not in any great detail. 

There are two general classes of incident analysis to consider: 
 

Intra-Incident Analysis 
Analysis of the issues concerning a specific incident. The most common types are as 
follows: 
  analysis of any artifacts left by intruder activities (log files, exploits, viruses, Trojan 

 

horse programs, toolkits, etc.) 

  analysis of the software environment in which the incident took place 
  analysis of the web-of-trust within an incident 
Inter-Incident Analysis 
Analysis of issues concerning relationships across and between incidents, that is, the analysis 
of the texture of ongoing incidents. This analysis is aimed at finding symmetries between 
separate incidents that might indicate equivalent or related sources of intruder activity. 

Analysis is a very large topic area. We have chosen to cover it in detail in this chapter 
because a good analysis is critical to the provision of a competent incident handling service. 
We begin with a discussion of the importance of an overall analysis review (the bigger 
picture) and issues that affect the depth of the analysis undertaken. 

3.4.2.1  The Bigger Picture 

It is important to retain an overall grasp of all analysis resultsthe bigger picture. The bigger 
picture is largely concerned with trends (possible types of future attacks, security 
improvement), statistics (e.g., number of hosts involved, rate of incident reports), and case 
studies (e.g., understanding the intruder community or the impact on specific systems and 
applications). Each CSIRT will build its own bigger picture that is most relevant to its 
constituency. 

                                                 
29  The CERT/CC has chosen to do this. See the CERT/CC Overview of Incident Trends 

presentation at  http://www.cert.org/present/cert-overview-trends/module-1.pdf. 

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Obtaining this bigger picture can be difficult, as different staff may be assigned to tackle 
different types of analysis. Various people within the team will have different pieces of 
information resulting from their piece of the analysis. To obtain the bigger picture from the 
information available to the whole team, it is important to institute a process to collate the 
information. This can be accomplished by team members interacting in regular meetings or 
ensuring that incident supervisors obtain the information from team members. 

Refining the bigger picture is especially useful in identifying lessons learned and so can help 
to improve response to future incidents. By studying lessons learned and experience as the 
result of handling incidents over time, the case history information obtained will often help 
staff to make the right decisions in the future, and sooner. Implementing a knowledge base to 
assist in this process can be a great help, especially for continuitys sake, since unlike 
personnel, knowledge bases neither change employers nor have holidays. Case studies can 
also be an excellent learning tool for new CSIRT staff members. 

Example: The following shows how insight into the bigger picture can be provided through 
access to a good case history. As the result of both intra- and inter-incident analysis, it was 
noticed that on several occasions incidents had been identified where compromised systems 
had a combination of a certain weird directory name along with a Trojan-horse program 
located elsewhere in the file system. The next time this weird directory name was found, it 
prompted the team to search for the associated Trojan horse immediately. 

It is useful and advisable to make the (appropriately sanitized) bigger picture available to 
other teams and possibly law enforcement.30 This can be done in the form of free text news 
flashes or a common format for disclosure. A common format has not yet been adopted for 
use in the CSIRT community. Additionally, a team might choose to publish such reports to 
their constituency through their announcement function to keep the constituency in the loop, 
raise awareness, and provide insights into new trends and developments (see Section 3.5, 
Announcement Function). Along other lines, there is effort underway to seek more 
formalized ways to represent data (see for example, the TERENAs Incident Object 
Description and Exchange Format Requirements [RFC 3067]). The goal of this work is to 
ultimately provide a common data format for the description, archiving and exchange of 
information about incidents between CSIRTs...including alert, incident in investigation, 
archiving, statistics, reporting, etc. 

3.4.2.2  Analysis Depth 

To what level of detail should the analysis be undertaken and what level of resources should a 
team expend when analyzing incidents? Analysis depth depends on a range of factors. Some 
examples are given in Table 14. 
                                                 
30   Carpenter, Jeffrey J., Dunphy, Brian P. Moving Towards the Exchange of Incident Statistical 
Data. 10th Annual FIRST Conference on Computer Security Incident Handling and Response, 
Forum of Incident Response and Security Teams, Monterrey, Mexico, June 1998. 

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Table 14:  Analysis Depth Factors 
Analysis Depth Factor 
Teams mission and 
technical capabilities 

Description 
A team whose mission is to safeguard the security of their constituents will have to 
go to great lengths to investigate ongoing incidents in a thorough way. The team will 
need the technical capabilities to do so. If capabilities in a certain area are lacking, it 
will result in less detailed analysis. In such cases, the analysis for that area could be 
subcontracted.31 
When there is sufficient funding and staff resources available, incidents of lower 
priority might be investigated more often and to greater extent. On the other hand 
teams with limited funding or staff resources will need to be very selective about the 
depth of any analysis undertaken and will most likely focus on high priority 
incidents. 
If it is likely that the intruder will strike again at another time or place, it is 
worthwhile spending time analyzing the incident. Investigating the incident will 
reduce the impact that might result from repetition of the incident by providing 
relevant information to constituents, other teams, and possibly also law enforcement. 
The analysis of such incidents may also be of use internally, keeping other team 
members aware of the bigger picture. 
There is little point in analyzing an incident in great detail if the activities exhibited 
by the intruder and the tools and methods used are commonly known (there will be 
nothing new for the team to learn from the analysis). However, if it is suspected that 
the intruder is using a new method of attack or a new variant of an existing method or 
tool, then in-depth analysis is necessary to understand the activity. 
If a site reports an incident but does not provide the information needed to perform a 
detailed analysis, this might effectively stop any further analysis. 

Severity of the incident 

Chance of repetition 

Possibility of identifying 
new activity 

Support from constituents 

examine log files 

actively resolve problems 

There is a whole range of actions that a CSIRT can take if it has the time to both analyze 
events thoroughly and appropriately disclose the results to its constituents and to other teams. 
A list of possible actions in order of increasing resource demand is 
 
 
  provide workarounds or fixes 
 
 

examine malicious code and software environment 

examine site security, in conjunction with the sites network (trust) relations 
Example: A team might use a commercial vulnerability scanner to actively investigate if 
there are no obvious holes in the sites host systems, seen from internal (intranet) and 
external (the Internet) perspectives. Checking the security posture of a site in this way is 
fairly easy to do. But such activities must have management approval and need to abide 
by policies and procedures of the team and site to avoid any misunderstandings that 
imply that the team broke into a site. Such activities will consume a great deal of time 
because the results will need to be analyzed by the team very carefully to avoid any 
liability for overlooked security weaknesses. 

                                                 
31   See Outsourcing Managed Security Services on the CERT/CC Web site at 

http://www.cert.org/security-improvement/modules/omss/. 

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3.4.2.3  Log-File Analysis 

Every decent hardware platform and operating system and many programs (especially server 
type software) provide the facility for alarms and logs. Alarms are triggers designed to draw 
attention when some predefined (usually undesirable) event takes place, such as a packet 
flood. Logs are files in which events (both harmful and innocent) are recorded. Alarms ring 
when a specific log entry meets predefined alarm criteria. 

Alarms are mainly of interest to the operators in question, whereas logs generate a wider 
interest, mainly because of their portability and wealth of detail. Log files can provide 
information such as 
  who logged in when from where 
  what kind of login occurred (SSH, telnet, rlogin, X, etc.) 
 
  what errors occurred 

to what destinations email was sent 

It is up to the operators of the systems involved to ensure their logs provide the necessary 
level of detail. Clearly an incident handling service can give advice here, during the course of 
an incident, but also in a preventive way by telling the constituency about good log-file 
practice. It is up to the CSIRTs to accept relevant logs, process them, and act on the results. 

Changes within the DNS system may take place so that host names or IP addresses are no 
longer valid or point to different hosts. So if log files are to be of any more than just 
incidental use, they must display certain characteristics (see Table 15) and must be analyzed 
as soon as possible. In addition, the full value of the logs may only be realized when 
reviewed alongside the configuration files (like /etc/syslog.conf) of the tool that generated 
them. 

Acceptance, receipt, and processing of log files involves some generic issues for the CSIRT 
to consider; these are discussed below. Additionally, all material within the premises of the 
CSIRT must be protected (see Section 3.8.4, Information Storage). Of similar importance is 
to carefully dispose of all material that is no longer needed or in use (see Section 3.8.5, 
Information Sanitizing and Disposal). 

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Table 15:  Notable Characteristics of Log Files 
Characteristic 
Timestamps 

Origin of Log 

Authentication of Log 

Description 
Timestamps must be present in the log for virtually every internal event recorded. Use 
of time-synchronizing software like NTP (Network Time Protocol) is strongly advised 
to avoid confusion when comparing logs from different sites (or even different 
machines from the same site). For the same reason, timestamps should include time-
zone information. 
All details about the machine (Internet name, network address, machine type) that 
produced the log must be collected. It is also important to know what software 
(including version number) was used to generate the log and any associated 
configuration files. 
Without authentication, it is not possible to say if a log file is authentic and wasnt 
created after the event in question or tampered with before the activity was discovered. 
(After all, logs are still mainly text files that anyone can produce with their favorite 
text editor on any computer platform.) Under some laws, it is advisable to let two 
people date and sign important log files (i.e., on printed versions of the log files), 
preferably on the same day that the log was produced. Such actions are mainly of 
interest if legal action is possible. Another alternative approach is to have logs written 
to another host machine with very controlled access. 

Categorization 
What category (secret or public) does the log file belong to? There should be a policy on 
categorization of information to be applied by the triage function, and subsequently the 
information should be handled appropriate to its category. 

In the case of log files, it is often necessary to attach more than one category to one log. 
Generic information is generally less sensitive than specific information revealing machine 
names, network addresses, and names of employees. 

Example: IP sniffer logs can commonly contain any information, ranging from not 
sensitive at all to explicit username/password combinations, as well as emails and their 
attachments. 

A broad categorization of the log file must usually be done before the log is actually obtained, 
because the category (based on the apparent information in it) may impose boundary 
conditions on the way the team receives the log and what they can do with it. 

Receiving 
The log should be delivered to the team with the necessary level of due care corresponding to 
the category of the log information. Sensitive information must be transferred in a safe way 
(e.g., using encrypted channels), whereas non-sensitive information can be transferred in 
plain text using email. Sending the log files on disk or tape might be appropriate if larger 
amounts cannot be transferred encrypted over the network. 

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Verifying 
Is the log file genuine? An authentication method should be agreed on with the party sending 
the report. Digital signatures provide a solution to this problem, with MD5 and RSA being 
popular algorithms/protocols to implement this. Whereas MD5 (a checksum algorithm) only 
ensures that the data received equals the data sent, RSA (a public key algorithm) helps in 
establishing the identity of the sending party and the authenticity of the data received. No 
method, however, can 100% verify that a log has not previously been tampered with by either 
an intruder or some other party. 

Cleansing 
Sensitive but irrelevant information is often best disposed of or sanitized immediately, to 
eradicate any possibility of disclosure. 

Example: Often passwords can be removed from incoming logs immediately. Password 
information is seldom of much use to a CSIRT, but you dont want it to leak out. You 
may ask the parties involved changing all passwords, but this often takes much time, and 
some constituents will not even comply. So its best to avoid unnecessary risk. The 
original log must remain unchanged, as it might be of use during a legal investigation.32 

Disclosing Log Extracts 
If incident follow-up is undertaken and other constituents and teams are to be informed about 
the activity and the part of the incident that relates to them, it will usually be necessary to 
send them information from the log files. As a rule, complete and unabridged log files will 
not be sent out. Relevant extracts will be produced and sent to the parties involved, 
containing only those details that are specifically relevant to them. 

3.4.2.4  Artifact Analysis 

Intruders often leave all sorts of files on the systems that they compromise. These can range 
from Ethernet sniffer log files, password files, exploit scripts, source code to various 
programs and other tools. Generically we label these remnant files. We address scripts, source 
code (malicious code), and other programs of a potential malicious intent as artifacts. Some 
of these files may not be at all malicious, but we dont know that until they have been 
analyzed. The correct default assumption to make is that an artifact script or program is 
malicious until proven otherwise. 

Intruders may have replaced ordinary files by others that differ in content from the original, 
but not in name. These Trojan-horse programs are popular among intruders. They are 
programs that seem to do everything the original program was intended to do, but that do it 
the wrong wayor (even worse) do what the original program was supposed to do and also 

                                                 
32   This is actually a very dated example, but given the still widespread use of cleartext password 

protocols like FTP and POP3, as well as Basic Authentication for HTTP, this example still applies. 

CMU/SEI-2003-HB-002 

85 

do something else (e.g., updating the intruder on what is happening, sending sensitive 
information to a hidden log, or forwarding information to other external destinations). 

A Trojan-horse version of a telnet daemon may log the username/password combinations that 
people are typing and send these logs to the intruder by email or store them somewhere on 
disk for the intruder to fetch. You cannot definitively identify fake programs such as Trojan 
horses by file attributes such as date or size. Intruders go to great pains to make the Trojan 
horse identical to the original program with respect to all file system attributes except 
content, meaning that only a proper cryptographic checksum analysis can detect a difference 
between files. Keeping off-line, read-only lists of checksums of system files and important 
programs is therefore a good practice (unless you favor reinstalling your systems from 
scratch after even a minor intrusion). Programs such as Tripwire33 and anti-virus programs 
such as ThunderByte make lists of this type part of their routine and inform you when the 
checksum on a file has changed. 

Whether or not the CSIRT should analyze malicious code as part of their incident handling 
service (or as a separate service) is an important question to answer. Various CSIRTs have 
differing views. The following examples are from different extremes. 

Example: Some teams do not have the resident expertise to analyze malicious code and 
must rely on other CSIRTs or experts to provide such analysis. 

Example: Commercial teams who have taken on the job of securing a sites network will 
usually fully investigate the matter, including analysis of malicious code if required. 

No matter who performs the task, proper analysis of malicious code should be addressed to 
some extent. How else is one going to derive an intruders fingerprint, which may help in 
analyzing other incidents? How else does one know in what directions to seek further, if not 
by actually observing what the code tries to do? Just eradicating all artifacts and building the 
system from scratch is a very expensive solution to an intrusion. And it is often a very naive 
one, especially if the flaw that enabled the intrusion in the first place has not been removed. 
Artifact analysis can help by understanding what the artifact does, for inside the artifacts 
lurks the intruder. 

Assuming the CSIRT takes the responsibility of analyzing malicious code as part of the 
incident handling service, the following points should be considered. 

Where to analyze the artifacts? 
Usually the malicious code will not be analyzed on the victims systems. The constituent will 

                                                 
33   Tripwire is available commercially from http://www.tripwire.com/. A publicly available version 

is available from ftp://ftp.cerias.purdue.edu/pub/tools/unix/ids/tripwire/. 

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want to return to normal operation as soon as possible, and you dont want to further 
endanger the constituents environment. From the intruders point of view, what is simpler 
than writing a piece of malicious code that attempts to destroy the information on the hard 
disk if the code is invoked in the wrong way? 

Care should be taken to make a copy of the artifact(s) plus surroundings that, where possible, 
exactly mirror the original environment. This should not be performed by the constituent just 
sending some files, but by a member of the CSIRT or some other informed and authorized 
individual. This means the constituent might grant the team member temporary access to the 
system involved, or undertake the task themselves using instructions and guidance provided 
by the CSIRT staff. 

Ideally the artifacts are analyzed in an isolated laboratory, isolated in a networking sense. Test 
computer equipment and a test network environment should be available for artifact analysis. 
Also, total loss of the test environments data should be of no consequence. If the test 
environment must be accessible from the outside for practical reasons, this should only be 
possible through a very restrictive firewall. 

Example: Several response teams tested a flaw in INND (a netnews daemon) in 
production (e.g., not isolated) environments. This resulted in News control messages 
escaping from their test systems and doing what they are supposed to do inside NNTP,34 
i.e., spread all over the world. Unfortunately these control messages exploited the INND 
flaw in such a way that /etc/passwd files were sent to specified email addresses (in this 
case the CSIRT teams doing the testing). Thousands of such messages were received. 
Had the teams used appropriate isolated laboratory environments, this would not have 
occurred. 

When to involve expert groups? 
Given the size of the average CSIRT, it is most likely impossible for each team to know 
everything about every operating system version and network protocol. Therefore it is often 
advisable and even desirable to share the analysis process with some other group of experts. 
Because of the sensitivity of the work, and depending on the nature of the CSIRT and its 
constituents, these experts should be identified in advance and appropriate precautions taken 
(e.g., screening or non-disclosure agreements) before any information or analysis is shared or 
undertaken. 

Example: CERT-NL has an expert group associated with it. This is a voluntary effort by 
experts from the CERT-NL constituency. The experts benefit by receiving new 
information first-hand. CERT-NL benefits by obtaining feedback from the experts. 

                                                 
34   The News protocol. 

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87 

Example: There are times when more mature teams cooperate when performing analysis 
(mostly vulnerability analysis or artifact analysis), with one team taking the lead and the 
others contributing as experts. 

When to stop? 
Criteria should be defined in advance for determining the limit of depth and breadth of the 
analysis before it is stopped or transferred to another entity (e.g., a separate artifact analysis 
service). Such bounds can be as trivial as a limit on the amount of staff effort spent, or they 
can be based on an evolving assessment of the problems complexity. 

3.4.2.5  Analysis of Software Environment 

Just analyzing Trojan-horse programs, Ethernet sniffer logs, and exploit scripts (i.e., artifact 
analysis) is not enough. Study of the environment in which these remnants were found is of 
equal importance to solve the puzzle and see the bigger picture. Take for instance an exploit 
script. The success of such a script is determined by its surroundings: the shell environment, 
the software present, available privileges, and so forth. 

Operational systems are made up of tens of active programs and drivers and hundreds of 
ready-to-run programs. The file system is usually complex, with rights distributed in a semi-
random way to numerous users and groups. An exploit script itself is relatively easy to 
analyze, since it tells us what it does, although it may contain provisions for random 
sequences of events or may be written in a way that makes understanding its actions difficult.  

An exploit executable is altogether different, as analysis of its activity can only be fully 
understood when it runs. Exploits that make use of race conditions (unforeseen states of 
running code with undefined outcome) dont make things easier, for they may only be 
reproducible if the test laboratory situation is a very good mirror of the original software 
environment. 

The analysis of the software environment is firmly tied to the artifact analysis, so firmly that 
one cannot be separated from the other. As a result, most of the content of the previous 
section on artifact analysis also applies here. Essentially: 
  Whoever performs the artifact analysis (constituent, incident handling service, or separate 
artifact analysis service) should also undertake the analysis of the software environment. 

  Obtaining and analyzing the artifacts also means obtaining and mirroring the original 
environment as genuinely as possible. Preferably one should use the same operating 
system versions, patch levels, drivers, and configuration files, etc. This requirement 
illustrates how involved and complex artifact analysis can be. What one would really like 
to do is perform the analysis in the original surroundings; but as indicated before, this is 
seldom feasible, since understandably constituents will usually refuse to act as guinea 

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pigs. The risks for them are too great. Some constituents, however, might be prepared or 
able to participate in such analyses (for example, in an academic environment where 
skilled technical staff members are available and easily accessible, isolated test 
equipment may be available, and there is time and interest in the task). 

The analysis of artifacts and the associated software environment may unveil known 
vulnerabilities in specific software (in a specific environment). The victim can then be helped 
with appropriate advice [Garfinkel 1996] and in cases of widespread exploitation, a heads-
up can be sent to constituents and other CSIRTs. On the other hand, the analysis may unveil 
as yet unknown (or at least unpatched) vulnerabilities. This problem should then be 
transferred to a vulnerability handling service. That service might exist within the CSIRT or 
external to the team (e.g., trusted experts, colleagues, or vendor teams). In the ideal case, the 
vulnerability would then be promptly patched and everyone affected would be appropriately 
informed. 

3.4.2.6  Intra-Incident Web-of-Relations Analysis 

Advanced intruders usually weave a whole web of connections over the Internet, using a set 
of their favorite vulnerabilities to gain access to systems, and then using those compromised 
systems as stepping stones to attack yet other systems. Intruders make the web complex to 
evade detection and apprehension. If the center of the web can be identified (such as the 
system compromised as the first one in the chain of intrusions), then it may become possible 
to locate or identify the perpetrator.  

Example: If an intruder uses the telephone system to gain access into the Internet via one 
of the public online services, the telephone company may help with tracking down the 
intruders telephone number used to make the connection. (Usually this means law 
enforcement must be involved.) 

Example: If an intruder is spinning their web from public terminal rooms (at a university, 
for instance, or at an Internet cafe), one needs to catch the offender in the act. When they 
next resume their activity, the location of their machine can usually be tracked through its 
IP number within an organization. If the Internet cafe by itself does not try to detect 
attacks, they will not be able to identify such abuse of their infrastructure. 

One has to take great care when trying to locate an intruder. During the process, the intruder 
and investigator may both make use of the same systems. Often the intruder has the highest 
privileged access on these systems (i.e., UNIX root privileges) and may be alerted to or 
undermine the investigators activities [Stoll 1989, Shimomura 1995]. 

The analysis of the web-of-relations inside an incident is of great importance to help contain 
an incident. The more one understands an intruders operations and relations, the easier it 
becomes to counteract their activity and help prevent others from becoming new victims, and 
finally may even enable capture of the perpetrator. 

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89 

When performing this analysis, one should trace the relations that appear inside log files, and 
keep track of the intruders signature. 

Trace log-file relations 
Log files or parts of log files associated with the intrusion (e.g., telnet logs of the intruders 
activity, sniffer logs) should be carefully examined and every link to other systems should be 
investigated. Usually this means involving constituents and other CSIRTs on a need-to-know 
basis, providing them with only the portions of the logs relevant to them. It is, however, 
advisable to alert your fellow CSIRTs (or at least those teams with whom you have a sound 
relationship) and give them information about the way that the intruder seems to perpetrate 
his attack(s). This will help the other teams to be more proactive and to recognize similar 
activity when it occurs. Ideally, the other teams would be expected to return the favor and 
inform you if the situation were reversed. 

When the search yields new log files with relations, these need to be similarly analyzed. This 
can be quite a time-consuming job. This is especially true in incidents involving Ethernet 
sniffer logs. Such incidents have caused several CSIRTs a tremendous amount of effort 
tracking and notifying all affected sites of possibly compromised systems. 

Keep track of the intruders signature 
Throughout the incident, you (or others involved by you) need to make sure the intruders 
signature is abstracted and compared with the signature as you know it. The signature is the 
way the intruders go about their work, the scripts used, the passwords tried, the programs 
they attempt to break, the vulnerabilities exploited, and the file or subdirectory names they 
invent or use to store their tools. 

Keeping track of this signature will enhance your understanding of the intruder. You may also 
find instances where the signature seems to be totally different. Your intruder might either be 
very creative or this might be the signature of another intruder whose path you have crossed 
by accident. Alternatively the signature could be the result of intruders working together and 
sharing information. By following one intruders trail, you might start finding their 
colleagues trails too. These trails could show both remarkable similarities and clear 
differences. 

3.4.2.7  Analysis of the Texture of Ongoing Incidents 

Not only should all relations within every incident be investigated, but also separate incidents 
should be compared with one another (this adds to understanding the bigger picture 
mentioned earlier in this section). The same two aspects stand out again as main quantities to 
evaluate during any analysis activities: intruders signatures and the web-of-relations. 

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Because the analysis of a seemingly coherent incident may show that another intruders 
tracks are confusing the proceedings, analysis of the texture of incidents may show that 
separately treated incidents may well belong together. The similarities may result from the 
same intruder with the same signature or from a group of intruders apparently working 
together with a similar or almost identical signature and web-of-relations; alternatively, there 
might be completely different, unrelated attacks against the same target. Only through the 
analysis process will such understanding be obtained. 

3.4.3  Tracking Incident Information 

During the life cycle of every incident, it is very important to track information pertaining to 
the incident at varying levels of detail. This facilitates the organization of information and 
effective response to the incident. This recording of information in a logical, organized way 
will also provide a historical record of reported activity and all actions taken to assist in the 
distribution and allocation of incident workload. This record can also provide statistical and 
trend information that may be used within the handling function or by other functions or 
services; for example, management or sponsor reports, customer quality assurance, staff 
performance measurements, etc. 

The level of detail recorded may vary from team to team based on their specific 
requirements, the level of incident handling service provided, and the depth of analysis 
undertaken. For every incident, a good practice is to capture and track at a minimum the 
information detailed in Table 16. 

Depending on individual policies, teams might store online incident information only for a 
short period of time while it might still be needed, such as a few weeks after closing an 
incident or to generate regular statistical information. Usually the information is kept at least 
a little longer, to allow the possibility of an incident reopening. If the tools support the 
reopening of incidents, this is a must. In some cases CSIRTs have reported incidents 
reopening a year (or longer) after the original report! Such cases are mainly due to sites 
failing to regularly review logs for incident activity, but can also be the result of a law 
enforcement case finally reaching a trial date. Depending on the nature of the team and 
services provided, there may be no need to store the whole set of collected incident 
information indefinitely, although it might be helpful for historical purposes. This topic is 
discussed in more detail in Section 3.8, Information Handling. 

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Table 16:  Incident Tracking Information 
Information to be Tracked 
Local CSIRTs unique incident 
tracking number 
Other CSIRTs incident tracking 
numbers 
Keywords or categorizations 

Description 
Unique tracking number supplied by this team. This is used to track all 
information and actions relating to the incident. 
Tracking numbers assigned by other teams involved. This facilitates the 
appropriate coordination of this incident across other teams. 
Information to characterize the incident and help establish relationships 
between different incidents. This information may change during the 
incident life cycle as new information becomes available. 
Names, phone numbers, email addresses and other contact information for 
all parties involved in the incident. It should include details of preferred 
encryption methods and associated keys. 
Legal parameters or policies that affect the way the incident might be 
handled. 
Priority of the incident according to the CSIRTs priority scheme. An 
incidents priority often changes during its life cycle. 
Location of other materials associated with this incident, such as log files or 
hard-copy materials. 
Chronicle of all email and other correspondence (e.g., details of telephone 
conversations, faxes) associated with the incident. 
Current status of the incident. 
List of past, current, and future actions to be taken in respect to this incident. 
Each action should be assigned to a specific team member. These actions, as 
appropriate, might also capture completion dates and other deadlines. 
A team may choose to assign a staff member to coordinate the response to 
this incident. This person might not always be available, which raises its 
own problems, but with one person seeing all information related to the 
incident a better picture can be built. 
Information that might help to measure the quality of the service. References 
to service level agreements that might affect the handling of this incident. 
A free-form description that accommodates other information not covered in 
any other tracking field. 

Contact information 

Policies 

Priority 

Other materials 

Incident history 

Status 
Actions 

Incident coordinator 

Quality assurance parameters 

Textual description 

3.5  Announcement Function 

As previously stated in Section 3.2, Service Functions Overview, the announcement 
function generates information tailored for the constituency in various formats. The purpose 
of announcements varies from disclosing details of ongoing threats and, steps that can be 
taken to protect against those threats, to sanitized trend information on the scope and nature 
of recent attacks reported to the team. For the purposes of this handbook, the scope of this 
function is limited to its direct applicability with the incident handling service. For a CSIRT 
providing a broader range of services, however, publishing announcements can be considered 
as a service in its own right and would likely offer a much broader range of information 
derived from other services, such as vulnerability or artifact analysis. 

Example: Announcements such as CERT Advisories [CERT/CC 1988] provide 
information on preventing threats that are generally discovered as the result of incident 

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reports, vulnerability reporting, and testing based on patches, as well as security updates 
made available by the vendor community. 

Since the formation of the first CSIRT, announcements to teams constituencies have 
generally, in some form, been part of a CSIRTs daily business, whether as a distinct service 
or as part of the incident handling service. As previously mentioned, however, this 
announcement function is optional, as it is not critical to the provision of a basic incident 
handling service. The main objectives for announcements are to disclose information to the 
constituency, to assist them in protecting their systems, or to look for possible signs of attack 
by providing notification of potential, current, or recent threats; and further to suggest 
methods to detect, recover from, or prevent threats. When disclosing information related to a 
specific attack type, care should be taken to ensure that the level of disclosure is sufficient to 
allow recipients to understand the threat and check for it, but not detailed enough to enable 
the information to be used to implement the attack. This is the most challenging task of the 
announcement function. 

A list of announcement types and a discussion of the announcement life cycle follows in 
Sections 3.5.1 through 3.5.3. Other issues that should be considered when making 
announcements to a constituency are covered more generally in Section 3.8.8, Information 
Disclosure. 

3.5.1  Announcement Types 

Announcements can take on many forms, from those providing short-term information 
related to a specific type of ongoing activity to general long-term information for improving 
awareness and system security. Each has its own tradeoffs and benefits. 

Heads-up 
The heads up process usually takes the form of a short message, issued when detailed 
information is unavailable. The purpose is to inform the constituency or other parties of 
something that is likely to be important in the near future. Announcing a heads-up has 
multiple benefits. First, the CSIRT can proactively warn or inform their constituency to a 
potential issue or threat. Second, the recipients may already know something about (or have 
additional information relating to) an issue detailed in the heads-up than the CSIRT. This 
gives the constituency the opportunity to provide feedback to the team. Third, the recipients 
may stumble on information related to the content of the heads-up at some later time. They 
will then be in a better position to recognize the information and its potential importance. 
There is a caveat, however, that information in such documents is likely (and often expected) 
to change, so it might be worth including a disclaimer prominently in the text of the heads 
up to clearly identify when the information is unconfirmed or speculative. 

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Alert 
Alerts are short-term notices about critical developments containing time-sensitive 
information about recent attacks, successful break-ins, or new vulnerabilities. There may 
already be complete information regarding the subject of an alert, but something may have 
changed to require the publication of new information. Examples are documents such as the 
CERT Summary on the named problem [CERT/CC 1998b], a variety of CERT Incident 
Notes and Vulnerability Notes [CERT/CC 1998c, CERT/CC 1998d], and other more recent 
similar alerts, such as the CERT Current Activity page at 
http://www.cert.org/current/current_activity.html. 

Advisory 
Advisories are often one of the most common documents produced by CSIRTs.35 Advisories 
provide mid-term and long-term information about problems and solutions suitable to raise 
awareness and help avoid incidents. They typically contain information about new 
vulnerabilities, but may also contain information about intruder activity. Advisories are often 
well-researched and include substantial technical detail relating to patches and workarounds 
[Cormack 2002].36 Advisories are typically directed at a technical audience such as system 
and network administrators, but sometimes contain additional background information for 
less technical readers. Examples are CERT Advisories [CERT/CC 1988].  

For Your Information 
These are documents that contain mid-term and long-term information, similar to advisories, 
but shorter and less technical to address a wider audience. These might be called briefs, 
bulletins, or newsletters as well. Such documents typically contain information of a tutorial 
or instructive nature that can be used by non-technical personnel with an interest in security. 
This could include management or legal staff and members of the press. An example is CIAC 
C-Notes (originally called CIAC Notes) [CIAC 1994]. 

Guideline 
A guideline is a sequence of steps that lead someone familiar with the basics of his craft 
through a process meant to expand that persons knowledge or even to work direct 
improvements (in system or network security). They can be lengthy documents aimed at 
helping technical staff improve their fundamental understanding of security and their day-to-
day practices [CERT/CC 2000]. Other examples include the Site Security Handbook [RFC 
2196] and CERT Security Improvement Modules [CERT/CC 1997c]. 

Technical Procedure 
Technical procedures are more lengthy than guidelines, with more technical details 
                                                 
35   For example, the CERT Advisory is probably the most common way in which people recognize 

the work done by the CERT/CC. 

36   McMillan, Robert D. Vulnerability/Advisory Processes. 8th Workshop on Computer Security 

Incident Handling, Forum of Incident Response and Security Teams, San Jose, Calif., July 1996. 

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addressing an expert audience and often targeted at a specific problem domain. Examples of 
this are the CERT Tech Tips such as the Problems with The FTP PORT Command 
[CERT/CC 1998e] or the Security Improvement module Security Public Web Servers 
[Kossakowski 2000]. 

3.5.2  A Priori Considerations 

Defining a set of announcement types is just the first step towards a comprehensive 
announcement process. Several other factors need to be considered and addressed before such 
announcements are issued. These factors range from the criteria that trigger an announcement 
to how it will be distributed, and these are discussed in further detail below. 

3.5.2.1  Announcement Triggers 

Criteria need to be in place to determine what will trigger the development and distribution of 
each type of announcement. These criteria could be anything from just another teams 
information to identifying a surge in current attacks being reported to the team. Obviously the 
information required to meet the criteria must be tracked and monitored regularly. Usually 
the information source is either the CSIRT itself, based on the activities reported to the team, 
research done by the team, or the source of some other teams announcement. 

3.5.2.2  Categorization Criteria 

It is useful to derive criteria to help categorize announcement material, that is, help to pick 
the right type of announcement for that material. Criteria based on the source of the material 
are not hard to define; criteria based on content type are much harder. 

Examples: Material that is derived from public mailing lists such as Bugtraq may cause a 
heads-up but certainly not an advisory, unless the content is double-checked and/or 
verified through other investigation (source-based criteria). Likewise, if a CSIRT does 
not generally handle virus issues, a new surge in viruses is not likely to cause an advisory 
or guideline, but it may yield an alert or heads-up (criteria based on content type). 

When categorizing the content of material, the target audience for the announcement must 
also be considered. 

Example: A very technical description of a Sendmail exploitation may well trigger a very 
technically detailed advisory aimed at experienced system administrators, not the general 
user population. A less-detailed technical description of a problem in some popular 
Web browser might better result in a for your information aimed at a much wider 
audience. 

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3.5.2.3  Prioritization 

Several (more or less subjective) factors will affect the perceived importance of each 
individual announcement. Care should be taken to preassign objective priorities to each 
announcement based not only on specific type of announcement but also on its content (i.e., a 
handful of broad topics such as denial-of-service attacks or viruses). CSIRTs need to use the 
right vehicle (e.g., announcement type) to get the appropriate information disseminated to the 
right audience(s). 

Example: Originally the CERT/CC had just one method of announcing information 
publicly to its constituency: the CERT Advisory. This document type was the mechanism 
by which CERT staff disseminated important information that system and network 
administrators should pay attention to. This proved effective for a while; however, 
clearly some issues are more important than others. Having just one publication vehicle 
to disseminate many different types of information can dilute that publication vehicle 
(e.g., everything cannot be the highest priority; true for incidents and also for 
announcements). 

Over time, the CERT/CC developed other notification schemes, such as the CERT 
Summary, CERT Incident Notes, CERT Vulnerability Notes, and CERT Current Activity. 
In this way, the CERT/CC uses the Advisory announcement type for the most important 
issues that CERT staff want the constituency (e.g., system and network administrators) to 
immediately review and address as appropriate to their particular situation. Other 
CERT/CC publication vehicles are referenced in Section 3.5.1. 

3.5.2.4  Clearance of Information in Announcements 

According to the CSIRTs policies and procedures governing the disclosure of information, 
the information intended for use in the announcement must be cleared for disclosure at the 
appropriate level (whether for public or restricted distribution). Some general clearance rules 
should be set beforehand to help this process run smoothly in practice. 

Examples: An obvious clearance rule for a public announcement would be that it may 
never contain details about individuals or individual sites. Another such rule is that if the 
information going out is based on or simply a redistribution of materials provided by 
other teams, appropriate permission must be obtained from those teams, and the 
appropriate attributions included. 

3.5.2.5  Distribution Channels 

Depending on the announcement type, different issues need to be considered when choosing 
appropriate distribution channels: 
 
 

audience (constituency) addressed: Is the channel adequate to reach this audience? 

sensitivity of information: Is the distribution channel safe enough? 

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speed: Is the channel fast enough? 

cost: Is the expected result in producing and distributing the announcement worth the 
money (e.g., time, effort, materials, value)? 

Other issues relating to distribution channels include the manner in which the information 
will be distributed or disseminated. This is discussed in Section 3.5.3.5, Distribution. 
Whatever mechanisms are considered appropriate, they should be set up and tested in 
advance and then advertised to the constituency. 

3.5.3  Announcement Life Cycle 

Having decided on appropriate announcement styles and initial criteria, the next step is to 
define processes and procedures to handle the actual generation of announcements (type, 
form, style, etc.). In general, the five phases described in this section can be recognized in the 
life cycle of an announcement, ranging from the first evidence for its need to its ultimate 
distribution. 

3.5.3.1  Initiation 

When possible announcement material is identified (e.g., during incident analysis or through 
observing likely sources such as mailing lists), a determination must be made as to whether 
the material meets the general criteria referenced in Section 3.5.2, A Priori Considerations, 
or is otherwise important enough to be announced. If so, the type of announcement, the 
content type, and the intended audience will have to be made explicit, and it is helpful if an 
internal tracking number is allocated. This facilitates the tracking/recording of the 
development of the announcement.  

The priority or importance of the topic, announcement type, content type, and audience 
determine the following important parameters: 
 
 
  distribution channel to be used 

style and detail in which the announcement will be written 

information clearance measures to be taken 

In addition, other issues that need consideration or decisions at this point include the 
proposed time schedule, internal resources needed, responsibility for the task, and other 
aspects such as collaboration with other parties (to provide content or improve the quality of 
the announcement, or to synchronize publication of announcements with other collaborators). 

3.5.3.2  Internal Prioritization of the Announcement 

This phase may be revisited regularly for all announcements currently under development. It 
is possible for some teams to have a number of concurrent efforts underway for 

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announcements (in various stages of development): yet unissued announcements are 
prioritized based on the predefined criteria and other relevant criteria determined at the time 
the content begins to be developed. Certain types of announcements (by their very nature) 
might have the highest priority if they are time critical, and can supercede other important 
announcements already in the queue. Others that simply provide general statistical 
information may be of the lowest priority and deferred to a later date for announcement. 
Relative priorities might not be immediately obvious when two comparably important 
announcements are competing for resources. In such cases it is best to prioritize based on the 
severity of the issue, e.g., threats addressed and/or the size of the constituencies involved. 

3.5.3.3  Development 

This phase is composed of the technical description, editing, and overall writing of the 
announcement. Most teams generate a standard template for each type of announcement that 
indicates the appropriate layout and content of the material. This boilerplate can greatly 
facilitate the development of the material, and it also helps to maintain a consistent look 
 to the announcement form and so sets the constituencys expectations for what the content 
will cover. Drafts of the announcement may then be provided for internal and limited external 
review to obtain detailed comments from experts not directly responsible for developing the 
announcement. When providing other parties with this information, any restrictions to use 
must be made apparent. 

Example: An early draft announcement may be sent out to all FIRST teams to seek their 
review and comment, but is labeled not for further distribution. To further protect it 
against attacks or possible disclosure, drafts and comments should be encrypted and 
digitally signed when distributed for such review and comment. 

3.5.3.4  Final Preparation 

Prior to final dissemination, some technical issues still need to be addressed, such as 
generating cryptographic checksums of the announcement itself or items that it references. 
However, most of the issues that remain at this stage are non-technical. They are usually 
concerned with the overall presentation and content (i.e., dates, headers, footers, 
acknowledgments, and disclaimers). Before releasing the announcement, the team must make 
sure that all the references it contains are valid (i.e., URLs and patch files are correct and 
accessible).  

Another matter for consideration is whether or not it is appropriate to offer an advance 
distribution of the announcement to a limited audience, such as fellow CSIRTs or your teams 
media contact. This gives such parties the opportunity to prepare for any responses they may 
receive. For a fellow CSIRT, this might mean preparation of an announcement of their own, 
e.g., if they need to translate the information to another language or will simply wrap your 
announcement with their own boilerplate. In such cases it is appropriate to retain distribution 

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restrictions on the announcement until the moment of ultimate disclosure, in case there are 
any last-moment changes required. 

Example: Some CSIRTs send out encrypted final drafts of their advisories to all FIRST 
teams with the proviso that those teams can use the information to prepare their own 
announcements, but they are not free to further distribute the information until a final 
public distribution version has been made available. As a result, any possible conflicts of 
interest can be minimized. If one of the reviewers disclosed the information prior to the 
final public distribution date, this would damage the whole process, as the information 
would be leaked while others believed that it was still confidential. 

Team members providing triage, feedback, or other incident handling functions need to be 
prepared to copy or address any possible responses to an announcement from the 
constituency, media, or other parties. Advance briefings on all announcements should be 
provided for these team members. 

Finally, every outgoing announcement should be allocated an external tracking number, 
which usually is serially allocated per announcement type. Then the announcement should 
also be digitally signed to protect against tampering. 

Example: Every CERT Summary distributed by the CERT/CC has a number of the form 
CS-YYYY-XX (where YYYY is the year in which the summary was issued and XX the 
number sequentially allocated from 01 for each Summary issued in that year). 
Authenticity and integrity is provided by a digital signature generated with PGP (or 
GPG). This is also true for other CERT documents (e.g., CERT Advisories, Incident 
Notes, and Vulnerabilities Notes). 

3.5.3.5  Distribution 

This activity is related to the effort involved to distribute or disseminate the final 
announcement via the distribution mechanisms that the team advertises for announcements of 
that type. This might include placing the announcement on appropriate information servers 
such as the teams FTP or Web server, or distributing it via other mechanisms such as mailing 
lists, automated fax distribution, or news mechanisms. 

Example: The CERT/CC issues many of its announcements (such as CERT Advisories 
and CERT Summaries) to a mailing list known as the cert-advisory mailing list, and to 
the USENET newsgroup comp.security.announce. The latter is moderated by CERT staff 
and intended solely for the use of CERT announcements. In addition, the CERT/CC 
archives all announcements (including those not directly disclosed via the mailing list 
and newsgroup) on its Web server.37 

                                                 
37   http://www.cert.org/ 

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3.6  Feedback Function 

Providing support for recovering from and dealing with incidents is the major objective of 
most CSIRTs. Being effective in this role will lead to other requests and issues being directed 
at the team that are not necessarily specific to the incident handling activity (or perhaps 
requests that are not even part of the CSIRT mission or services provided to the 
constituency). Unfortunately, simply ignoring such requests and issues (even if they are 
beyond the scope of your CSIRTs roles and responsibilities) can affect the teams reputation 
and the attitude of the constituency toward the team. Hence, it is in the interest of all CSIRTs 
to provide some level of appropriate feedback at some minimal level to such requests.  

On the other hand, from a knowledge management perspective, the type of incoming requests 
received by the CSIRT can provide some insight into the current needs of the constituency 
and other interest in the team. As a result, providing feedback to such requests can help to 
deliver a better service and at the same time clarify the expectations of the constituency 
instead of ignoring obvious problems and misconceptions. The CSIRT should strive to 
answer requests, no matter what the request (even if it is a reply saying We cannot respond 
to this request, it is beyond the services we provide, or pointing to other information 
resources). 

Example: If a team does not reply to questions directed at it, the requester may think of 
the team as unhelpful or unable to help. Other requesters might think the team is arrogant 
or worse (mismanaged, uninformed, etc.). To avoid this perception, the team should at 
least provide a statement of the purpose of the team and why no further feedback is 
provided. Keep in mind that some of these requests can be the result of investigative 
journalism (seeking to elicit information that may not be public), and can come in many 
shapes and sizes. 

Incoming requests commonly fall into one of four categories: 

1.  general computer security requests 

Such requests commonly seek information on avoiding incidents through proactive 
security measures or how to interact with the CSIRT if an incident should occur. As 
CSIRTs regularly deal with incidents, they have the knowledge to provide this type of 
information. Therefore it seems natural for people to direct questions of this type to the 
team. Whenever possible, a team should make use of such opportunities to proactively 
help the constituency raise awareness, avoid (or limit) incidents, and improve the overall 
security. 

2.  media requests 

These are requests from members of the media who may be seeking input for a story 
relating to a general security article, announcement, or specific incident. Whenever 
possible, the CSIRT should be prepared to appropriately handle such requests from the 
media, while ensuring that the teams information disclosure policy is not violated. 

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3.  other requests and issues 

There is a whole range of other requests and issues that constituents may submit or that a 
team might wish to provide feedback on. These include requests for the team to provide 
a speaker at a conference or a request for permission to make use of copyrighted 
material available from the team. Handling such requests may help promote awareness 
of the team and, when feasible and appropriate, should not be ignored. Sending out the 
CSIRTs annual reports can be placed in this general category, even though that is a 
matter of disseminating information proactively rather than responding to a request. 

4.  out-of-scope requests 

These requests have nothing to do with the services provided by the CSIRT, but even so, 
as mentioned above, a simple acknowledgment with a reference to some Frequently 
Asked Questions (FAQ) or policy statement on how to deal with out-of-scope requests is 
more useful than just ignoring the request. 

Example: Typical real-life examples that are obviously out-of-scope are: How do I 
connect to the Internet? Do you have the postal address for my old friend in Hamburg, 
Germany? I need a pen pal. Others may also be beyond the scope of the offered services 
of the CSIRT, such as, Will you perform penetration tests on my network? Which 
operating system version|application|software tool should I use? 

3.6.1.1  Life Cycle 

Teams may choose to track each different type of request with different types of tracking 
numbers. Or they may track all requests with a single type of tracking number and document 
the different type of request made or the nature of the response given for each request. 
Requests have a life cycle similar to those of incidents. However, it is uncommon for these 
requests to remain open for very long after the initial response from the team, although some 
may result in further dialogue. 

3.6.1.2  FAQ and Other Default Feedback 

Responses to requests can be handled individually, but this is often time consuming and the 
CSIRT may not be able to assign dedicated resources to this work. Most teams choose to 
develop previously prepared documents such as a team FAQ document, as mentioned earlier. 
Such a document answers some general questions about the team, gives details of the 
incident handling service provided by the team, and tells how to access documents that 
address specific needs tailored for the constituency. Once such documents are available, most 
requests can be handled by providing pointers to or copies of the appropriate document(s). 
Even in the case of out-of-scope requests, the teams FAQ might be an appropriate response 
if it outlines the services provided by the team and states that all other requests are 
inappropriate. On the other hand, a simple standard reply could be developed that politely 
indicates to the requester that the CSIRT does not have (and so cannot provide) the 
information being sought. 

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Example: A newly formed CSIRT might initially choose to track and respond to requests 
from their constituency to identify common types of requests received and then develop 
their FAQ to quickly handle such general (or similar) requests in the future. Over time, 
such an FAQ can be updated and expanded, placed on the teams Web site, and/or 
provided in response to future requests. The CSIRT Development Teams FAQ evolved in 
this way [CERT/CC 2002b]. 

For media requests, depending on its policies, a team might use an existing organizational 
media office or interact with the media through a team member or associate experienced in 
interacting with the media. Once the team has established a policy for where to direct media 
contact requests, all media requests should be handled according to that policy, and no 
additional support should be provided to the media through the feedback function. Depending 
on the teams policy, it might be appropriate to provide the media with publicly available 
information about the team, such as the teams FAQ. 

3.6.1.3  Organization of Feedback Function 

If standard responses are available, technical staff without detailed technical knowledge or a 
direct Web interface can be used to provide feedback to common enquiries within this 
function. Other alternatives might be to point the requester to other sources, such as online 
archives of technical guidelines made available by other teams, or to other technical experts.  

An internal FAQ (or other guidance) for the team members that describes the procedures 
related to handling the various types of requests is also very beneficial, ensuring and enabling 
a consistent reaction to all requests. Such a document should also detail how to prioritize 
requests. For instance, requests from sponsors might obtain the highest priority, followed by 
requests from constituents. Or a team might choose to prioritize on the type of request rather 
than the requester. This internal FAQ can also be a learning tool for new CSIRT staff 
members. 

3.7 

Interactions 

Throughout the incident life cycle, most of the activities of a CSIRT involve interactions with 
other parties. Due to the importance and implications of such interactions, great care must be 
taken to establish contacts with the right parties (see Section 3.7.1, Points of Contact). 
For the majority of interactions (i.e., communications) it is equally important to ensure 
authenticity (Section 3.7.2, Authentication) and preserve confidentiality (Section 3.7.3, 
Secure Communication). This section concludes with an outline of the items to consider 
concerning particularly important interactions such as those with constituents, other teams, 
and law enforcement (Section 3.7.4, Special Considerations). The examples below 
illustrate effects that can have a negative impact on the site and the CSIRT. 

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Example: Say that an incident is in progress. Someone calls a CSIRT and claims to be an 
administrator at site A. The CSIRT provides technical details of the incident and 
appropriate technical solutions. The next morning there is a headline revealing the 
identity of victim site A, together with a detailed report about the incident. It turned out 
that a journalist heard rumors about the incident and tricked the team into giving out the 
information. 

Example: Unencrypted email messages between a CSIRT and site A are monitored and 
copied by a third party during storage on an Internet mail host. Later the email is 
distributed to Internet newsgroups to a large number of readers. 

On the other hand, effective communications can also have a very positive impact, as in the 
following example:  

Example: In February 2002, the CERT/CC published CERT Advisory CA-2002-03 on 
Multiple Vulnerabilities in Many Implementations of the Simple Network Management 
Protocol (SNMP). Throughout the development and preparation of this advisory, a large 
number of new vendor contacts had to be established to ensure the right contacts were 
identified and contacted. This advisory was, by far, one of the most complex advisories 
published to date; involving coordination, secure communications, and interactions with 
a very large number of vendors (over 100) and other experts. Updates to the vendor 
information continued to be made almost a year later as new information was obtained 
from the vendor community.38 

3.7.1  Points of Contact 

During the course of any incident, contacts are established as necessary. To establish the 
right or appropriate contacts; however, is an art in itself. It is important to pass information 
on, but more important is finding the person best suited to handle and receive the information 
and/or the person authorized to take actions or make any necessary decisions. Therefore, 
establishing and maintaining good contacts must be an ongoing effort of the CSIRT, with the 
intention of building a web-of-trust to meet the needs of the incident handling process. 

For our purposes, contacts can be considered broadly in two categories: incident-related and 
non-incident related contacts. These are discussed in more detail below. 

3.7.1.1  Incident-Related Contacts 

These are the contacts that a CSIRT will need when handling a specific incident. They can 
include contacts within and external to an organization experiencing an incident. Examples of 
such contacts are 

                                                 
38   The printed version of this advisory from the CERT Web site is over 50 pages long.   

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sponsors 

security officer 

technical (system and network) administrators 

  upper management (managers, department/division/bureau heads) 
 
  other departments 
 
 
 
 
 
risk management group 
  network operation center 
  network information center 

legal counsel or legal compliance department 

internal audit department 

In large organizations there may be a predetermined initial point of contact (POC) that the 
CSIRT notifies concerning an incident report occurring at that particular site. However, it 
may be essential for the CSIRT to then be placed in contact with a specific department or 
appropriate individual(s) who can respond to the activity. Without direct contact to the 
appropriate technical or management level staff, the CSIRT may waste precious time and 
resources. 

3.7.1.2  Non-Incident-Related Contacts 

(constituency) site security contacts 

Non-incident-related contacts can be used to provide background information for (or about) 
the team, help it to fulfill its service, potentially support the teams operation, or be used for 
obtaining input from domain experts. The following list provides example categories for 
some of these non-incident-related contacts that could be considered when generating a 
contact database. Examples are 
 
  other constituency site contacts (like management, physical security, human resources) 
 
 
  other CSIRTs 
 
  vendors 
 
experts 
  media 

law enforcement, legal counsel 

sites external to constituency 

Internet service providers 

Constituent Site Contacts 
As previously mentioned, there is a very good reason for maintaining different kinds of 

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contacts within one organization: the possible need for escalation. While it is usually 
acceptable to handle an incident in cooperation with one single department, upper 
management should be involved when it is obvious that an incident has consequences that 
require management authority or oversight or an incident that crosses multiple 
divisions/departments. 

3.7.1.3  Finding Contacts 

Finding the right contacts for organizations is not always a simple task. For non-critical 
contacts, one can use publicly available resources, like telephone directories or similar 
services available on CD-ROM or through a search on the Internet. 

Whenever a critical decision must be based on a contact, using the wrong contact may result 
in leakage or disclosure of critical information to inappropriate parties or (usually worse) to 
outsiders. It also demonstrates a lack of control and attention to detail within the CSIRT, 
which is bad for its reputation. 

To keep the confidence of the constituency, great care must be taken to identify (vet) and use 
the correct contacts. If publicly available contact information can be forged, manipulated, or 
corrupted (a potentially very real threat, with the risk varying from printed media, CDs, to 
network directory servers), it should be verified before use. Better still and always preferable 
is to obtain the contact information directly from the source, from the contacts themselves or 
their management (or designated representatives). 

3.7.1.4  Maintaining Contacts 

This is a seemingly simple task, but in reality, maintaining contact information can be a more 
daunting challenge than finding it. Contact information becomes (partially) obsolete when 
people leave an organization, are promoted, are reassigned to other types of work, or just 
relocate to another desk/office/building with another telephone number. One can ask contacts 
(e.g., constituent sites) to pass on information relating to these kinds of changes; however, the 
reality is that this rarely happens. For non-critical contacts, it is best just to accept some 
potential for outdated or incorrect information in the database and correct the information 
when it becomes known. For critical contacts, this is less appropriate, and regular check-ups 
on a periodic basis (quarterly, semi-annually, annually, when contracts change, etc.) can help 
address this problem, in addition to asking the contacts to provide changes and updated 
information. 

Example: CERT-NL demands of each of its constituents that management appoints a site 
security contact (SSC) and relates the contact information (and any changes pertaining 
to it) to CERT-NL. For practical reasons, it is even advised that the constituents create 
generic email addresses of the form ssc@somesite.nl for their site security contacts. 
The local administrator is then responsible for maintaining the email address. This makes 

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the relay of information possible without prior involvement of CERT-NL. Furthermore, 
CERT-NL advises its constituents to create security entry points, with an email address 
of the form sep@somesite.nl. This security entry point is like a local CSIRT intended 
to handle incidents and other security issues in real-time, separate from the site security 
contact, who may be on holiday or ill. 

Example: Other CSIRTs advocate that at the least the RFC-defined standard email 
addresses for postmaster and security for each domain are provided. 

3.7.2  Authentication 

An important aspect when interacting with others is authenticity. This term usually applies to 
ensuring that someone is really the person she/he claims to be. By using technical 
communication facilities, it is inherently more difficult to check the authenticity of a caller or 
called person. Therefore great care must be taken. Information that must be protected should 
be revealed only after the caller or called person has been authenticated and the other party is 
authorized to access the information. As this information might become important later, each 
contact and its origin must be logged. 

To know that a person is the person that she/he claims to be is important, but only half the 
story. Appropriateness and authority are the other half. In addition to checking for 
authenticity, its essential to determine whether the person is the correct or appropriate 
individual with which to interact in the organization. By correct, we mean that the person is 
authorized to receive, accept, or act on the information.  

Examples: During an incident a call is placed to the security manager of organization 
XYZ. Because the manager is not available, the secretary takes the call. The secretarys 
identity might be authenticated; however, it still might not be appropriate to discuss with 
or disclose to the person details that are intended for the manager. It might be more 
appropriate to leave a message for the manager to return the call as soon as possible. 

Alternatively, a senior manager of XYZ might telephone the CSIRT and demand all kinds 
of action to be taken with regard to the same incident. If this person was not the teams 
registered point of contact for such issues, the CSIRT would need to refer him or her 
back to the registered point of contact of that organization to make the demands (if 
appropriate) through the appropriate chain of command. 

Without such procedures for authentication in place, teams and their constituencies are 
potentially susceptible to social engineering attacks (discussed below). 

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3.7.2.1  Social Engineering 

Social engineering is a phrase commonly used in the CSIRT community to refer to a situation 
where someone presents a fake identity to trick another person into doing something that they 
would not normally do if the real identity were known [Gordon 1995, Greening 1996]. A 
classic example of social engineering (like the example above) is of someone pretending to 
be a high-ranking official and telephoning the guard, telling him to open the gates or else. 
Amazingly enough there is evidence that brute-force psychological attacks similar to this are 
still successful today. Two examples of this type of attack are relatively well known: 
  unsolicited media calls: 

When a media representative thinks that an incident is going on, (s)he may try to get 
insider information. By not revealing her/his identity or explicitly pretending to be just 
another victim, a team member might reveal information in an effort to help a victim to 
recover. 

 

intruder calls: 
Social engineering is a well-known technique for intruders. If the intruder thinks the 
CSIRT may be monitoring their activity (such as an intrusion), they might call the team 
in an attempt to find out if their activity has already been detected. They might pretend to 
be a contact from the site in order to elicit information about the activity, much like the 
media example given above. 

Other social engineering approaches can be seen in the well-known ploys to entice people 
into extracting an attachment or visiting a URL. These may contain nasty side-effects. 

Example: With regard to email, unsolicited items are sent to unsuspecting recipients. 
These may contain a return address, a provocative envelope, or something else that 
encourages its receiver to open it. Malicious email often contains a return address of 
someone we know and often has a provocative Subject line. The unwary recipient may 
not exercise due care in handling that message.39 

3.7.2.2  Technical Possibilities and Limitations 

Modern telecommunication facilities like ISDN provide the caller ID feature. The 
telephone number of the calling site is signaled to the called site, and if the telephone has a 
display, this number can be shown to the person receiving the call (however, there are also 
features to block caller ID). 

Depending on the technical communication facilities, support can be available to prove or 
verify authenticity. One of the most well-known authentication methods in relation to todays 

                                                 
39   An easy-to-read article on Home Computer Security provides additional information about 

social engineering attacks (as well as other computer security issues) that might be helpful to your 
constituency. It is available from the CERT web site at 
http://www.cert.org/homeusers/HomeComputerSecurity/#3. 

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networks are digital signatures, such as those used in the secure mail systems PGP and 
S/MIME. 

Example: To authenticate the origin of all outgoing email, a digital signature produced 
with PGP authenticates each email message issued from DFN-CERT.40 Every recipient 
can check (verify and authenticate) this signature with PGP. This check relies on the 
authenticity of the public key the DFN-CERT member used for the digital signature. 
Therefore, it is the responsibility of the recipient to check the signatures using the 
published PGP public fingerprint of all the DFN-CERT team members. 

Other tools like S/MIME depend on a hierarchical key certification process, where 
certification authorities (CAs) or trusted third parties (TTPs) check the authenticity of a 
user and the relationship between the user and their public key. If they are able to verify 
this information, they will certify the keys authenticity. 

It is important to note that digital signatures can also provide a high level of authenticity and 
protection against disclosure or other attacks by using associated encryption capabilities (e.g., 
both PGP and S/MIME are capable of this). It is important to understand the limitations of 
the mechanisms used and to use each mechanism within these limits. When there are inherent 
problems or tradeoffs, organizational approaches can help provide the necessary security. 

Example: CERT-NL uses a new team-key each year. As the team-key is used for day-to-
day operation, it is stored on systems that, more or less, have a direct connection to the 
Internet. There is, however, a CERT-NL master certification key that is kept off-line (is 
never used on an Internet-connected host) and whose use is controlled by a strict 
procedure. Every time a new CERT-NL team-key is generated, it is signed using the 
master certification key. All the keys of the CERT-NL staff members are also signed 
using the master key. This overall system neatly blends practical demands and security. 
Constituents must verify that the staff keys are properly signed by the master certification 
key and can then safely use the staff keys without checking the fingerprint of each staff 
member individually to verify the key. To bootstrap the process, all constituents must 
obtain and verify the public master certification key. 

3.7.2.3  Databases 

Another area where tools are involved is the use of information databases, particularly those 
containing contact information. As internal databases form an integral and important part of 
the interaction process and CSIRT communications infrastructure, they should be very 
carefully protected. If an attacker could manipulate the database, they could compromise the 
data, and seemingly authenticated data could be entered and the team members would trust it. 

                                                 
40   Many other CSIRTs also PGP-sign messages, as well as other documents they produce or 

disseminate. 

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The same problem exists when using public information sources. Here the possibilities for 
manipulation are greater, and hence the invested trust in such information by the CSIRTs is 
limited. 

Example: The DNS system and Whois databases (two widely used directory services on 
the Internet) are often used for contacting victim sites when no better point-of-contact 
information is available. As it is possible to masquerade as a DNS server for another 
system, every public information server must be considered as not trusted. Besides 
questioning the authenticity of the information available, one may well also question the 
integrity of the data: for example, Whois information is often outdated or contains errors. 
In the worst case such flaws may lead to passing information on to the wrong person. 

Example: In Europe a directory of European CSIRTs is maintained by the Trusted 
Introducer service.41 This service maintains related records of European CSIRTs in the 
Whois database (IRT objects). This allows the lookup of the responsible CSIRT based on 
IP addresses. 

3.7.2.4  Anonymous Information 

The final area is how a team should deal with anonymous calls or calls that cannot be 
authenticated at all. No sensitive or substantial information should be passed to any 
anonymous callers. But when they provide new information, a team must decide if such 
information is useable and if (and how) such information should be handled. It may not be 
possible to verify the information provided, so it should be tagged as such and its anonymous 
origin must be tagged too. One of the best reasons for considering the use of anonymous 
information is that it makes no difference, for example, whether a warning comes from an 
anonymous caller or noteither way, to be safe, you will check whether the warning is valid. 

3.7.3  Secure Communication 

Authenticating the origin of important data is only part of its safe handling. It is also 
important to adopt security mechanisms suitable to protect the information during its 
transmission across networks. This does not only apply to computer and telephone and other 
telecommunication networks (including remote systems and access), but also information 
transmitted via more traditional means, such as post or couriers, which are also vulnerable to 
attack (or loss). 

In the same way that cryptographic mechanisms can help to ensure authenticity, they can 
ensure confidentiality. Efficient encryption mechanisms are available, although for various 
reasons, specific mechanisms are not universally allowed or are not exportable to other 
countries (government regulations). 
                                                 
41  For more information on the Trusted Introducer service, see 

http://www.ti.terena.nl/teams/index.html#DIR. 

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Wherever cryptographic mechanisms are used, key management is a major issue to address, 
by means of a policy and operational procedures. 

Example: FIRST uses PGP to protect email communications. As it is very difficult to use 
public key encryption with a large number of parties (in January 2003 FIRST had almost 
130 member teams) conventional (symmetric) encryption is used. All FIRST members 
share the knowledge of the same pass phrase, which is changed regularly. In addition, 
digital signatures can also be used to provide authenticity, enabling other teams to check 
the origin of a message. The procedures for use and maintenance of the keys are 
distributed among FIRST members [FIRST 1998]. 

In the case of telecommunication networks, additional black boxes can be applied, since 
confidentiality is not usually a default feature of telecommunication services. Such 
encrypting devices are available in the open marketplace, although the protection provided 
might depend on the implementation and other factors like export restrictions, which limit the 
availability of products all over the globe. 

Example: Some teams use Secure Telecommunication Unit (STU III) or SECURE 
TERMINAL EQUIPMENT (STE) devices, which can protect telecommunications. Such 
devices are controlled equipment that have special handling/reporting procedures and 
requirements for their usage and are limited to certain usage communities (the U.S. and 
Canada, for example). 

Example: Other countries have developed encryption technologies for GSM cellular 
phones or ISDN connections. Usually the application of such technologies will only work 
with communication partners that share the same technologies as well as having 
exchanged the cryptographic keys needed. 

3.7.4  Special Considerations 

The following text will present interaction considerations specific to given environments. The 
objective is to explain the practical considerations for interactions that have already been 
introduced. The parties involved in interactions are not described in detail, but the important 
issues are explained through examples. 

When conducting interactions, one of the first issues a team should address in its policies and 
procedures is the level of service it is willing or able to provide to different parties. This 
statement might include details like response times or might describe specific forms for 
exchanging information. By doing this, available resources are considered and devoted to 
particular tasks and priorities. 

As each teams situation will differ, the examples below, where possible, indicate both 
beneficial approaches to take and pitfalls to avoid. Although the examples provided include a 

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wide range of possible partners, others might certainly exist. But we believe weve covered 
the most important interactions to consider. Any others that you may identify can likely be 
treated similarly to one of the categories below or will be similar to that for the media (i.e., 
open, public, and unknown). 

3.7.4.1  Constituency Sites 

The CSIRTs primary objective is to help its constituency. Most of the issues to consider have 
already been covered in earlier sections of this handbook. For interactions one additional 
consideration to be discussed is the need for different kinds of contacts even within a single 
site. Of course, if the same person at the site fulfills multiple roles, a site may still only have a 
single contact. 

Since the escalation process in dealing with incidents will need decisions (like the decision to 
report to law enforcement), contacts for each phase of escalation are necessary. 

Example: While the technical details of an incident are passed on to an administrator 
responsible for the daily operation of the network connection, some information must 
also be directed to management. If, for example, a site reporting a new incident already 
informed law enforcement, other sites need to know this information to consider their 
own decision in the light of this fact. On the other hand, this information might not 
become available to the CSIRT, and can therefore not be passed on to others. 

When defining policies and procedures, the CSIRT must prevent a single site or constituent 
from consuming all of the teams available resources unless the team considers the activity to 
be of such importance that it should take precedence over all other activities. During periods 
of limited staff resources (e.g., vacations or conferences), prioritization will become even 
more important to distribute the activities among the available staff.  

Documented and publicly available policies will allow the sites and constituents to understand 
limitations and restrictions, but even so steps should be taken to alert the constituency to these 
times. For instance, a holiday message might be distributed that provides information for high 
priority reporting procedures. This appropriately sets the expectations of the constituency, who 
will be more patient with the CSIRT than they may otherwise be without such measures. 

Depending on the size of the constituency and the service provided, pre-registration may be a 
possible option. Clearly pre-registration of a constituency is only a possibility if the 
constituency size is relatively small (in the hundreds) and is fairly stable. It might also be 
possible if the relationship between the constituency and the CSIRT is on a contractual basis, 
such as with a commercial fee-for-service team or network service provider, where it is easy 
to add the pre-registration criteria as a supplement to an existing contract. During the pre-

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registration, issues such as information disclosure restrictions, trusted points of contact, and 
preferred method of secure communications must be addressed. 

3.7.4.2  CSIRTs 

Incidents that require no external interactions with other parties are rare in todays 
unbounded networked environment; they arise only if an incident is local without any 
external relations or side effects. Even then, external interactions may become necessary, 
such as when law enforcement is involved. 

Besides direct contacts at constituency sites, the most important cooperation partners for 
CSIRTs are fellow teams. While handling an incident, direct help and information exchange 
are most important, and there is potential for teams to provide mutual support. This is 
particularly true if the teams have been in the CSIRT business for a long time or have 
particular technical expertise. Other examples of support might be provided in one of the 
forms described in Table 17.  

By exchanging information, cooperating teams usually benefit, making it easier for them to 
either fulfill their duties or provide a better service. But sharing information in the first place 
is not as easy as one might think. When considering the issues outlined in Table 18 it 
becomes clear that the extent to which teams are able or willing to exchange information and 
to cooperate on confidential issues depends on any existing trusted relationship they may 
have with each other. The existence of a formal (written) agreement between two teams 
might make it even easier for the teams to exchange information, assuming a clear 
understanding of all the issues described above already exists. 

If two teams want to initiate a cooperative relationship, they will first need to establish the 
necessary foundation of trust. Building such trust is not an easy task and will require time. 
One of the most important steps towards such a relationship is getting to know each other. 
The teams should exchange visits and try to understand each others goals, objectives, 
procedures, and policies as much as possible. This will help the teams to make a realistic 
assessment of whether a deeper relationship is achievable and beneficial. The teams might 
want to start by collaborating on a small project with minimal risk rather than starting on a 
larger, more complex and risky task. 

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Table 17:  Possible Inter-Team Support Types 
Support Type 
Education/Training 

Description 
This might range from issues like Forming a new CSIRT to technical tutorials to 
understand the nature of incidents. 

Out-of-Hours Coverage  While one CSIRT may only provide service during business hours, another fellow 

Technical Expertise 
Cooperative Work 

Other Opinions 

Point of Contact to Other 
Teams or Experts 

CSIRT may take calls during other hours as part of a collaboration agreement. This is 
particularly relevant if a team operates under the indirect control of a coordination 
center. 
To address technical questions and share this knowledge with other teams. 
To address problems that are too difficult to solve with the resources of a single 
team, two or more teams might come together and collaborate to seek the solution to 
such a problem. This handbook is a good example of this kind of cooperation. 
While working on the solution to a particular problem, the members of the team 
involved may be too close to the problem to view it objectively. To avoid the 
negative impact that might arise in these instances, another team might be asked to 
review and provide an opinion on the proposed solution before it is publicly 
distributed. Existing CSIRTs have a long history of exchanging draft advisories and 
often incorporate many suggestions before the final advisory is released. 
Since a team might need a trusted contact for a specific site or network, they can ask 
other teams whether they have an established contact or if they know somebody else 
to ask. This also holds true for contacts to technical experts and vendors. 

Table 18:  Considerations for Information Sharing 
Issue 
Confidentiality/Secrecy 

Description 
Since the information might also be valuable to other parties, its confidentiality must 
be maintained. This is true for transfer, storage, and actual use. The mere reaction of a 
team member might be enough to reveal at least some part of the information, for 
example the existence of a new bug or security hole or the existence of some other 
incident. 
While the information belongs to one team, it must be clear to other teams that to 
obtain access to the information they must adhere to any restrictions that the original 
team places on the information and conform to what the original team considers as 
appropriate use. Most of the time the official signing of a non-disclosure agreement 
is necessary to obtain such access. Part of a non-disclosure agreement will list the 
rights and duties by which appropriate use is established. 
Since the information may be distributed to the public at some future point in time, 
disclosure restrictions should be stated up front. Some teams put time constraints on 
information. While it is forbidden to disclose the information by any means before the 
time limit, it is perfectly acceptable to incorporate this information in an advisory to be 
disclosed after the time limit. Setting a timeline is not easy in an international 
environment. Differences in time zones mean system administrators in one area of the 
world can be finishing work, or already at home, while others are just starting their 
working day. 
Since the information was collected, analyzed, and made available by other teams, the 
team using it should consider a fair and proper acknowledgment of the original source. 

Appropriate Use 

Disclosure 

Proper 
Acknowledgments 

Just as there are teams that you know from previous interactions, there are also teams that 
you have heard about but are less familiar with. Since you have no knowledge whether the 
team is suitably qualified or even genuine, it can be a difficult decision to pass information on 
to them. If you have some initial knowledge about the team, the decision may be easier to 
make. One way to obtain such information is to ask other teams that you have a good 

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relationship with what their experiences may have been with those team(s) that you are less 
familiar with. It would be so much easier to rely on a mechanism to identify trusted teams, 
but as yet no such mechanism exists. 

Well continue by discussing other issues involved in inter-team cooperation. These issues are 
more closely related to the CSIRTs operational procedures. 

Mandatory Information 
The issue of dealing with incoming information was described previously. There is critical 
information that a team must have before it can process a report. If this information is not 
supplied in the initial report, a delay will be incurred until the team obtains the information. 
The delay can be significant in some cases, such as if the report was sent just before a 
weekend or if extreme time zone differences are involved. A team can attempt to ensure that 
another team reports the mandatory information through the use of an inter-team reporting 
form, but such a process will need to be developed before that type of situation arises. 

For example, a team may choose to share or report information at a peer-to-peer level (CSIRT 
to CSIRT); they may choose to report up to a high-level coordinating team (e.g., a 
Government or country-level CSIRT), or the team may be mandated (through a regulation) to 
report because of the organizational structure (e.g., some teams in the U.S. are required to 
report up the command chain within a specified time). Not all inter-team relationships are 
at the peer-to-peer level. Some teams elect to participate in a voluntary hierarchy as the 
situation may dictate. 

Example: Two or three CSIRTs may share the roles in analyzing a piece of malicious 
code or new vulnerability, with one team collecting the analysis from each and 
coordinating the overall analysis. This would be a peer-to-peer relationship with a 
voluntary hierarchy. 

Even if teams interact as peers for one activity, it does not preclude them interacting in 
different ways on other occasions. Less frequently, teams exist within a mandatory hierarchy 
(e.g., some of the military service branches report up the command chain to a coordinating 
CSIRT). 

Example: Take the above example. Consider that three CSIRTs agree to share 
responsibilities for the analysis of some activity that has been reported. Each takes a 
piece of the work: one examines the vulnerabilities, another the logs, and a third works 
on preparing the information that will be disseminated to coordinate all the pieces 
involved in the response and follow-up with affected sites. This latter team is the team 
that has the external-facing role, and all information flows from them to other parties. At 
some later time, other teams may participate in similar activities, but taking on different 

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roles. Even within such roles, each of the CSIRTs may have other roles they play within 
their own hierarchy (e.g., reporting to sponsors, other coordinating teams, etc.). 

The point to make here is that teams can have different roles in different situations, handling 
functions as a peer, coordinator, leader, liaison with law enforcement or media, or some other 
role. 

Who Has the Lead? 
Even if teams normally interact at the peer-to-peer level, transient, voluntary hierarchies 
often evolve for the duration of a single incident. When multiple teams are involved within 
one incident there is a need for coordination; otherwise, duplication of effort will take place, 
such as multiple teams contacting the same sites with the same information. Rather than 
waste the time of the teams and sites in this way, one team will usually take the lead for a 
given incident. Deciding who takes the lead in coordinating response to an incident is usually 
done on a case-by-case basis. Generally, the coordination is undertaken by the CSIRT 
receiving the first report or handling the largest part of the incident. Coordination can also be 
agreed upon in advance though a predefined arrangement (e.g., subscribing to a coordination 
service with mandatory subordination). 

3.7.4.3  Sites Outside the Constituency 

As a team becomes well known, it will receive requests and information from almost 
everywhere, especially if it is dealing not only with the local aspects of a single corporation 
or organization. 

Example: CERT-NL might be incorrectly assumed to be the Dutch CSIRT (judging from 
the name alone). If people do not know anything else other than there is a CSIRT in the 
Netherlands, and if they have an incident involving a Dutch host/site, they may report it 
to CERT-NL. This is true even if the site involved is not within the formal constituency 
of CERT-NL, the customers of the Internet service provider SURFnet. 

If such information should be received, CERT-NL would pass it on to one of the other 
CSIRTs that exist within the government, universities, and commercial organizations. When a 
team receives an incident report, they will have to deal with it at some level, whether they 
were the right team to report to or not. Only teams with a very specific constituency or 
service will perhaps opt for not dealing with this kind of report at all. The least the reporter 
can expect is a short message indicating that he should resend the report to another team. 

Example: Consider a medical analogy. If you experience a health problem and ask for 
help, there is no way that a doctor or nurse can ignore you (at least in many parts of the 
world). 

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115 

Note, however, that the nature of the help that you provide in such situations may be different 
from what you offer to your own formal constituency. Another factor that might affect the 
response that you offer to a site is the trust level. If you dont know the source of a report, it 
is difficult to assess the quality and relevance of the report (except that the data provided may 
verify authenticity, correctness, and relevance). 

Example: The CSIRT receives a wide variety of calls; some of these could be related to 
vulnerabilities reported by anonymous callers. The level of credence provided to one call 
may be limited; however, if the team received the same call about vulnerabilities from 
trusted members of the community (say another CSIRT or trusted expert), the latter call 
will be given a higher level of confidence that the report has some validity (or possibility 
of quality and relevance). 

When setting up a team and allocating resources and responsibilities, it is important to 
understand that requests originating from outside of the declared constituency will occur and 
must be handled. In most of the cases, a simple reply containing more appropriate addresses 
to report to will help the reporting site to contact the right parties (and limit the occurrence of 
future similar requests). To be able to give such answers, the team must prepare the necessary 
information in advance and establish policies as to what reply is adequate for what questions 
or reports. 

In the past, some teams, especially if they were responsible for a large constituency, provided 
reporting sites with more adequate addresses; and in addition to relaying this information, 
they also provided the reporting site with some kind of first aid. This often resulted in the 
reporting site receiving the same service as a constituency member. This approach gives a 
team a good reputation, but requires additional resources and might lead to the following 
problems: 
  Other CSIRTs do not like their constituents to receive help from another team. (There 
may be information that the CSIRT needs to obtain or provide to the site, but if the site 
receives preliminary information from another CSIRT and assumes this is all that is 
needed, they may never contact their own CSIRT.) 

  Upper management (or sponsors) generally do not like their teams resources spent on 

outside (non-constituent) parties. 

  The service to the declared constituency might be adversely affected due to resource 

limitations. 

One special case might arise when the reporting site does not fall into the declared 
constituency of any CSIRT. 

Example: Approximately 90% of all European nations now have a funded (not volunteer-
based) CSIRT. In many nations such CSIRTs were established for research networks, so 
depending on their policies, they may or may not handle incidents involving commercial 

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sites in their countries. In other nations up to 15 teams exist, still not providing complete 
coverage. Most likely the private users will not be served by a CSIRT. 

Therefore each team should set clear expectations and establish understandable and 
enforceable policies to deal with external requests. Whenever there is another CSIRT 
responsible for the reporting site, the reporter should be directed to report to that CSIRT or 
that team should be notified about the report. If the reporter requests complete confidence 
they should be encouraged to contact the responsible CSIRT directly and should explain the 
benefits for doing this. For example, telling them it is more appropriate to report to their own 
team as theyll receive more appropriate response or assistance, indicating that there may be 
mandatory regulations requiring they report to their own team, and/or indicating additional 
benefits their own team will attain in seeing this report potentially as a piece of a larger 
activity (the bigger picture we discussed previously).  

Additionally, since the existence of the report from the non-constituent member together with 
the request for confidence, in and of itself is valuable information to the responsible CSIRT, 
the team who originally received the report might choose to provide sanitized information to 
the responsible CSIRT about the report; without revealing any details on the origin of the 
request. (Armed with this knowledge, the responsible CSIRT might be able to identify why 
the original reporter opted for confidence and may then be able to improve their service or 
change some of their procedures to eliminate similar situations from occurring in the future.) 

3.7.4.4  Parent Organizations 

A teams parent organization might be upper management, a funding body, or shareholders. 
Like any other member of the teams constituency, the parent organization may request its 
services, from incident response to consultancy, training, or presentation delivery. 

This is an important and political topic. In most cases the parent organization will receive a 
higher priority than is normally assigned to identical service requests from other constituents. 
In the case of incidents, if the parent organization consists of operational units that are also 
possible targets of attack, a team might handle the report and immediately escalate the 
incident involving those units to the CSIRT managements attention as well. 

3.7.4.5  Law Enforcement 

Whenever an incident is related to a crime, law enforcement will become a major issue. Law 
enforcement agencies will try to 
 
 
 

learn more about the technical issues involved 

learn more about the incident itself 

identify/contact sites involved 

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117 

  obtain information on recent activities and/or damages related to the incident 

A team is in a delicate position between confidentiality provided to its constituency and the 
need to cooperate with law enforcement. A teams policies will determine the amount and 
type of information a team will voluntarily supply to law enforcement. If required to with a 
legal order (via a subpoena or other court order), a CSIRT must provide specific information 
as requested by law enforcement. Policies and procedures should define the services provided 
to law enforcement and should clearly state the circumstances under which information is 
revealed. 

To ensure good cooperation between a team and law enforcement, mutual understanding 
leading to mutual respect is necessary. Teams should be encouraged to develop a relationship 
with appropriate law enforcement contacts as early as possible to initiate these interactions. 

The policies of a team should define who is responsible for talking to law enforcement 
agencies. This includes requests from other non-local or international law enforcement 
agencies. Such requests are difficult to address and should be redirected to local law 
enforcement. Therefore it is in the interest of each team to know their legal and law 
enforcement points of contact and prepare in advance for such requests. 

Another benefit in cooperating with law enforcement agencies is the exchange of statistics 
and helping to raise awareness within the law enforcement community regarding the types of 
activity being seen by (or reported to) the CSIRT. Since the CSIRT will have first-hand 
knowledge not only about computer crimes but incidents not considered as crimes, they can 
substantially enhance the ability of law enforcement agencies to build the bigger picture. At 
the same time, law enforcement agencies may be able to share sanitized feedback with the 
CSIRT, as appropriate, regarding activity that could be of interest to the CSIRT in correlating 
other incident activity the team is seeing reported. 

3.7.4.6  Media 

Since the media has the power to influence public opinion, each team should have a media 
policy and establish associated procedures. The objectives should be 
  provide reasonable feedback and information 
  maintain the interests of sites 
 

speak for yourself and let the sites speak for themselves 

The media has its own goals and reasons for obtaining information regarding an incident. 
These goals often conflict with those of a CSIRT.42 Consequently, the media are often seeking 

                                                 
42   McGillen, Terry. CERT Incident Communications. 5th Workshop on Computer Security Incident 

Handling, Forum of Incident Response and Security Teams, St. Louis, MO. August 1993 and 

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to obtain more information than a team is willing to provide. A team should make known to 
the media the teams point of contact for media requests. Prior to their first contact with the 
media, the point of contact should be suitably trained in media interactions, including what to 
expect and how to appropriately handle situations involving the media. 

This topic will be discussed in greater detail in Section 3.8.8, Information Disclosure. 

3.8 

Information Handling 

Handling incidents is always related to handling information. Information is always the key, 
regardless of whether specific information relates to a site, a product, a new vulnerability, an 
ongoing attack, or a password. 

Information must first be collected and entered into whatever type of system the CSIRT is 
using to record and track incident reports and other relevant data. Every piece of information 
must be stored and protected for the entire time it is held by the CSIRT. Tagging the 
information according to its type and sensitivity will facilitate its further handling. Before the 
information continues to be processed it must be prioritized to ensure that the most important 
information is worked on first. After the information is reviewed and analyzed, the 
information itself or an aggregation of multiple information pieces may be disclosed to 
provide guidance and support for the parties involved, usually the teams constituency. 

3.8.1 

Information Collection 

While much of the information that a CSIRT handles will be received directly, there is also a 
need to collect information, such as proactively searching for information on the Web or 
retrieving information from other sources (technical reports, analysis, news, trusted experts, 
etc.). 

Before collecting information, it is advisable to establish a dedicated policy and suitable 
procedures to determine 
  what kind of information sources are acceptable 
  what kind of quality controls to conduct 
  how to recognize errors, omissions, or imprecise data 

If information is actively collected, it may come from one of the following two sources: 

                                                                                                                                           

McGillen, Terry & Fithen, Katherine T. Public Communications in the World of Incident 
Response. 9th Workshop on Computer Security Incident Handling, Forum of Incident Response 
and Security Teams, Bristol, U.K., June 1997. 

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119 

1.  Open source information: This includes any kind of publicly available information. The 

options range from more traditional services such as news or mailing lists to search 
engines or the Web. 

2.  Exchanges with other parties: Since other people may already possess the information 

that a team needs, exchanging information with others can directly benefit the team. The 
main problem here is knowing who has the information and establishing trusted 
relationships, so that the person/team is willing to share the information. (This highlights 
the importance of good partnership with others; see Section 3.7, Interactions.) 

Since the information available is continually changing, information collection and other 
related policies and procedures must be frequently evaluated and verified to ensure the most 
current information sources are being reviewed. 

Incoming information from other parties will have to pass through the teams triage function, 
as described in Section 3.3, Triage Function. To stimulate the reporting of information 
related to events, vulnerabilities, and potentially interesting discussion threads, the reporting 
users must be provided with appropriate support, such as reporting forms. This support could 
also include contact information, such as team phone numbers or email addresses, that can be 
used to report other types of information or submit requests to the CSIRT. 

Standardizing across policies and procedures will help the team collect information in a more 
consistent format. Having standardized the format used, further actions on the information 
such as storage, verification, categorization, and prioritization of the information will be 
much easier to carry out. 

3.8.2 

Information Verification 

Before any information can be used, some kind of verification has to take place. Usually the 
process involved will at least consider the following three issues: 

1.  Origin: The source of the information and related factors like the knowledge, 

experience, role, and function of the reporter. As with all communication, the origin may 
substantially affect the further processing of the information provided. 

Example: If DFN-CERT reports to CERT-NL an IP port scan over large IP address 
ranges originating from a Dutch university network, CERT-NL will assign a higher 
priority to this report than a report that originates from some unknown individual, 
although the report is still double-checked. 

If a report comes in from a trusted source, it might make the follow-up a bit easier, but 
there are times when the identity of the caller may make the situation more difficult or 
complex. 

Example: If the funding/sponsoring body calls, in most cases more time will be spent 
on the follow-up in comparison to other callers, regardless of the real priority. 

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2.  Content: Is the information likely to be true, or is it obviously wrong or misleading? The 

presence or absence of technical correctness of the content may affect the subsequent 
processing of the information. 

Example: Concerned constituents who have received hoax virus reports from other 
parties often send the reports to CSIRTs for verification. Hoax reports commonly 
contain information that is technically incorrect or even impossible. Although 
CSIRTs may need to alert their constituency to the fact that a hoax report is 
circulating, this may receive a lower priority than a virus report that does appear to 
be technically correct and warrants further analysis and investigation. 

3.  Distribution: This relates to the channel used for the report and possible impact on the 
authenticity of the incoming report. The possibilities range from digitally signed and 
verifiable reports to those that may have been received via an anonymous telephone call 
or even a letter via the postal service. 

3.8.3 

Information Categorization 

Information entering organizations must be categorized in some way. All information enters a 
CSIRT through the triage function; this facilitates initial categorization. Examples of well 
known categories are private vs. business, and urgent vs. non-urgent vs. garbage; usually 
such simple categories are not even formally described.43 Although categorization is implied 
by prioritization (handled below in Section 3.8.6, Prioritization Criteria), it is more 
appropriately considered as a separate and independent activity. 

The category in which information is placed affects how the information is further handled 
(e.g., storage, dissemination, distribution, and disposal). Without differentiation, all 
information must be protected to the highest level and similarly disposed of. 

Even if no explicit categorization is used, the person reviewing the incoming information will 
apply their own perceptions on the type and importance of each piece of information. Since 
these perceptions may differ among individuals, clear and concise procedures (as explained 
in Section 4.2.2, Information Categorization Policy) must be available to standardize and 
guide this process. 

Many CSIRTs have a separate process or procedure for handling contact information that is 
different than the process used for incident reports and information requests. Contacts 
(people, organizations) are usually sheltered from exposure, even to trusted fellow teams. 
Therefore specific statements for how to sanitize this type of information may be included in 
the procedures. Some teams may even have contact information as a category of its own. 
                                                 
43   Some guidelines refer to an information classification policy. We decided to use categorization 
instead. The word classified is used throughout this section and in Section 4.2.2, Information 
Categorization Policy, in its general context, not in its more restricted military and/or 
governmental context. 

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121 

Categorization is often based on the information itself. Sometimes the categorization is 
obtained following an interactive dialog with the information provider. At other times the 
information provider also specifies a category for the information (e.g., a constituent 
reporting a vulnerability or an incident). 

Information may also have to be (logically) cut into piecese.g., incident logs, where only 
specific names or IP addresses might need to be protected from disclosure, whereas the rest 
can be freely transferred to other parties. 

Example: The CERT/CC handles contact information categorization by requesting that 
the reporter of an incident state the information disclosure restrictions on the data that 
they provide in three categories: 
  other sites involved in the incident 
  other response teams 
 
If the reporting site does not provide this information (requested in the CERT/CCs 
incident reporting form [CERT/CC 1997a]), then the CERT/CC uses a default of no-
disclosure, which requires the CERT/CC to contact other sites or response teams 
without attribution to the reporting site. 

law enforcement 

3.8.4 

Information Storage 

Whenever information is stored (whether it is hand-written or stored in a computer system), 
security is of major importance. Without security, a team cannot realistically expect to protect 
the interests of its constituency and the confidentiality of the sites involved. 

This is particularly true if information is stored collectively, such as in large databases. In 
such cases the value of the collected information is greater than the sum of its parts. For the 
same reason that collected information is a great benefit to the CSIRT (to help the team see 
the bigger picture), it is also a weakness. A CSIRT might survive the consequences if a small 
quantity (e.g., one or two email messages) of information is disclosed due to inappropriate 
storage and protection.44 However, exposure of some quantity of collected information (e.g., 
the unsanitized summary of a single incident) will greatly increase impact to the CSIRTs 
reputation 

CSIRTs are attractive sites for intruders. Clearly, putting a CSIRT out of business by 
discrediting it is one possible motive for an intruder to attempt to gain unauthorized access to 
a CSIRTs data. However, another motive to consider is the information an intruder can learn 
from access to the data. An intruder might easily be able to determine to what extent their 

                                                 
44   It should be noted, however, that even a single critically important message that is disclosed could 

have a disastrous effect on the credibility and reputation of a CSIRT. 

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activities have been identified and reported to a CSIRT, identify information about vulnerable 
sites, gain information on new vulnerabilities, etc. 

Use of multiple logical databases is one useful approach to information storage. It allows 
information to be accessible, easy to use, easy to change, and flexible enough to support 
various services. 

contacts 

However the data is stored, access to the following must be possible: 
 
 
 

actions taken (or to be taken) 

incidents (current information about the activity, status and ongoing summaries as 
changes occur) 

  vulnerabilities and patches 
 
 

artifacts (scripts, tools, file remnants, etc.) 

logs or other data associated with the stored information 

3.8.5 

Information Sanitizing and Disposal 

Information sanitizing and disposal is an essential component of information handling. This 
is particularly true for a CSIRT that often has sensitive information referencing a (possibly 
very large) group of people and organizations. As discussed previously in Section 3.8.3, 
Information Categorization, information in a given category should be sanitized and 
disposed of in a consistent manner appropriate for the level of sensitivity attached to the 
information. 

Information can often be sanitized to prevent inappropriate disclosure of sensitive 
information without any adverse effect on the usefulness of the information provided to a 
recipient. 

Example: Site A finds a copy of a password file in the various intruder artifacts found on 
one of its systems that has been compromised. The CSIRT at Site A is not sure of the 
origin of the password file. Even if incomplete information exists about the origin of a 
password file, there may be enough information included in the file to indicate a likely 
source. If so, then Site As CSIRT may be able to contact the suspected source site (Site 
B) so that they can determine if their site has also been compromised. To do this the 
CSIRT sends the Site B a copy of the file with all encrypted passwords removed. This 
avoids creating further potential risks through clear text transmittal of the passwords. 
Specific information like user names and home directories remain intact, allowing for a 
high degree of assurance, without further distributing information likely to be misused if 
captured by other parties. It also protects the passwords, in case Site B is not the source 

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of the password file; the CSIRT has not given confidential information to a non-related 
third party. 

The storage of user and site-related information and the relationship between incidents and 
specific organizations have associated privacy concerns. It may be in the best interests of a 
CSIRT to keep a complete log of information, but this also could potentially affect every 
party for which information is stored. 

Example: If there is a legal requirement to provide specific information about an intruder, 
law enforcement might request all the media on which data about the intruder is stored. 
As a consequence, the team can no longer assure confidentiality of other information that 
is not related to the intruder attacks that are also stored on the same media. Knowledge of 
such instances might result in reluctance of constituents to report future problems to the 
CSIRT. To avoid such perceptionsas well as the real consequencesthe team needs to 
apply technical means to ensure that all data about the various incidents are 
independently stored and accessible. If law enforcement requests information be 
provided on one incident, only data related to that particular incident will be handed over. 

To limit possible exposure, a team might choose to store only sanitized information after a 
specified period of time or to rely on a summary containing only statistical and technical 
points. By deciding to do this, the team must expend a considerable amount of effort to 
dispose of all information that is no longer needed (notwithstanding the actual effort that will 
be needed to prepare the summaries of those statistical and technical points in the first place). 
This is particularly difficult in the case of backups, because the whole purpose of a backup 
scheme is to ensure that information is available in the long term. It is unlikely that older 
backup tapes can be easily rewritten to dispose of information that is no longer needed. 

Example: One way to handle this issue would be to use two different backup schemes: 
one for operating system and user data, another for incident-related information. This 
implies that no incident-related data is stored in the users data area. While normal 
backup tapes are reused when needed, the incident related tapes are overwritten several 
times before reuse to avoid later recovery of previously stored information. If tapes are 
no longer used, they should be physically destroyed, not just thrown away. 

3.8.6  Prioritization Criteria 

Although many types of incidents are critical or serious, even within these individual 
categories, CSIRTs will need to assign a priority to determine which to handle first. The 
importance of an incident might depend on many factors, and the priority can also change if 
new information is discovered or reported. So trying to establish and maintain a priority list 
of ongoing incidents is not easy and can in fact be a dynamic activity. 

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resources needed to deal with it 

Different schemes exist for selecting the most important incident or for ranking several 
incidents: 
 
 
 
 
 

target or source of an attack 

type or extent of damage 

impact on constituency 

type of incident 

As always, exceptions will arise that are not directly accommodated within the scheme 
selected. The scheme will need to provide some flexibility to allow for such exceptions. This 
might include initially giving an incident a default priority at the middle or top of the priority 
scale until sufficient information is available to prioritize it more appropriately. Any policies 
that affect the prioritization process must be regularly reviewed and refined over time to 
accommodate items that were once considered exceptions but are now common and reflect 
other changes in trends and needs. 

Example: Several years ago, the CERT/CC listed root compromises of systems as a high-
priority incident. However, over time (as the Internet has grown and the mission of the 
team has changed) other types of events have been given higher priority. The CERT/CC 
Tech Tip on Incident Reporting Guidelines45 lists the following priorities: 
  possible life-threatening activity 
  attacks on the Internet infrastructure, such as: 

root name servers 

 
  domain name servers 
  major archive sites 
  network access points (NAPs) 

  widespread automated attacks against Internet sites 
  new types of attacks or new vulnerabilities 

Example: New incoming incident reports are reviewed by an experienced staff member. 
His insights provide him with the ability to assign any incident to the appropriate staff 
member(s). For example, he can assign more well-known incident activity reports to 
novice CSIRT staff (such as port scans, UBC/UCE reports, or attacks using well-known 
security vulnerabilities); while more complex incidents that require more in-depth 
expertise and knowledge will be assigned to the more senior members of the CSIRT staff 
for handling. 

Continuous reprioritization of incidents must occur. Whenever new information on a given 
incident comes in, its overall priority might change. Since a change of priority also affects the 

                                                 
45   http://www.cert.org/tech_tips/incident_reporting.html 

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reporter and affected sites, these parties will also need to be informed accordingly. This is 
most important whenever incidents are downgraded to a lower priority. On the other hand, a 
seemingly lower priority incident that is suddenly upgraded to a higher prioritydue to the 
discovery of new informationcould be equally as important a reason to notify the reporter 
and affected sites. 

Since almost all teams operate with limited resources, there will be times when a team cannot 
handle all incidents reported to it. In rare cases it might be possible to hand off such incidents 
to other teams. When incidents cannot be handled, the reporter must be informed. Without 
such communications, the users are left in the dark, and rumors will arise about the teams 
apparent lack of response. This might damage the reputation of the team and negatively affect 
the overall operation. 

Most teams select some combination of prioritization schemes to generate their overall 
prioritization criteria. Commonly, teams prioritize on one scheme and then refine the priority 
by application of one or more other schemes. Depending on the scheme chosen for use, there 
are tradeoffs to be considered. The tradeoffs must be defensible and communicated, as there 
will always be individuals who claim that their incident should deserve the highest possible 
priority. We will identify some of these tradeoffs as we discuss some of the possible 
prioritization schemes in the remainder of this section. 

3.8.6.1  By Target or Source of Attack 

When prioritizing based on the target of the attack , a value is assigned based on the role, 
mission, or importance of a target site or system. Targets within the constituency boundary 
can be viewed as more important than targets outside the constituency, since the CSIRTs 
function is to serve that internal constituency. Given multiple targets within the constituency, 
the team needs to be able to discriminate between different possible targets and associate 
corresponding priority values. A targets value might be determined by the type of data held 
on it, the role it plays within a networks infrastructure, or some other factor. 

Example: Consider a CSIRT whose constituency is a manufacturing company. Using a 
by target of attack priority scheme, higher priorities would be assigned to incidents 
targeting systems that hold proprietary information (e.g., research or production systems) 
or personnel data than to those holding less-sensitive data. 

It is not always possible to determine the real source of an attack, because intruders can hide 
the source of their activity. Often, intruders weave a path through many systems (often 
crossing international boundaries) before launching an attack. As a result, the only 
information about the apparent source of an attack in an initial incident report is the site being 
used to launch the attack. This attacking site is not necessarily the real source of the activity. 

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If used, this approach is similar to that approach taken for attack targets. Values are assigned 
to possible classes of attack sources based on the perceived threat. 

Example: Consider a CSIRT whose constituency is military. Using a by source of 
attack priority scheme, higher priorities would be assigned to incidents involving attacks 
from unfriendly sources, militant organizations, or overseas sites, particularly those 
considered as hostile nations. 

3.8.6.2  By Type or Extent of Damage 

The extent of actual loss or damage resulting from an incident is sometimes difficult to 
assess. Not only can it be hard to collect this data after the fact but it is even more difficult to 
predict such data with any accuracy. The assessment will be influenced by the personal 
experience of those undertaking it, the correctness of incoming reports, and the type of 
information available to the team. A CSIRT with direct constituency authority is likely to 
have access to detailed information about an incident involving its constituency. A team with 
less authority is unlikely to have access to information at the necessary level of detail to make 
a reasonable assessment. As a result this type of scheme is more commonly seen in teams that 
have some constituency authority. 

Even if the damage is known and can be described, the same metric must be used across 
different incidents to enable their comparison.  

Example: Hospitals and emergency teams have similar prioritization schemes: 

1. 

loss of life 

2. 

injuries of humans 

3. 

loss of money / violation of rights 

If loss of money is used to determine priority, some model to determine the financial 
damage will be required. However, it is very difficult to calculate financial damage for some 
incidents. For example, it is difficult to estimate the amount of money that an organization 
might lose due to public knowledge or information disclosure relating to an intrusion. As a 
result, this criteria may be of limited use in prioritizing incidents. 

3.8.6.3  By Incident Type 

Using this criterion, known incident types are ranked depending on their overall (potential) 
technical impact; for example, a denial of service versus a privileged compromise. 
Prioritizing incidents by type can often result in too many top priority items being 
identified. Additionally, technical impact alone is not usually of interest except when a new, 
uncommon or not fully understood type of attack is discovered. As a result, this scheme is 
normally used in combination with other types of priority schemes. 

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127 

Example: Five new incidents are reported with root compromises. All should be handled 
as soon as possible, since they are considered top priority. Two are from a major 
university and involve less than five hosts at sites where the staff is experienced in 
responding to incidents. One is a denial of service attack at a hospital affecting two hosts 
that hold a medial records database and laboratory test results data. The other two 
incidents involve hundreds of other hosts in your defined constituency, since the attacker 
is running attack scripts on other sites from compromised hosts. 

The issue is to determine which incident to respond to first. Do you drop everything and 
deal with the biggest number of hosts? Do you drop the two major universities since they 
have experienced personnel available? Are other resources available within the team that 
can be utilized in the short term to help with the current reports? Can other teams be 
called on to help? Can you provide initial first aid to the hospital and follow up in more 
detail after you have dealt with the incidents that have greater technical impact? 

Now, change this scenario a bit: What if the medical hospital were actually your 
sponsors site instead, and there were still the other incidents involving hundreds of other 
hosts within your constituencyhow would this change your prioritization? 

3.8.6.4  Feedback Request Prioritization 

Generally requests for feedback can be handled differently from incident reports. The 
principle of first come, first served applies, but even in this case there may be a 
requirement to prioritize because of workload or other factors (such as available workforce 
and expertise). One method of prioritizing feedback requests is determining who gets a 
response first based on who is making the request. A request from a high-ranking official in 
the constituency or the teams funding body will usually be sufficient to move the request to 
the top of the priority list. 

3.8.7  Escalation Criteria 

Escalation is often confused with prioritization. Although the activities are similar, escalation 
is concerned with raising the importance of an activity regardless of its priority. Escalation 
invariably requires at least one level of management to become involved for decision-making 
purposes. When escalation of one or more activities occurs, it is usually a sign that a team is 
experiencing an unusual or high workload and is under even more pressure than usual.  

Escalation criteria and associated processes, procedures, and guidelines should be defined in 
advance in preparation for use. Here, too, there is a continuous need to regularly review the 
criteria and to adapt to changing needs and new developments, such as new attack styles, 
incident types, or even sponsoring organizations. 

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Note that escalation criteria can also be applied to the overall CSIRT service or the incident 
handling service. 

Example: In late 1993 the CERT/CC began receiving incident reports related to network 
monitoring attacks and the capture of user name and password information. As isolated 
events, these reports were not difficult to analyze and handle. However, as the days 
passed and more reports were received with logs that captured thousands of user account 
and password combinations, the incident handling staff became overwhelmed with the 
scope of the activity. The resources for handling reports affecting many root-
compromised systems and tens of thousands of captured user account/password 
combinations stretched the teams resources to its limits, and it was escalated to the 
director of the program. A strategy was outlined and approval given by management for 
obtaining and utilizing additional staff from within the program to assist with response 
activities.  

Example: In 1999, the Melissa virus outbreak was an incident that was escalated in the 
CERT/CC. Prior to that activity, the CERT/CC did not focus their response activities on 
virus reports. Up to that point, viruses were generally not as widespread (e.g., spread by 
sharing infected files or affecting limited numbers of users or single entities). It wasnt 
until viruses leveraged the Internet as a propagation mechanism that this type of threat 
warranted escalation. This is an example of an event that caused the CERT/CC to change 
the way in which a service was provided to their constituency.  

3.8.7.1  Individual Incident Escalation 

Regardless of priority, it may still be necessary to escalate an individual incident. The 
escalation of an incident is normally the result of an incident handler being unable to address 
one or more aspects of the incident appropriately. The incident handler ends up needing 
additional support or management oversight, or to offload other work in order to 
appropriately handle the escalated incident. As an incident evolves and new information 
comes to light it may become apparent that the person to whom the incident is assigned does 
not have the technical expertise required to handle it appropriately, causing the need for 
escalation. By its very nature, incident escalation is driven by issues similar to those involved 
in incident prioritization. 

Example: An email bombing incident is being handled by a novice staff member. During 
correspondence with the sites involved, new information is identified that indicates that 
the account being used to launch the attacks is itself compromised. The account contains 
password files from over 1,000 different systems. Given both the number of hosts 
involved in the incident and the staff members lack of experience, the incident will 
require escalation. 

Commonly used criteria for individual escalation include 

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type of data at risk 

severity of attack 

state of attack 

source or target of attack 

  number of sites and systems under attack 
 
 
 
 
 
 
  public awareness of incident 
  new attack method used 
 
 

attack on seemingly secure systems 

communication breakdowns 

impact on the integrity of infrastructure or cost of recovery 

technical ability, knowledge, and/or expertise of the individual CSIRT staff  

It is also common for a team to have escalation criteria in place to simply notify management 
of unusual or potentially important situations. 

Example: A local network service provider outside of your constituency sends details of 
an incident report to a public newsgroup. The report identifies connections that were 
made from the compromised system at their site to 1,000 remote systems. Some of the 
connections are believed to be the result of unauthorized activity. Due to limited 
resources and an inability to contact the registered users of the compromised system, the 
reporting site is unable to differentiate the legitimate connections from the unauthorized 
ones. Over fifty of the remote systems listed fall within your constituency. The incident 
should be escalated to management immediately due to the possibility of media attention 
related to the activity. 

Communication breakdowns normally result from a complaint (whether valid or not) by a 
constituent or other party to the team. The constituent may not be happy with the way an 
incident is either technically or procedurally being handled or may have a specific complaint 
about a staff member. In such cases where the teams reputation is at stake, escalation to 
management is advisable. 

When incident information is missing, a team may be unable to make progress. In many 
cases this is not a concern and the team will follow up on the incident using the partial 
information available. However in other cases, lack of critical incident information is cause 
for concern. If in such cases the team believes that the critical information exists, but has just 
not been passed to the team, the incident may be escalated to seek additional techniques (or 
leverage) to try to gain the information. 

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Example: A site within the teams constituency is an ongoing source of intruder activity. 
The team has repeatedly made email and telephone requests to the site for more 
information, but none has been provided. Escalation may allow the team to exceed its 
usual levels of service by sending a team member to the site. Another approach to 
escalate this incident would be to inform the sites management about sanctions, such as 
blocking their network connectivity if they do not react in a reasonable way as outlined in 
their acceptable use policy. 

3.8.7.2  Multiple Incident Escalation 

From an incident handling service perspective, escalation criteria must also take into account 
additional factors, including the overall workload a team is experiencing, the requirement to 
meet its mission, the need to obtain and retain how the incident fits into the bigger picture of 
overall incident activity, and the additional resources available to the team. 

There are times when a team has more incidents than it can possibly handle or it is unable to 
meet its published response timeframes. These situations sometimes arise gradually as the 
rate of incident reports increases. At other times there is a sudden sharp peak in incident 
reports. In either case escalation is applicable to enable the team to cope appropriately with 
the situation.  

The actions (often applied simultaneously) resulting from escalation are for each team to 
determine. Possibilities include applying additional resources (e.g., extending staff working 
hours or calling upon others to support the CSIRT) or reducing the level of service provided. 

Example: During the Y2K rollover, the CERT/CC manager negotiated with other 
members of its parent organization for additional technical and/or administrative support. 
Additional technical staff was used to help catalog information, contact sites by phone, 
and develop content for Web and email documents. The additional administrative support 
helped answer the CERT/CC hotline. This additional staff enabled the teams incident 
handlers to continue to focus on any incident analysis or response efforts that were 
needed. 

When a CSIRT escalates an incident by seeking additional resources it should follow 
established and agreed upon guidelines for obtaining such resources. Plans and procedures 
should have been previously discussed with the other business areas that will provide the 
additional staff.. The staff should be identified in advance and trained so that they are ready 
to help out whenever needed. Having pre-established contacts and methods for requesting 
assistance in place will facilitate the escalation process. CSIRT staff will be able to continue 
to focus on the ongoing incident activity instead of trying to determine who to call and how 
to train them. Possible resources might include 

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  other employees within the CSIRT, but external to the IR group 
  other employees within the parent organization, but external to the CSIRT 
  other teams, external consultants, or experts 
 

constituents or volunteers 

Depending on the skills and expertise and demand for the group(s) chosen, obtaining help 
might be easier or more difficult to arrange or negotiate. 

Teams are often faced with the prospect of reducing the level of service provided in response 
to incidents as a result of escalation. In such cases it is important to decide if the escalation 
should apply to all incidents or if incidents of a particular type can be excluded. In some 
cases the level of service may be reduced to a team providing direct, immediate assistance to 
the victim(s) and no more. Although this may be a necessary step to enable the team to 
recover to a steady state, it will also have other implications. In particular, it will adversely 
affect any attempts the team might normally undertake to identify the perpetrator of a 
particular incident and might also limit efforts in the analysis of techniques and mechanisms 
used by the intruder.  

One major benefit of coordinating the response to incidents is that the CSIRT is able to 
develop, see, and interpret the bigger picture, as discussed in Section 3.4.2.1. This picture by 
itself is an important service to the constituency. But it also serves as an indicator on which to 
base immediate and future resource management decisions. Therefore, a detriment in 
reducing normal services and losing your grasp on the bigger picture is especially serious 
during escalation, at just the time when the bigger picture is critical to both the team and its 
constituency. Wherever possible care should be taken to retain the necessary level of analysis 
on those incidents that could be critical to maintaining the bigger picture. 

When the team is in crisis mode and all resources are consumed by the workload or some 
other unexpected event, it is important to return to normal operations as soon as possible. 
Fixed criteria should be established to determine when a crisis is over. This will relieve the 
stress levels in team members and allow them to regroup, reprioritize, and get back on track 
with the regular tasks at hand that may have been suspended during the crisis. 

3.8.8 

Information Disclosure 

For a team to be able to operate at all, it must disclose information. However if disclosure is 
conducted inappropriately, this routine activity can result in the teams demise. To prevent 
inappropriate (wrong, not allowed) disclosure, all information disclosed must be in line with 
the teams disclosure policy. Since this policy is critical for the perception and success of the 
teams operation, it is handled in much more detail in Section 4.2.3, Information Disclosure 
Policy, while more general practical issues are discussed here. 

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There are different reasons that information may need to be disclosed and different groups or 
organizations that will receive this information. The process for disclosing information will 
differ depending on the group receiving the information and their plans for the information. 
The following is an example of the different types of groups who may receive information 
and their reasons for receiving the information. 

sites that are the target or source of an attack 

a risk management group, to help in planning infrastructure and security improvements 

Information may be disclosed to 
  other teams about a new vulnerability that has been discovered 
  other teams who are collaborating on incident analysis or response efforts 
 
  management for budget purposes 
  management for statistical reporting purposes 
 
 
 
  governmental organizations for notification or further reporting 
 

the funding body or shareholders for justification of CSIRT activities 

law enforcement for investigation or prosecution 

everybody who has a vested interest, so they are aware of ongoing activity and 
recommended mitigation or prevention strategies 

The need for disclosure can result from requests or reports. Disclosure can also result from 
events that force specific actions, such as the publication of alerts or advisories. The CSIRTs 
disclosure policy will need to take into account the circumstances relating to both the type 
and reason for the disclosure. 

Example: Whenever there is a large-scale attack targeting sites in the constituency, the 
CSIRT will inform the whole constituency rather than only the known victims. Usually 
the source of such an attack is not identified (nor might the sites targeted be identified). 
However, sometimes there is justification for disclosing the origin of attack. Examples 
include when knowledge of the origin is essential to stop the attack, when the origin is 
not willing to take corrective actions, or (in case of a real emergency) when the teams 
resources are so stretched that the only way to minimize or contain the damage is to 
provide as much information as possible about the attack (including preventive and 
reactive measures) to the constituency and let the sites handle it themselves. An important 
rationale for informing the whole constituency is to alert system, network, and security 
administrators; along with general users, to watch for and report suspicious activity that 
might otherwise have gone unnoticed. 

When defining policies, a minimalist approach should be used. For most interactions and 
disclosure, it is not necessary to reveal the whole set of information because only part of it is 

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really needed. Therefore, the policy statements should decide between need-to-know as a 
default and full disclosure in justified and closely defined exceptions. 

Example: Even if a new artifact is given to the CERT/CC by DFN-CERT, no information 
is disclosed relating to the site from which it was collected. On the other hand, the source 
may be disclosed if no need exists to hide it or if the source was public such as a 
USENET newsgroup. If the CERT/CC needs more information from the source (if it is a 
site) to analyze the artifact, it will request this information (providing reasons why this is 
necessary). If the reasons are valid, DFN-CERT will contact the site, explain the situation 
to them, and seek their permission to disclose the requested information prior to 
divulging the sites identity. Usually permission is given, but still, it is important to ask 
first. Certainly it would be much more useful to have such information as early as 
possible. 

The disclosure of information can take many different forms, each with different associated 
tradeoffs or benefits. In Section 3.5.1, Announcement Types, we discussed the 
announcement types (heads-up, alert, advisory, for your information, guideline, and technical 
procedure). These are generally public announcements. Information disclosure is clearly 
broader in scope than these examples might suggest. One could add many items to the list, 
including incident reports (aimed at specific incident-involved constituents or fellow teams) 
and internal reports (e.g., for management). 

Because the policies will also affect others, the best way to avoid misunderstandings and 
problems is to define information disclosure defaults suitable for all situations. If there is a 
choice, the data required to make the choice should be requested before the actual situation 
demands it. This will avoid any additional delays. 

Example: AusCERT initially implemented a registration process in which sites were 
asked if AusCERT could pass their contact information to other CSIRTs whenever the 
sites were involved in an incident. If a site did not wish to be contacted in regard to a 
specific incident, the site informed AusCERT, and the contact information was not passed 
on to other CSIRTs. If the contact information was needed at a later date for whatever 
reason, it was possible for AusCERT to go back to the site and request that permission. 

Privacy issues relating to a sites contact information and information about victim sites are 
obvious. Defining suitable policies and being sensitive to local laws will help to avoid many 
problems. 

Some CSIRTs provide forms for submitting information to them. Usually forms make it 
easier for both the reporter and the team to obtain the relevant data, although there are some 
tradeoffs. While the reporter of an incident or new vulnerability will be asked for answers to 

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many questions, this is much more information than they would normally provide without the 
use of a standardized form. 

Example: The CERT/CC makes its incident and vulnerability reporting forms available 
on its Web server46 [CERT/CC 1997a, CERT/CC 1996]. 

Sometimes teams or organizations place specific requirements on their constituency to fill out 
forms or to report a defined set of information. Depending on their policies, the team or 
organization may accept incomplete or informal information. 

The generation of statistics and trends is one of the most interesting services provided by 
CSIRTs beyond merely incident response. Because of their specific role, they are able to 
  develop an overall picture of incident activity for the constituency 
  provide the funding body with additional background information 
  provide a better service to the constituency 
 

raise awareness with pragmatic projections 

Part of the mission of any CSIRT is to make the best use of the information it has collected to 
serve the interests of its constituency. It is important for a CSIRT to think about the 
information it will collect and strategically plan how it will use that information, to whom the 
information will be distributed and disclosed, and what information disclosure policies and 
procedures will apply to its various interactions or collaborations with others. For example, 
the disclosure of CSIRT statistics to FIRST is discussed as a possible requirement with each 
prospective member. The prospective member will need to think about what information can 
be disclosed and in what format. 

One last issue related to disclosure of information is standardization. As the disclosure 
process can be the most visible task of each CSIRT, great care must be taken to provide a 
unified and high profile interface to the world, especially the constituency and other 
CSIRTs. The way that information is distributed should be consistent over time (e.g., so 
comparisons with previous statistics can be made). Additionally, standardization will ensure a 
consistent corporate identity for the CSIRT. (If a CSIRT is located within another 
organization, the requirements of this parent organization will have to be considered.) Items 
to consider as part of this consistent interface are 
 

format of text provided, regardless of whether the text is distributed via mailing lists or 
through online information servers (headers, outline, footers, logos) 

authenticity, through formal signatures 

 
 
content and style guidelines 
                                                 
46  http://www.cert.org/nav/index_red.html 

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4  Team Operations 

In Chapter 2, we discussed the main functions that an incident handling service is built on, 
their interactions, and the handling of information. In this handbook we set out to explain 
what it takes to build an incident handling service. Compare this with building a house. We 
showed you a drawing of the house. We described the rooms and their purposes. We 
discussed staircases, corridors, electricity, telephone, heating, and water systems. What we 
havent covered yet is how the building is operated and secured: maintenance of the heating 
and other systems, the annual chimney sweeping, the insurance procedures, and fire-alarm 
and burglar-alarm procedures. These are the operational components of the house, and in 
this chapter we describe these CSIRT operations in more detail. 

Beginning with an introduction to the main operational elements, this section will also cover 
four essential operational issues: fundamental policies, continuity assurance, security 
management, and staff issues. 

Many of these topics are not exclusive to incident handling services. Therefore it is not 
surprising that some aspects of these issues have already been covered in Chapter 3. Where 
appropriate, we will refer to that section instead of repeating the information. However, in 
this section we give a more practical approach than was possible in the policy level in 
Chapter 3. This chapter will cover useful general procedures. (Remember, procedures are the 
implementations of policy statements.) 

4.1  Operational Elements 

Operational elements are the building blocks of operations that span a wide range of ideas, 
from email systems to work schedules. We limit ourselves to those elements that bear a direct 
relationship to incident handling services, thus excluding all operational elements belonging 
to overhead, such as salary systems or coffee machines. The list of elements covered in this 
section is far from exhaustive. We will only discuss a selection of the most important 
practical operational elements. Where appropriate we provide real-life examples and include 
more detail on particularly important issues. 

 

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4.1.1  Work Schedules 

A work schedule must differentiate between normal hours and out-of-hours; it includes such 
things as work shifts (including associated personnel), out-of-hours arrangements (like 
guards or operators providing answering services), backup, and all-hands-on-deck 
arrangements. 

When considering work shifts, a good rule of thumb is to remember that after about two 
hours of routine work, you definitely need a break; but that after only one hour of 
concentrated stressful work (such as being in the midst of a big incident), you are devastated. 
When planning work schedules, continuity assurance (discussed in more detail in Section 4.3, 
Continuity Assurance) is the most important goal in relation to the quality of service 
provided. 

4.1.2  Telecommunications 

This includes traditional telecommunications like telephone, fax, cellular (mobile), pager 
and automatic response facilities. You will need this kind of technology (and other 
communications) to ensure that your organization and its members can be reached in 
accordance with your requirements and that your staff members have the technology 
available to initiate communications to the constituency and/or other parties as required. 
Implementation depends on the teams mission and service specification. 

Remember though that there is no such thing as guaranteed communication. Even the 
telephone system fails every now and then. If you cannot hear the telephone ringing, even the 
most costly and fancy technology wont help. Similarly, way down in the Grand Canyon (or 
some long, dark tunnel), you are not likely to have a working cellular phone. Be aware that 
constituents will generally be displeased if they have to wait for more than four consecutive 
rings when they try to access your service by telephone, and if they consider their need urgent 
they will be even more displeased to reach a voice message system. If they have left a 
message and do not receive a quick response (for example, within 15 minutes) they are likely 
to still be displeased. A voice box might be useful to provide a first acknowledgment and 
further information about what to expect. Modern devices will contact a predefined number 
after receiving a new call. In this way the caller does not need to know the number to reach 
the CSIRT team member. 

4.1.3  Email 

The need for a good email system in todays networking environment needs no advocating. It 
is possible to create an easy-to-use, robust email environment that is compliant with up-to-
date standards for multimedia (MIME) and security (PGP, S/MIME). However it is by no 
means a simple exercise for a CSIRT, as an incident handling service will have additional 

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demands, such as good filtering capabilities, advanced search facilities and automatic 
response tools. 

Usually CSIRTs build their own email environment based on a few standard tools, gluing 
these together and adding to them using scripts because there are no products available to fit 
their specific needs. Additionally they use a variety of converters (such as MIME, binhex, 
uudecode, zip, or gzip) and word processors because some users might use a PC office 
package to write pretty emails that are definitely not ASCII-compatible. As technology 
evolves, it is likely that such compatibility issues will become more transparent for seamless 
use. Nevertheless, it is important to consider the need for an interface between the email 
environment and other environments to handle the workflow. Without such an interface, most 
of the incoming information will not be integrated autonomously and automatically. Email 
provides an easy-to-use technology to exchange information asynchronously; and by 
prioritizing incoming email, CSIRT staff are able to handle their work more efficiently. In 
fact, it is not as time consuming as a telephone call in many cases; but in some cases, 
electronic means cannot replace direct communication. In any case, be aware that 
constituents will expect feedback in a timely fashion, whatever communication methods are 
used. 

4.1.4  Workflow Management Tools 

In any operational environment with heavy workloads and people working in shifts, tools that 
help to manage the workflow and hand-over of ongoing tasks are essential. The hand-written 
logbook is a classic example. With the complexity of todays problems and the sheer amount 
of information involved, this kind of logbook should really be obsolete (but it is not, 
unfortunately). CSIRTs need a workflow management software tool (essentially a database 
with a program on top) that enables you to follow and add to the flow of events (such as 
incidents, requests, or ongoing analysis). Excellent workflow management tools are on the 
market now, working with the usual databases. However, security of these systems is 
normally lacking; so as a rule they are only useable within a secure intranet, which may be a 
problem for off-site coverage or distributed CSIRTs. Integration with email tools, the Web, 
and the telephone system (and pagers) is necessary to collect all incoming information and to 
interconnect events. 

4.1.5  World Wide Web Information System 

The World Wide Web (WWW) is ubiquitous and currently the hottest medium in use for 
retrieving information. Certainly no team could do without it. Existing anonymous FTP 
directories are still useful to provide access to large archives with programs and documents. 
One improvement, however, is that they are at least made accessible through the Web, and 
that Web-based information can link to them. Clearly Web servers and any public information 
server for a CSIRT (providing public information) must be implemented in a secure fashion 

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to avoid the information being manipulated by unauthorized parties. The latter requirement, 
however, opposes public availability. One possible way of avoiding this contradiction is by 
placing the Web server within a DMZ (demilitarized zone) protected by firewalls and 
maintaining its security by good maintenance and control measures. To secure the 
authenticity and integrity of the information maintained, it might be useful to maintain the 
information on a master server located inside and download it to the Web server on a regular 
basis, such as every night [Kossakowski 2000]. Additional checks based on cryptographic 
checksums (such as Tripwire or MD5) are useful too. If internal information is made 
available to team members, each of these pages and all links pointing to this information 
must be removed prior to any public dissemination. 

4.1.6 

IP Addresses and Domain Name 

By separating your internal network from all other networks for security reasons, you will 
require ownership of IP address space dedicated to the team. With a Classless Inter-Domain 
Routing (CIDR) block of the Internet IP address space, it is of no consequence if only your 
team uses these numbers and not some other part of your parent organization.47 Alternatively, 
a team might choose to use some private address space (e.g., 10.0.0.0) and either network 
address translation (NAT) or a firewall for all external connections. 

The Domain Name Service (DNS) shouldnt list sensitive information such as the type of 
operating system that a particular host is running or give out a complete list of all internal 
hosts, because this might reveal information useful for a technical or social attack. In most 
cases, it is appropriate and helpful to claim an Internet domain for the team to promote the 
existence of the team and to provide an easy-to-remember interface for email or Web. Your 
domain space will typically be of the type company-csirt.some-org.tld or  
company-csirt.tld.48  

4.1.7  Network and Host Security 

An incident handling services internal computers, network, and the connection(s) to other 
networks must be securely configured and protected against attacks. This means splitting the 
internal network into compartments with different functions, with the interface to the outside 
world through a mature firewall. At least two compartments should exist: an operational 
network, where all service tasks are handled and the data used is stored, and a testbed (unless 
you perform no testing at all). Compartments should be separated, only connected to one 
another through a firewall and only when data transfer is necessary. Should a temporary 
connection be established with the testbed, be careful that it is truly temporary. Most of the 

                                                 
47   That is, the IP address space for your CSIRT would be different than the IP address used by the 

parent organization. This would, of course, require associated effort for obtaining and registering 
the CSIRT domain name and IP address, as well as any associated fees. 

48   The tld stands for top-level domain, such as .com, .edu, .org, .nl, .de, or .uk. 

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time it is not necessary to connect the testbed to other networks at all. If it is too dangerous to 
connect the test network to other machines or networks, data can be transferred by using 
removable media. 

The firewall selected will undoubtedly be influenced by the budget available. Typically, a 
dual-screened firewall will provide a high level of security; this type of firewall consists of 
one router serving the outside world, one router serving the inside compartments, and one or 
more bastion hosts to interconnect internal clients to external servers by application-level 
gateways (proxies) to prevent inside clients or servers talking directly to their outside 
counterparts. In addition a DMZ, protected by the firewall to the inside as well as to the 
outside, should be used for any server providing an accessible service to the public (WWW 
server, ftp server) or act as a gateway or transfer system (proxy server, email gateway). 

It hardly needs arguing that of all organizations a CSIRT must have its systems more than up-
to-date with regards to security patches and updates. Logging facilities, wrappers, and a 
variety of other defensive tools should help to identify and prevent intrusion attempts. But 
even the security of home systems and access from home systems and laptops must be 
considered, if they are used for sensitive work.  

Denial-of-service attacks form a special category of attacks that should be considered 
carefully, since they affect the ability of the team to perform its tasks. Having network 
connectivity available through more than one service provider can be part of the answer to 
this problem At least that way, when the main entrance is blocked, you can use the emergency 
exit to maintain at least minimal communications such as email. Section 4.4, Security 
Management, will deal in more detail with security management for a CSIRT. 

4.2  Fundamental Policies 

A number of policies are fundamental (i.e., independent of the set or level of service(s) 
chosen by a team) and must be in place. Basic issues were discussed previously in Chapter 2, 
and some examples of service-specific policies were discussed in passing in Chapter 3. This 
section will discuss in more detail fundamental policies for the teams operation. Keep in 
mind, however, that since it is most likely that service and quality specifics will affect the 
content of fundamental policies, the discussion below is generic and includes only some 
examples for clarification. 

4.2.1  Code of Conduct 

A code of conduct for an organization is a set of general rules indicating how to behave in a 
way that benefits and supports the intent of the organizations mission statement and the 
organizations character. A code of conduct applies to every staff member at all levels in the 

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organization; it is an attitude, and attitudes should be classless. It provides basic direction 
about how to react in certain situations and sets the foundation for interactions both within 
and external to the team. 

The code of conduct is a policy that one can fall back on when all other policies, rules, and 
procedures dont seem to apply, or when one is left without time to consider. It should 
become a natural professional behavior of the experienced incident handler; novice CSIRT 
staff will need mentoring to internalize the accepted code of conduct for the team. 

A code of conduct need not be more than one page of text, but there is no harm in it being 
longer and explained by example. If its too long, it probably contains procedures, which it 
definitely should not. The advantage of small size is also ease of communication internally 
and externally. Since one cannot be ashamed of ones code of conduct, why not publish it for 
the constituency and fellow teams? This will also help form the type of basic understanding 
needed for collaboration between teams. 

A very simple code of conduct example (that complements the CSIRT policies and 
procedures) is shown below: 

Demonstrate due curiosity, but at the same time ... 
show proper restraint. 

Thoroughly inform those who need to know, but ... 
do not gossip. 

Take due care, but ... 
do not forget priorities. 

Always be polite and constructive, but ... 
trust nobody without proper verification. 

Know the procedures and follow them, but ... 
never forget that the mission comes first. 

This example is almost poetic in nature; form and choice of words totally depends on the type 
of organization. Remember that its the organizations mission statement and character that 
decide the code of conduct. Another interesting example is the CSIRT Code of Conduct. This 
code of conduct (illustrated in Figure 6) is adapted from a list of behaviors that were 
developed in January 1991 by Rich Pethia, the first Manager of the CERT Coordination 
Center.49 

                                                 
49   CERT Coordination Center. CSIRT Code of Conduct. Materials from the course Managing 

Computer Security Incident Response Teams (CSIRTs). 

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4.2.2 

Information Categorization Policy 

CSIRTs must have a policy on information categorization. Without one, CSIRT staff will 
apply their own perceived categorization to each piece of information, or not attempt to 
differentiate at all. As individual perceptions may differ, resulting in inconsistent and possibly 
inappropriate service, a policy must be available to guide categorization. 

The complexity and size of this policy will depend on the teams mission and constituency. 
For instance the simplest case would be just a division between sensitive and all other 
information. All sensitive information should be treated with extra care while all other 
information is considered public. 

 

Figure 6:  CERT/CC Code of Conduct 

A slightly more elaborate scheme could define the categories internal classified for use 
only within the team; internal unclassified for exchange on a need-to-know basis with 
fellow teams; external partner, for interaction with the constituency and fellow teams; and 
finally external public, for public information. This is the approach taken by CERT-NL and 
detailed in their operational framework [CERT-NL 1992]. 

The CERT-NL scheme has the disadvantage that the distinction between internal classified 
and internal unclassified is not always clear in real life. A better approach might be to 
change the terms into fully classified, partly classified, and unclassified. The main 
difference is that the strictest category really only allows communication within the team, 
whereas the partly classified category features the need-to-know principle coupled with 

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an enumeration of more-or-less trusted communication partners including other CSIRTs, 
listed in order of level of trust. But this discussion should not imply that this issue is a matter 
of names. The only thing that really matters is that everyone follows the same method of 
categorization. A pragmatic way of setting an initial scheme in place might be to ask the team 
members separately to categorize some documents, review and evaluate how each team 
member categorized or ranked the documents (to understand the rationale for what each did), 
then reach consensus on developing a scheme that everyone can support and use. 

Military teams, for example, are expected to have the entire range of military information 
security grades (up to top secret or state secret) in place, complete with extensive 
procedures for every category on how to deal with information. 

Note also that the category selected will affect the way the information is handled (e.g., 
storage, disclosure, and disposal). As a result, polices and procedures must be developed for 
each category. Then, regardless of the content of the information, this consistent set of 
policies and procedures applies to all instances of that category. All policies and procedures 
for operational tasks should include statements on how to deal with each category. This will 
include specifying default categorization values. It makes a big difference whether a default 
is public or internal. The defaults may differ for different types of information, and how 
they are handled within each category will also necessarily differ. 

Example: The default categorization for contact information may be internal and differ 
from the default of public for publicly released advisories issued by other CSIRTs. 

Sometimes it is not clear what category information should be placed in, since it might be 
considered as a candidate for more than one category. The old adage Better safe than sorry 
applies here. Within the CSIRT environment the category chosen is normally that which 
ensures that the information has greatest protection. If at a later time new details become 
available to indicate the information has been incorrectly categorized, it can easily be 
recategorized. 

4.2.3 

Information Disclosure Policy 

One of the most important issues that a CSIRT needs to pay attention to is how it is respected 
and trusted by its constituency and other teams. Without that trust and respect, a team will not 
be able to function successfully and effectively, as people will be reluctant to report 
information to it. It is important to define an information disclosure policy for the realm of 
incident response and beyond. Without such a policy, CSIRT staff will have no guidance on 
what they can say to whom and when as they handle calls and respond to email. 

Most teams treat all information reported to them in strict confidence and do not share the 
information beyond the scope of their immediate team members. Exceptions to this guideline 

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include using generic information for trend and statistical purposes or in cases in which the 
sites and parties involved have given their consent to disclosing the information about 
themselves or their site to other specific parties (such as other sites involved in the incident, 
law enforcement, or other response teams coordinating the response to an incident). 

This policy should take into account the information disclosure restrictions that might be 
placed on information provided to a CSIRT by other organizations and the parent 
organization, which might have its own requirements (in some cases, even legal requirements 
for external audits). For example, if another CSIRT reports an incident, what can its 
constituents expect regarding the disclosure of the information reported? Will it be reported 
to law enforcement or the CSIRT management? The policy should specify limitations, which 
should be made publicly available (to the constituents and other interested parties). Under 
what circumstances must a team pass sensitive (even contact) information to law enforcement 
or a court? At the current time, we are not aware of any requirements for CSIRTs to have a 
similar legal status regarding client confidentiality (such as those for doctors or lawyers). 

Example: Consider a scenario in which CERT-NL provides the CERT/CC with 
information about an incident. Say the incident took place at an educational site in the 
Netherlands from which the intruder launched a successful attack against a system in the 
U.S. CERT-NL will pass logs and timestamps to the CERT/CC and request that they 
forward the appropriate details to the U.S. site. They will also indicate whether the 
information can be passed to other sites involved in the incident. Additionally, CERT-NL 
may provide the name of the Dutch educational site and the contact information for the 
system administrator at that site to the CERT/CC, with the understanding that the name 
and contact information is for the CERT/CCs use only and not for further distribution. 

This additional information helps the CERT/CC to understand the bigger picture and 
related activities. As a result of this information, CERT/CC is then able to correlate this 
incident with other possibly similar and/or related events involving Dutch hosts (some 
perhaps not yet known to CERT-NL). After CERT-NL receives this additional 
information, they in turn are able to help three other sites in their constituency to recover 
root compromises that were not previously detected (and that were subsequently 
identified based on the information received from the CERT/CC). 

In addition to information disclosure restrictions on information provided to a team, the 
information disclosure policy also needs to take into account requests from others to receive 
information. Commonly, such requests are for detailed technical or sensitive information. 

There are essentially three factors that determine if, to what extent, and how information will 
be disclosed. These are the purpose, target, and category of the information. 

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1.  Disclosing any chunk of information needs an underlying purpose; in other words, 

someone has a need to know this information. This need-to-know principle can be 
applied to all information. 

Example: Warning managers of a site that their machines may have been 
compromised by an http-daemon vulnerability because they are using a vulnerable 
software version requires only a bare minimum of information. No break-in-specific 
information is available, and the information needed relates to the vulnerability itself, 
available workarounds, or patches. 

Example: However, if an incident involves break-ins through a backdoor installed by 
the vulnerable software, it may be necessary to provide the relevant log, timestamp, 
and the originating IP address information, thus revealing some contact information. 

The purpose and extent of information disclosed is different in these two cases. 

2.  The target of the information is whom it concerns, e.g., members of the CSIRT 

constituency, other CSIRTs, internal management, law enforcement, media, visitors, 
experts, or the public. 

Clearly one is going to be much more restrictive when handing information over to the 
public than one would be when communicating with a trusted fellow CSIRT. 

3.  The category of the information is decided by the information categorization policy (as 

discussed previously). 

When it comes to deciding whether or not to disclose the information, it clearly makes a 
difference whether a bit of information is internal (e.g., contact addresses of 
constituents) or public (e.g., advisories). This category will affect the way that the 
information is protected. For example, public information might be relayed through 
normal email, which is only protected by the authenticity of a digital signature, whereas 
internal information would prescribe the use of encryption or a secure channel. 

Suppose there is a clear purpose in disclosing some particular information. If a decision is 
made to disclose, the information, category, and target factors will determine how disclosure 
will take place, what pieces of the information will be disclosed, and to whom. 

Example: Consider a large-scale incident, with intrusions involving thousands of hosts all 
over the world. As a result of the incident, several detailed log files have been provided to 
your team by sites involved. 

  For the CSIRTs and sites you have a trusted relationship with, you might hand over 

those parts of the log files that relate specifically to them or their constituency. 

  To other victims, you pass on the relevant (for their site) log entries to enable them to 

check their own logs, together with guidelines on how to protect against future 
attacks of this kind. 

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  You might warn law enforcement by telling them about the size and spread of the 

event, plus generic exploit details. 

  You may tell the media about the size and spread of the activity, with a warning and 

some comforting words. 

  To trusted experts you might give all the gory details (sanitizing the information to 
site-specific information) so that they might learn more about exploits, trends, and 
signatures. 

4.2.3.1  Second-Level Disclosure 

When one entity discloses information to another, it is likely that the latter will spread the 
information further. In some cases (e.g., the media) this is obvious; in other cases, less so 
(e.g., internal management). It is important to agree with the target of disclosure on what this 
target is allowed to do with the information. Once the information is handed over, it is out of 
ones control. And even if a binding contract exists stating what the target is allowed to do 
with the information, it can still leak out (e.g., through a security breach), and the originating 
party can still be affected by the repercussions (damage to reputation or even lawsuits). 

Example: With the media you can request/require that a draft is sent back for your 
comment/approval before publication. 

Fellow teams are often given detailed information, under the (often tacit) assumption that 
the information will only be used on behalf of the teams constituencies and is not to be 
spread beyond. 

One helpful approach for others is to place a label on disseminated information clearly stating 
the expected use of it (for example: For internal use within the CSIRT only). This is 
particularly helpful when exchanging sensitive information with others. 

4.2.3.2  Timing of Disclosure 

When is one going to disclose certain information, or how soon? On the one hand, it is nice to 
be certain of the facts before disclosing anything, which often takes a lot of time. On the 
other hand, likely victims should be warned as soon as possible, even if the information is not 
yet quite complete or correct. Interestingly enough, both extremes may lead to lawsuits, 
especially if a team has very explicit contracts with its constituents. 

Example: The constituents of a commercial CSIRT may become very upset when they 
experience problems that might have been prevented had their CSIRT acted more quickly 
and given them a heads-up. Being given inadequate information that leads to systems 
going down, or still being vulnerable in spite of the CSIRTs warnings may also cause the 
constituent to file a complaint or lawsuit. This kind of behavior from the constituency is 
less likely to strike a team who has no authority over, or contract with, its constituency 

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and is primarily providing advice to others (such as a national team, the CERT/CC, or 
even some large, distributed corporate teams).50 

4.2.4  Media Policy 

The media can be a powerful and useful tool to publicize and disseminate important CSIRT 
information and youll want to develop a good rapport with them. Nobody needs convincing 
that its good to have a media policy. Even if a very detailed information dissemination policy 
exists, handling the media is especially difficult. 

The main issue to consider is where will the primary interface to the media reside? Will it be 
internal or external to the CSIRT? For teams dealing with both highly technical and sensitive 
data, as CSIRTs and related teams do, it is advisable to have the media spokesperson external 
to the team. This way the spokesperson has little or no access to sensitive data, since they 
only know as much as they need to know to fulfill their function to notify the media, 
according to the information dissemination policy and media policy. Usually this information 
is heavily sanitized. Such a situation avoids the danger of too much being told to the media 
and potential lawsuits. If the spokesperson is external to the team, someone within the team 
must be responsible to ensure that the spokesperson receives continuous updates about whats 
going on.51 

Establishing a List of Media Contacts 
To avoid having publications written by disreputable or poor-quality journalists, or appearing 
in the wrong papers, it is useful to screen several media contacts and their papers or 
magazines before putting them on a list of media contacts that youre willing to work with. 
You should actively target good technical journalists and publications that you would like to 
work with. Many publications have good people on these jobs; however, security is still often 
a weak spot. Part of the collection of contacts must be devoted to means for strong 
authentication and understanding the (technical) background of the journalist and her/his 
agenda. 

Providing Rules of Engagement 
These rules inform media contacts of what they can expect from you and how you expect to 
interact with them. Do not hesitate to make clear what you expect from them, such as 
  Only contact the CSIRTs designated media spokesperson(s). 
  Do not falsify quotations or citations. 

                                                 
50   It should be recognized, however, that having no authority does not preclude someone deciding to 

file a lawsuit if the team is in a particularly litigious part of a country or region. 

51   McGillen, Terry. CERT Incident Communications. 5th FIRST Workshop on Computer Security 

Incident Handling. St. Louis, Michigan, August 1993. 

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  Provide the spokesperson a chance to comment on, edit, or approve an article before its 

publication. 

  Any violation of these rules will result in removing the media contact from the media 

contact list. 

Briefing the Media in Advance 
Taking the lead instead of waiting for the media to come to you can save a lot of time not 
having to explain actual developments over and over again. Advance briefing also allows you 
to prepare for questions that might have otherwise unnerved you. Going one step further, 
ensure that the media knows the mission of your team and give them a global sense of how 
this role is performed. Also use these opportunities to spread proactive messages. 

Specifying Out-of-Habitat Behavior 
Team members and their media spokesperson are likely to appear in public. They do not 
suddenly become invisible when there is media attention. So they should be prepared to face 
the media at any time. When unexpectedly faced with the media, the simplest solution is the 
no comment approach. While this solution is acceptable for all team members, it is not a 
feasible option for the designated spokesperson. A more elegant (and difficult) approach is to 
train the team members in media interactions and help them understand what they can say in 
public, instead of what they cannot. This is a more positive approach, and as a result they will 
project a more positive image for the media, even if they were not briefed in advance for a 
particular situation. 

Providing Outreach Through Announcements 
Using the predefined contact list, up-to-date briefings can be distributed before other public 
dissemination to provide media contacts with background information about ongoing 
developments, as appropriate. Additionally, this list can be used to send a heads-up (say for a 
new service offering) or invite them for a detailed briefing to alert them to an upcoming event 
or conference being organized by your CSIRT. 

4.2.5  Security Policy 

These days, every self-respecting organization has or claims to have a security policy, 
embracing all security aspects ranging from locks on the doors to backups, passwords, 
firewalls, and encryption. Handbooks have been written about how to write security policies 
[Wood 1998, RFC 2196]. 

Instead of doing a bad job at emulating those efforts, we will only highlight those aspects of 
security policies that are especially relevant to the readers of this handbook. 

First of all, one must consider the fact that CSIRTs and the like cannot choose but to operate 
in networked environments, which make them fundamentally vulnerable to attack. Add to 

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this the fact that CSIRTs are also very popular targets for intruders, and the prime risk factor 
is clearly outlined: a team thats suffering from an intrusion loses its ability to (re)act, and 
also the trust invested in it if the situation is not controlled in a swift and professional manner. 

Attacks on the systems of CSIRT might be motivated by the fact that as CSIRTs are high 
profile, they are sought-after targets for a wide variety of intruders. Novice intruders see them 
as an attractive target, and they are of great interest for the professional intruder, since the 
intruder might find information on companies that have experienced everything from denial-
of-service attacks to mission-critical intrusions, and much more. 

The security policy is heavily affected by other policies, because their goals must be 
protected by the security. 

Example: The information categorization policy defines variables that also occur in the 
security policy and that set the level of protection for files and documents, which must be 
implemented using appropriate technology and established security procedures. 

recovery planning (backups, etc.) 

The security policy should cover all aspects relevant for the teams computer and network 
and also consider the connection to other networks: 
  physical security 
 
 
 
 
  handling of local security incidents 
  disaster handling, business continuity 

external communication security 

local network security 

local information security 

4.2.6  Human Error Policy 

We are all human; therefore we all make mistakes. It would be nice to think that CSIRT staff 
could be immune to this trait. However, they are particularly vulnerable as a result of the 
high-stress situations in which they are placed and the responsibility associated with the 
nature of the information that they handle.  

Unfortunately, a human error policy that can be referenced and used when such mistakes 
occur is often neglected or not considered. A human error policy can help minimize and 
contain the damage inflicted by human errors. At the same time, it can give both the erring 
staff member and his/her management an opportunity to solve the problem in a professional 
and constructive way, instead of the all-too-usual strife and fear, which are counter-

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productive. A human error policy should not say Be as stupid as you want; we will always 
be nice to you. It should clearly state what possibilities a staff member should consider if he 
has made an error that may have bad results; it should clearly state the proper reactions from 
management; and it should outline the consequences. 

The following scenario might be seen as a general guideline for handling such occurrences: A 
staff member who did something that may have bad results should report it as soon as 
possible to the appropriate manager. Having an escape hatch to a trusted third party can be 
beneficial. With the error noted, managers and the staff member alike should put aside their 
sentiments for the moment and work together on containing the situation; keeping the 
wrongdoer aboard clearly is important (unless the act was obviously malicious). After the 
immediate problem has been addressed, an appointment between the staff member and 
manager (plus the trusted third party) must be made for the next business day. In that 
conversation the cause of the error must be jointly analyzed to avoid similar mistakes from 
happening in the future. If some bad habit or wrong perception of the staff member is the 
cause, it should be agreed on to change that habit or perception; checkpoints can be jointly 
defined to see if that agreement works out in the near future. Depending on the cause, 
training or educational measures might be most beneficial to allow the staff member to adapt 
to the position. 

Heres a more specific example: 

Example: Its the end of a hot week, and pressure and workload are high. A staff member 
incorrectly cut-and-pastes information about Site A into an email message intended for 
Site B. As a result, information is inappropriately disclosed. Action is taken promptly to 
inform management and Site A and Site B of the oversight. All parties are understanding. 
Methods are then sought to decrease the chance of this happening again (shorter shifts, 
easier-to-use tools, refresher training, or more coffee). 

If mistakes by any staff member start becoming regular occurrences, then additional steps 
outside of the human error policy will be necessary.52 

4.3  Continuity Assurance 

The continuity of consistent and reliable services is essential to the successful operation of a 
CSIRT. This directly reflects on the perceived competence and level of trust of a team by its 
constituency. Assuring continuity is a general operational issue covering many important 
                                                 
52   In risk management, there are known principles to deal with such situations. This includes 

separation of duty and the for eyes only principle, where only those that need to know have 
access to certain information. See, for example, Botha, R .A. and Eloff, J. H. P., Separation of 
duties for access control enforcement in workflow environments, IBM Systems Journal Vol. 40, 
No. 3, 2001, pp. 666-682. 

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aspects of operations, three of which will be dealt with below in separate sections: workflow 
management, out-of-hours coverage, and off-site coverage. Before embarking on this, it is 
useful to recognize the fact that the length of time for which one seeks to assure continuity 
may make quite a difference for the kind of problems encountered, the services that can be 
provided, and (thus) the measures to be taken. Here a division into three rough categories is 
used. Threats to the continuity of the teams operation are therefore reviewed before the more 
practical topics are addressed. 

4.3.1  Continuity Threats 

From a practical point of view, we make a division into three main categories to differentiate 
the threats that each team faces in relation to its continuity: short-term issues ranging from 
days to weeks, medium term within months, and long-term issues in years. 

4.3.1.1  Short-Term Issues 

Operational topics are mainly responsible for threats to the continuity within days or weeks. 
Four topics can be identified, which provide their own challenges and are responsible for 
most of the short-term issues: lack of time, unavailability of critical personnel, transitions 
between shifts, and unavailability of infrastructure elements. 

Lack of Time 
Lack of time can be incidental or structural. If its structural (usually caused by lack of 
funding), it is outside the scope of this handbook and normally not a short-term issue. 
Incidental lack of time (e.g., due to an unforeseen workload by a new incident with 
widespread attacks) is dealt with primarily through prioritization. Prioritization has been dealt 
with in Section 3.8.6, Prioritization Criteria. What it means for an incident handling service 
is that you let a sniffer log that is two weeks old wait a bit if at the same time all your 
attention is focused on an acute case of intrusion. If you dont have a predefined prioritization 
scheme, you will prioritize anyway, but it takes you more time to think about it, and you may 
be less consistent. Extreme lack of time may result in the need for crisis management, as it 
effects the teams service. When you have a lot of work at hand, it is helpful to make notes 
about what is going on. When the time comes to transfer the work to a colleague on the next 
shift or to a person outside your team, such as a guard or operator who will take over part of 
your work during the night, these notes will be of crucial value. Just taking notes on a piece 
of paper is the oldest form of workflow management, but it is still workable. Workflow 
management is treated below in more detail. 

Academic CSIRTs are particularly vulnerable to incidental lack of time, which is caused by 
informal and not very precise resource planning. In addition, the time needed for dealing with 
the workload is underestimated and there are not enough spare time slots and no preassigned 
tasks to allow the team a break or to complete some unresolved tasks. 

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Unavailability of Personnel 
Unavailability of critical personnel can arise at any time, because illness, accidents, and 
unforeseen events are inevitable. To avoid a single point of failure, backup arrangements for 
personnel should be made in advance. Team members should back up one another (e.g., 
buddy system). All members of a critical team should not be allowed to have the same day 
off. Regular job rotations may be considered to help spread knowledge and thus risk. 
Training to fit other needs gives personnel a perspective and helps to avoid such situations. 
Lack of critical personnel may arise during the time just before and after business hours. 
During that time most of the critical team members may be commuting to or from home. 
They may be reachable but still will have a hard time performing specific actions. This can be 
avoided by having team members stagger their business hours (one staff member works 
from 7 a.m. to 3 p.m.; while another works from 9 a.m. to 5 p.m., for example). If personnel 
are on a business trip, they might (or might not) be available to help out if their specific 
expertise is needed for some task. It is not much fun when your staff has to conduct critical 
business from a remote site like a conference, even if it might be seen as thrilling by an 
outsider. It raises a lot of problems, the impact on security being just one of them. Off-site 
coverage is discussed below, since it raises a separate set of issues. Another reason for 
unavailability of personnel is, by definition, out-of-hours. This topic is also addressed below. 

Transition of Shifts 
The transition between shifts poses special problems, even in the case where a good 
workflow management system is available. Depending on the circumstances, two cases 
should be considered: transitions between regular shifts during business hours, and transitions 
between business-hours and out-of-hours coverage. In the first case, some time must be 
reserved for a verbal transfer between shifts; gut feeling is often essential but hard to 
capture in any database. Sometimes events are not finished and open topics must be handed 
over. Additional explanations are necessary in these cases.  

Example: Some teams conduct daily briefing sessions at shift changes to identify current 
activity (new and ongoing incident reports) and provide status updates (what has been 
done, when tasks need to be completed, etc.). 

In the second case (for out-of-hours transitions), more facets of the same problem arise, 
because of the difference between both types of coverage. These differences include staff 
(e.g., regular staff vs. out-of-hours answering-service staff such as operators or guards). It 
may well be, for example, that the guards do not have access to the workflow management 
system, meaning that reporting forms will have to be transferred and analyzed the next 
business day. In addition, it is also unlikely that such guards will have the technical skills to 
respond to calls in the same way as the CSIRT staff. 

Unavailability of Infrastructure Elements 
Unavailability of critical communication paths and operational elements such as email 

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servers or information servers (WWW, anonymous FTP, etc.) will lead to the inability to 
provide specific services in a timely fashion. This could lead to complaints being lodged 
against the CSIRT or lawsuits for failure to meet contractual requirements and/or services, 
and in some cases, may have serious effects on the survival of the CSIRT and/or constituents. 

4.3.1.2  Medium-Term Issues 

For the medium term, the useful thing to do to help continuity is to get people together and 
analyze what has been going on, what went wrong, what went right, and how to use this 
information to make the service better. Post mortems after different types of incidents, to 
review activities, should be held to examine both policies and procedures and to determine 
where (or whether) improvements are needed. Other brainstorming sessions and meetings 
should be planned at regular intervals. This will highlight failures in policies or procedures. 
Another medium-term issue is the lack of funding and its influence on the teams operation 
and the level of service provided to the constituency. Staff burnout is also a serious risk to 
consider, especially in the strenuous incident handling arena (and whenever there is a lack of 
funding). Good work conditions will help to ease the burden on the individual. Encouraging 
staff to take their holidays and vacation time to help recharge and invigorate them is 
essential for the health and well-being of your CSIRT staff. Job rotation will help too; the 
latter will also help against staff boredom, which can also lead to staff burnout. Boredom is 
not unusual in handling incidents, not because of lack of work, but because of the repetitive 
nature of incident response tasks. Job enrichment and continued education also are good 
ways of motivating an individual. These can have positive benefits for the team, since your 
staff will develop new capabilities and further enrich the teams services. 

4.3.1.3  Long-Term Issues 

The ability to adapt to changes (e.g., in technology or service agreements) will affect the 
ability of the team to survive over the long term. Training of staff is therefore a long-term 
investment in continuity. Training more team members for the same functions lessens the 
impact of single points of failure, changing trends, or a team member leaving or falling ill. 
Section 4.5, Staff Issues, covers this topic in more detail. One factor that is becoming more 
important over time is working habits, especially if the team hasnt changed much over time. 
By falling into some kind of routine drill, the situation is stabilized, but this doesnt ensure 
continuity. Stabilization may limit the teams ability to adapt to change; the team may be 
vulnerable to common mistakes that are ignored since the established procedures are 
accepted as is. The ability to react to the dynamic environment of incident response is a 
continuous learning process for both the team and its staff; flexibility is a necessity because 
change must become a way of life. So, although policies and procedures are critical to 
operations and must be in place to ensure consistent behaviors, they must also be routinely 
reviewed and validated to ensure that they are still viable and that the team is still following 
them, and to determine whether there is any need for change. 

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4.3.2  Workflow Management 

Workflow management is just what it says: managing the flow of events that are part of 
workyour own work, a teams work, a companys work. Workflow management is applied 
at all possible levels, with all kinds of sophistication. A househusband will usually use only 
his agenda and his wits for managing the workflow. A company building cars will need a bit 
more workflow management. It is not surprising that much of todays practice in workflow 
management stems from the logistics area, where this has been an issue for years. 

Incident handling continuity problems arise as CSIRTs have to deal with a lot of problems 
over longer periods of time, because of the continually changing events and also changing 
team members working on these problems (due to shift changes, holidays, job rotation, and 
people leaving). For all problems, incidents, and related issues such as information on 
artifacts or vulnerabilities, the related information should be available, as appropriate, to all 
team members on duty at any time. In addition to the information about the problem itself, a 
track record of subsequent actions taken by the team, and what more needs to be done, should 
also be available. This facilitates the hand-off of ongoing incidents to the team member(s) 
taking over the problem. 

Consider the common prime carriers for information coming into a CSIRT: email, files, 
faxes, telephone notes, and letters. How to make this available to all at any time is not an easy 
task. Applying numbers to incidents and tagging all information on the incident with some 
type of tracking number or ID is the very first thing to do; this point has been extensively 
covered in a previous section. That done, one could opt for the classical system: All 
paperwork (faxes and letters, possible telephone notes too) is indexed and archived, and all 
electronic files are numbered and stored (email and files are usually stored in different places. 
Then there may also be Web pages to consult, which makes the number of archives to consult 
(with regard to one incident) a discouraging four. Some teams use a fifth archive (some sort 
of database) for tracking records of the incident. 

Though the aforementioned classical solution may assure continuity, it is hardly an efficient 
way of doing this, and it may backfire on the team in rough weather when every minute 
counts. Therefore the ultimate goal should ideally be to have no more than one archive, at 
least one archive that meets the eye. Any supporting structure should be hidden from the team 
member using the archive. 

Eliminating paperwork is not that difficult. Scanning techniques are quite sophisticated today 
and relatively inexpensive. Incorporating these tools and techniques into everyday incident 
handling practices would be a good thing to do; recognizing, however, that it is not one with 
a high priority, since the vast majority of information is electronic to begin with. If 
documents are only maintained in electronic form, it is important to consider that legal 
requirements or rights are often affiliated with the original document or the signature of the 

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person sending a letter, etc. So all hard copy materials that have been transferred to the 
electronic archive should be maintained a for requisite length of time, as appropriate. 

Perhaps the best current practice for integrating email, files, and access to the Web is using a 
Web browser. Converting email archives to the Web is possible most of the time (certainly in 
UNIX environments). Accessing files from a browser is easy. Search functions and indexing 
are also easily implemented. The Web solution is still one that a team will most likely have to 
devise and customize. 

One further degree of complexity now has to be added: how to properly keep the history of 
an incident. In the above example one could simply write notes as they arise into some file or 
database and make it accessible through the Web or groupware system. But this still means 
that the majority of the actual management of the flow of events itself is left to the person on 
duty. This person has to do all the routine work, like checking on open incidents regularly, 
(more than likely a manual process, possibly helped with the use of some in-house-developed 
tool or script), updating information, annotating the record with new information, sites, etc. 
Where possible, any routine work should be carried out by the machine. There is enough 
good software around to undertake workflow management. 

The groupware vendors (Lotus Notes, for example) are working hard on offering these kinds 
of solutions in a single software package. This development is of great interest to CSIRTs. 
But a common problem of workflow management software that is mainly developed for 
internal networks is a lack of security. This lack of security usually makes it unfit to use in a 
distributed environment. Teams might adopt secure tunnels over the Internet to undertake 
distributed work. Using a Web browser to access the workflow software (and other tools such 
as an email client) through the secure tunnel may solve the security problem in an elegant 
manner. 

Essentially, workflow management software uses an underlying database in an intelligent 
way to keep track of changes occurring in the database (or changes not occurring!).  

Example: A new incident is identified. It is assigned some type of tracking ID and is 
stored in the database. From that point on, all related events associated with it are logged. 
Every incident has a status field ranging from new to closed. Lack of status change 
may trigger alarms. (Note that this is just the core functionality; many additional 
possibilities and other associated actions would be tracked and recorded throughout the 
life cycle of the incident.) 

However, integration between such tools and Web or groupware archives is still lacking in 
most cases, which is a serious problem. Full-text search engines are available, but must be 
used in addition to other products. There is light at the end of the tunnel; Web gateways for 
these tools are beginning to appear, and ideally these will enable the use of a workflow 

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management system through a Web browser. Groupware suites are starting to incorporate 
workflow management capabilities, though this is not yet mature from the CSIRT 
perspective. 

In conclusion, workflow management is important to consider for helping to assure a 
CSIRTs continuity of work. Many practical solutions for pieces of the problem exist, but 
there is no single, comprehensive solution to date. Some tools can be excellent, but need 
tailoring and programming to adapt databases and workflows to local needs. 

4.3.3  Out-Of-Hours Coverage 

If your service specification calls for out-of-hours coverage, it should be quite clearly 
outlined what is expected during out-of-hours and what is not. Once that is clear, one can 
identify the functions that need to be available during out-of-hours, and the level of service 
expected. The quality parameters (such as response times) may well be different between 
business hours and out-of-hours. Without clear descriptions and guidance (along with 
appropriate policies and procedures), constituents will likely call for help even if they have 
minor problems. Each of these functions should then be analyzed with regard to the 
continuity aspect; what works trivially during the day in the office may well be a big problem 
in the evening at home. Any problems occurring should be eliminated. 

Examples of typical out-of-hours problems are given below. Off-site coverage is handled in 
the next section. 

4.3.3.1  Hotline Coverage 

There are different choices for how to implement the coverage of a hotline.53 The most 
important issue is to define who will answer the hotline calls during out-of-hours: a person 
from the team on duty, another staff member, or an answering service such as voicemail, a 
guard, or a call center of a telecommunication provider. 

That decided, there are several possible ways to relay the calls to the person who will actually 
handle the call. If a team member will answer calls directly, this can be implemented using a 
call-relaying mechanism. Alternatively, a hotline number for out-of-hours calls can be 
disseminated to the constituents, pointing to an alternative contact number. Last but not least, 
the person on duty might physically stay in the office during their shift. 

If hotline calls are relayed through other staff members or external parties, they can have a 
list of home telephone numbers for each team member, or a hotline number can be provided 
to call or page the staff member. 

                                                 
53   Sometimes referred to as a help desk, customer service line, call desk, etc. 

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Depending on the choices made, there will be constraints to quality parameters (such as 
response times) that have to be considered. Issues such as provision of home equipment vs. 
time to travel to the office to respond to a call will also need to be considered. 

4.3.3.2  Escalation 

If things go awry in the daytime, escalation is usually as easy as asking other team members 
to help; but what happens out-of-hours? Thought should be given to this issue. For most 
teams, it might be a good approach to consider having at least one other team member 
available as a backup on short notice. Alternatively, a backup might be chosen in a crisis 
situation by finding out who is available. Since a crisis situation will affect team operations, 
the position of a manager-on-duty who decides and addresses conflicts might be 
appropriate. 

4.3.3.3  How to Reach Other Teams or Customers 

Your team is not the only one undertaking out-of-hours coverage. Evaluate your existing 
working relationships with other teams, customers, and others based on their availability 
outside business hours and build on these relationships, as they might be willing to provide 
you with other emergency numbers that they would not normally disclose. Note the time-
zone problem: what is out-of-hours here may be business hours elsewhere and vice versa. 
National holidays differ across the world. Even the observance of public holidays may differ 
within a single country. 

Example: The time-zone problem can be an advantage too. Cases have been reported 
where U.S., European, and Australian teams have used their geographical separation, 
covering many time zones, to enable continuous work on a problem (like an incident or 
vulnerability analysis and resolution). As the business day of one team came to an end, it 
would hand off the problem to another team whose business day was just beginning, and 
so on. 

Example: Independence Day (celebrating the independence of the U.S. from the U.K.) is 
traditionally observed in the U.S. on July 4 of each year. If this holiday falls on a 
weekend (Saturday or Sunday), some companies in the U.S. may choose to observe it on 
the Friday before or the Monday after. Clearly this holiday is not observed in other parts 
of the world. 

Example: The U.S. Veterans Day holiday is traditionally observed by only U.S. 
government (local, state and federal) and military agencies. Banks, other businesses, and 
organizations in the U.S. may or may not observe this holiday. 

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4.3.4  Off-Site Coverage 

Off-site coverage is different from out-of-hours coverage because the regular services must 
be provided from a remote location. Usually there have to be good reasons (such as a disaster 
or some other crisis situation) to continue your business-hours service, with on-duty 
personnel being off-site (at a conference venue, at a constituents site, or even a backup 
facility). This results in most of the same problems as out-of-hours coverage and more, 
because the level of service expected will be the same as that provided in business hours from 
your normal base of operations. The constituents need not DQGSUHIHUDEO\VKRXOGQRW EH
aware of your specific situation. The focus should be addressing their problems and not 
concerning them with the steps that you have to take to provide them with service. Obviously, 
due to the complications that it presents, off-site coverage should be reduced to an absolute 
minimum. 

The location (e.g., their homes during out-of-hours, or hotel room at a conference location) 
from which people on duty work is not necessarily known in advance. This poses extra 
security problems that usually have to be evaluated in a very short period of time. Depending 
on the circumstances, a decision must be made either to reduce the level of security necessary 
to provide a specific service or to keep the high security level but prevent access to the 
internal CSIRT network due to lack of necessary security measures. In such cases the security 
of the team will outweigh all other considerations. 

There is obviously a good reason for the team members involved to be off-site in the first 
place. They will have additional tasks to undertake (e.g., a presentation at a conference or a 
customer meeting) in addition to any incident handling work they are requested to conduct 
off-site. The priorities associated with the tasks must be clear and determined in advance. 
These priorities determine which tasks take precedence and which can be left until the next 
day, when they return to the office, or until another person is available. 

4.4  Security Management 

A CSIRT must clearly place great emphasis on guarding its own security, but to cover all 
relevant aspects is beyond the scope of this document. 

However, the specific CSIRT issues addressed in this section lead to the need for additional 
comments. The following factors (which are generic for the majority of installations) must be 
taken into account when considering the goals for CSIRT security management: 
 
 
 

integrity: to ensure that information stays the way it was intended to be 

confidentiality: to get what you are allowed to get and nothing more 

availability: to get what you want when you want it 

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authenticity: to know for sure the origin of the information  

exclusivity: to ensure that only the intended recipients can use the information 

 
 
  privacy: to guarantee that the interests of persons and organizations are protected 
  obligation: to guarantee that due diligence requirements are fulfilled 

4.4.1.1  Use of Encryption and Digital Signature Applications 

The use of encryption and digital signature applications is unavoidable for any CSIRT. They 
offer good possibilities for securing data on the teams computer systems and during data 
transfer through unsecured networks. Cryptographic methods can also ensure authenticity to 
protect connections (especially from outside) into the teams internal network. (See below for 
more considerations.) Between the team and cooperating partners, common encryption tools, 
such as S/MIME and PGP or GPG,54 enable secure communication of sensitive data (such as 
the analysis of an incident, a new artifact, or a summary of recent trends on a routine basis). 
Log files related to intrusions can be encrypted and transferred using email to and from 
constituents to keep sensitive information about victims and the systems involved private. 
With regard to internal encryption, one can choose proprietary standards. Several good 
possibilities exist but these will not be discussed further in this handbook. When dealing with 
the outside world, you have to opt for (de facto) standards such as PGP and GPG. S/MIME is 
becoming more prevalent and may also become a de facto standard, judged by the support it 
receives from Microsoft, Netscape, and the rest of the user community. In addition to 
confidentiality, authenticity can be achieved; however, there are other issues that arise as a 
result of this (see key management and certification issues below). 

Serviceable programs such as S/MIME and PGP/GPG have been available for years. Using 
these programs, the user is often confronted with the program and technology directly 
(including the integration with the email client), but strong measures are available. S/MIME 
is now integrated in popular commercial email clients (Netscape, Microsoft) as well as open 
source software (Mozilla). PGP Version 6.x/7.x, as well as other OpenPGP implementations 
like GPG, have brought more user friendliness, graphical user interfaces, and better 
integration with email clients. 

4.4.1.2  Key Management and Certification 

Use of cryptography introduces a key management and certification problem. S/MIME and 
PGP/GPG use asymmetric encryption (also known as private key encryption) for providing 
strong authentication. This avoids the weaknesses of symmetric (also known as single or 
secret) key encryption schemes, since the secret key must be known to all communication 
partners. Hence it is impossible to provide authenticity of the origin and destination (since the 

                                                 
54   GPG or GnuPG is an open source implementation of PGP supporting the OpenPGP standard 

developed in the IETF. GPG is compatible to newer PGP releases, but does not support PGP 2.6.x 
versions. 

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key is shared). However, asymmetric encryption makes use of two keys (which are 
interrelated) for each person/role. While the public key can be distributed to everyone 
without compromising the authenticity, the private key must be protected like a password. 

Example: In the asymmetric encryption scheme, if Moira wants to send Don an encrypted 
email, Moira uses Dons public key to safeguard the text that she writes and transmits it 
to Don, who then is the only one who can decrypt it using his private key. In addition, 
Moira uses her private key to sign the written text she sends, so Don is able to verify the 
origination using her public key. 

The key management problem touches both public and private keys. The private keys have to 
be stored safely; if somebody controls your private key, he can decrypt everything you can 
decrypt. Unlocking a private key is done using a type of password called a passphrase. This 
passphrase must be well protected to ensure security. Some people carry their private key on 
a diskette or other removable media like a USB token, though one might wonder about the 
security that such an approach provides, especially if the diskette is not equally well 
protected. 

Beware, though; using strong cryptography without common sense is no cryptography at all. 
If you use a three-letter passphrase for unlocking your private keys, and youre not doing this 
on a totally isolated system, then you break the chain of security. Therefore the availability of 
a strong program is not the only critical issue; it must also be used in the right way. Similar 
problems are related to the storage of passwords and passphrases to unlock the private keys 
on computer disks or within programs and scripts. 

One problem with public keys is the need to check whether the public key you obtained is 
authentic and really belongs to the person that the key is attributed to. This is why 
certification authorities for S/MIME or PGP/GPG are so common and necessary today. 
Trusted third parties (TTPs) like Verisign Inc. will sell users a key pair (public and private 
key). (One has to trust that the TTP does the appropriate checks to verify identities before 
issuing such keys.) From a users perspective, it is absolutely necessary to be the only person 
with access to the private key. If you buy a key from a TTP, the TTP will sign your key, thus 
making it more trustworthy. Caution should be exercised when relying on TTPs, however, 
because they rely on proprietary policies relevant only for their users and customers. None of 
these systems currently provides a digital identity for network citizens worldwide to reliably 
compare personal ID systems (as with, for example, visual inspection of a passport55). 

Where users can sign or accept each others key themselves, the same problem arises: how to 
check the authenticity of keys. If no direct relationship to a person exists that can be used to 

                                                 
55   Although, of course, an argument can be made that such comparisons are also not 100  percent 

foolproof, as crafty criminals have certainly, in the past, falsified passport credentials. 

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verify the fingerprint, users have to rely on a web-of-trust, which means another user has 
certified that he verified the binding between a key and its user. 

Example: Moira signs Dons public key; her colleague, Ann, who does not know Don, 
but wants to send secure email to him, obtains Dons public key and sees Moiras 
signature on his public key. As Ann had (on some previous occasion) verified that 
Moiras public key is really her key (after some personal meeting where both exchanged 
the fingerprints of their keys), Ann can compare Moiras fingerprint/signature on Dons 
key. Ann might then also trust Dons key without needing to personally check with Don. 
This is the web-of-trust concept of user certification of PGP, which builds and expands 
the trust relations within smaller user communities. Stated differently: someone you 
know and believe has done the right thing to verify a key will be the link to someone you 
dont personally know. 

If and when a CSIRT should sign keys (either with their team key or with the key of an 
individual team member) is a question to be addressed. One might argue that if a CSIRT has 
signed the key of somebody who then proves to be untrustworthy, this action reflects poorly 
on the CSIRT itself. Although technically speaking this is not true, a CSIRT will try to avoid 
any problem and might choose not to sign any key with their team key. 

Example: The CERT/CC has chosen not to sign any keys from the outside world with the 
CERT/CC team PGP key. 

Example: CERT-NL uses only its master certification key to sign very trustworthy 
people. CERT-NL members have a less restrictive policy on what they can sign using 
their personal keys. 

4.4.1.3  Firewalls and Network Security 

Ideally the teams network is separated from the outside world by a well-designed firewall. 
The outside world includes the teams host organization [Chapman 1995]. Firewalls are not 
the ultimate solution and must be supplemented by appropriate authentication and 
authorization throughout the network. To recognize attacks and possible breaches of security, 
adequate administration and control must be ensured. Firewalls are useless if, for example, 
log files are not regularly checked for suspicious activities (at least daily). Tools such as 
Swatch56 and logsurfer57 allow for online recognition of suspicious log-file entries and help 
with analyzing and data reduction options. 

Consider redundancy issues when building the local network. Critical components are not 
only the firewall and related hosts, but also servers (shadow file servers, shadow disks, 

                                                 
56   http://swatch.sourceforge.net/ 
57   ftp://ftp.cert.dfn.de/pub/tools/audit/logsurfer 

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surplus workstations, and hot spares). To protect against interrupted power supplies, backup 
power arrangements should be made.58 

Do not forget to have extra backup tapes in another location; think of fire or other disaster 
situations, for instance. But also recognize that the other place may be less secure than your 
own, so a good practice is to encrypt the backups. Encryption might be also an option by 
providing specific services like a file server. Consider the use of cryptographic systems like 
Kerberos or something based on it (like AFS) on your local network, or at least use file 
encryption for sensitive data. This will give additional protection if the firewall cannot block 
each attack. 

4.4.1.4  Isolated Networks for Tests 

Any testbed (e.g., for viruses, artifacts, programs with unknown behavior) must be separated 
from the operational or live production network of a CSIRT. This ensures that the availability 
and integrity of the mission-critical computer, communication, and network systems will not 
be affected by any testing, analysis of malicious code, contamination, or denial-of-service 
events that could affect the ability of the team to perform its function and that could ruin the 
public standing of the team. This is even more true if, for example, a virus escapes or an 
attack involves other systems of the Internet. 

Example: In 1998, due to a flaw in the INND news daemon software, unintended break-
outs of USENET news control messages, created for testing purposes by a CSIRT, 
caused thousands of /etc/passwd files to be sent from vulnerable news servers all over the 
world. It was very embarrassing for the CSIRT and could have been prevented had the 
team members performing the tests used an isolated testbed or ensured that they had 
secured their testbed properly.59 

4.4.1.5  Providing Off-Site Access to Local Facilities 

When working at home or on the road (using a mobile computer), special care must be taken 
to offer secure access to local systems holding email and workflow management tools. The 
firewall design should not be punctured to allow for this kind of access. Thinking about this 
paradox of security versus outside access, one soon arrives at essentially only two possible 

                                                 
58   Uninterruptible power supplies (UPS). 
59   Another subsequent effect of this testing was that the CSIRT now had all these password files to 
cope with.  What should they do? Contact the sites to tell them that the test script went awry and 
the sites INND software was vulnerable? Should they send the password files back to the sites?  
If so, certainly the CSIRT would not forward these files without sanitizing them first (to remove 
the password field content), so then the problem would be how to do this mass sanitization for all 
the files and get them sent to the appropriate contacts.  That in itself also poses a problem. Does 
the team have all the (correct) contact information? What effort would be needed to look up 
contact information?  Should the team even undertake this task? Are the sites within or external to 
their constituency? Is follow-up contact with external sites part of their mission and goals? As can 
be seen, there are lots of issues to address in this circumstance. 

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solutions. The first one is dialing into the network. This is in itself relatively secure, 
especially when the access procedure uses strong authentication such as one-time passwords 
or challenge-response cards. Other protection schemes rely on dialing back to a 
predetermined number. Even then, strong authentication is mandatory. Tapping remains 
possible; however, this too can be secured using encrypting devices or secure telephones and 
equipment (in the U.S., for example, using devices such as aSTU III or STE). Physical 
protection against loss or theft of a mobile (laptop) computer and the data stored on it or 
associated media is another security issue with which to be concerned. 

The second solution is using public networks, probably the Internet. The only right way to do 
this is using end-to-end encryption to build a tunnel with strong authentication and 
encryptiona virtual private network (VPN). The neatest solution is application-level 
encryption, but this is often not feasible or not good enough. 

As an alternative a tunnel can be built from a laptop (or other device) to the teams network 
on the network level. Products like SSH (Secure Shell) are built for this purpose. Experience 
teaches however that all these tools should be implemented very carefully and thoughtfully, 
otherwise the cure can be worse than the disease. As many tools are relatively new, efforts 
should be made to ensure adequate testing and protection; in addition, some of these new 
tools can contain software vulnerabilities.60 

But just protecting the communication link between a home system and/or notebook and the 
teams network is not enough, as the security of the systems involved might also affect the 
network directly (escape of a computer virus into the teams network) or indirectly 
(sensitive data is copied from a home system without notice). Therefore many of the security 
considerations must be applied to such systems as well. It might be easier for remote access 
to restrict the necessity to a minimum or disallow the handling of categories that are 
especially sensitive. 

4.4.1.6  Physical Security 

A CSIRT may not have full authority to implement all aspects of physical security itself. 
Physical security is usually provided by the parent organization, and must be enhanced to 
meet the requirements of the CSIRT if possible. Physical break-ins can be at least as 
damaging as intrusions over the network. Lock regimes, clear desk policy, authorization of 
personnel and visitor arrangements should be taken into account. In addition, consider 
document handling: lockers, safes, litter deposit, shredding. Do not forget to consider the 
physical location of faxes and printers, or even hotlines inside the safe environment. 

                                                 
60   See, for example, the following CERT Advisories: Trojan Horse OpenSSH Distribution, 

http://www.cert.org/advisories/CA-2002-24.html and Multiple Vulnerabilities in SSH 
Implementations, http://www.cert.org/advisories/CA-2002-36.html. 

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Telephone conversations should not have the possibility of being overheard by other persons, 
such as guests. 

Concern should be raised over wiring schemes in the building, location of hubs, etc., with 
regard to the possibility of eavesdropping. Distrust all other public communication 
mechanisms, especially mobile ones, which are susceptible to eavesdropping (although this is 
not a distinctive physical security problem). Consider using encryption for connections in 
question. Encryption can also be applied to protect file systems and backup media, and by 
that provide more security in case the physical security cannot be guaranteed 100 percent. Be 
aware that besides technical means, information leakage can also occurvisitors or guests 
might (covertly or overtly) seek information, for example, in the normal course of small talk 
or by just being in the room when incident-related information is discussed. 

Consider janitorial or other cleaning staff, employees of the electricity company, or anyone 
else who might have access to your facility. Often these people are overlooked as they are 
low-profile and mostly invisible; however, they can completely ruin your security design. 
Ensure that your physical security plans take them into account. 

Example: The CERT/CC offices are not accessible by cleaning staff unless a CSIRT staff 
member is present or the cleaning staff is escorted by a security guard. 

4.4.1.7  Disaster Handling 

In case of disasters, be it a highly destructive network intrusion, sabotage, fire, or other 
natural disaster, priority schemes and escalation procedures should be in place: what to do 
first (and what to neglect) and whom to warn.61 Some definition should exist of when to enter 
disaster mode (and when to return to normal operation). When disaster mode is in effect, 
people who do not normally belong there will tend to crowd the office. Even then, security 
still counts, and these disaster-induced risks should be taken into account accordingly. 

When a fire is raging, the fire fighters will be everywhere, including inside your superbly 
secured control room or computer room. Are the consoles locked? What sensitive documents 
are lying around? Whats the printer printing? Its virtually impossible to impose the strictest 
security even in such places, but make it a part of disaster handling to assign somebody to 
look after these security issues when a disaster strikes (without endangering them, of course). 
This should include gathering sensitive and critical information, including hardcopy 
documents and electronic media. It is also useful to conduct a post mortem to review and 
evaluate the CSIRT processes and procedures to identify what worked well and where 
improvements might need to be made. 
                                                 
61   Although disaster recovery and business continuity operations (in the parent organizational sense) 

are not covered in this handbook, it is important for the CSIRT to ensure that it has previously 
established relationships with those groups in the organization who are responsible for these roles 
(e.g., disaster recovery plans and/or continuity of operations plans). 

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165 

If the constituency relies on the operation of the CSIRT, take precautions to provide a backup 
in times of crisis and disasters. After the critical event, measures must be in place to allow for 
a quick recovery. 

4.4.1.8  Handling Internal Security Incidents 

Organizations like to keep quiet about internal incidents. If nothing is articulated (written) in 
the security policy, nothing will be said on this topic; keeping quiet is the natural reaction. 
But it is often the wrong reaction. With the possible exception of internal attacks, incidents 
will have some involvement with systems outside the CSIRTs network. As a result, other 
external people may be aware of the activity and may disclose the information publicly. 
Certainly if the perpetrator knows of the attack, and as intruders may brag and publicize their 
activities (supplying proof to support their claims); the incident may become public even if 
internally no one reports it. This is a good example for the rationale behind having in place a 
human error policy (see Section 4.2.6) and the supporting procedures, so that in such 
circumstances, the individual can (is encouraged to) report such activity. CSIRTs must 
practice what they preach, and internal attacks against the CSIRT cannot be ignored. If an 
incident occurs internally in the CSIRT, it should be reported, just as any other internal (to the 
organization) incident. CSIRTs must prepare for and address such incidents, not just for the 
obvious reason of containment but also because if they try to hide them and someone 
subsequently exposes the activity, then the teams reputation may be irreparably damaged.  

This holds true for organizations whose business it is to deal with security incidents. If you 
admit a problem, people will ask you how come your security is not good enough, and you 
have to explain what happened. If you hide a problem and it leaks out, you may find yourself 
out of business; people will not trust you any longer (because of your silence and your 
insecurity) and people will not trust your expertise any longer because you were not able to 
protect your own systems. 

Clearly one should attach high priority to internal incidents, however not to the extent that 
other high-priority issues are ignored. A careful balance must be struck here. 

4.5  Staff Issues 

Regardless of the provision of appropriate documented policies and procedures, CSIRT work 
is essentially service based. As a result, there is an inherent reliance on competent and 
trustworthy staff to effectively execute a teams policies and procedures and to exhibit 
diplomacy when dealing with constituents. Hence CSIRT staff play a pivotal role in ensuring 
the mission and service of the operation. In this section we will discuss the issues related to 
identifying, hiring, training, and retaining suitable CSIRT staff. We will also discuss arrival 
and exit procedures and extension of staff. Additionally we will discuss possible alternatives 

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to consider when the core CSIRT staff are insufficient either in numbers or technical skill to 
address situations that might arise. 

4.5.1  CSIRT Staff 

Many people incorrectly consider the most important attribute in CSIRT staff to be their 
technical experience. Although technical experience is a desirable attribute, by far a more 
critical criterion is an individuals willingness and ability to follow procedures and to provide 
a professional interface to constituents, customers, and other parties interacting with the 
CSIRT. It is a more desirable approach to hire individuals with less technical experience and 
good interpersonal and communication skills, and then train them in CSIRT-specific technical 
skills, than vice versa. Certainly this handbook itself provides a good start for educating and 
enhancing the understanding that all staff members will need in order to interact with other 
teams and provide a suitable service. 

Having a wide range of interpersonal skills is important, because team members are 
constantly communicating with each other, their constituency, and other parties, such as other 
response teams. The reputation of a team relies on the professional interactions that its team 
members undertake. Interactions of a team member who is a technical expert but possesses 
poor communication skills may severely damage a teams reputation and standing in the 
community, while those interactions that are handled professionally and competently will 
serve to enhance the CSIRTs reputation as a valued service provider. Hence attention to an 
individuals interpersonal skills is extremely important.62 

The following interpersonal skills are important for incident handling staff and are listed here 
(in no specific order): 
 

common sense to make efficient and acceptable decisions whenever there is no clear 
ruling available and under stress or severe time constraints 

 

effective oral and written communication skills (in native language and English) to 
interact with constituents and other teams 

ability to follow policies and procedures 

  diplomacy when dealing with other parties, especially the media and constituents 
 
  willingness to continue education 
 
 
 
                                                 
62   Fithen, Katherine T. Hiring IRT Staff Interview Process. 8th Workshop on Computer Security 
Incident Handling, Forum of Incident Response and Security Teams, San Jose, California, June 
1996. 

integrity and trustworthiness to keep a teams reputation and standing 

ability to cope with stress and work under pressure 

team player 

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167 

  willingness to admit to ones own mistakes or knowledge limitations about a topic 
  problem solving to address new situations and efficiently handle incidents 
 

time management, in order to concentrate on priority work 

From a technical perspective, each incident handler requires a basic understanding of the 
underlying technology and issues on which the individual will base their expertise. The 
nature of these skills is similar, regardless of the underlying software and hardware 
technologies in use by the team or constituency. 

The following technical foundation (with a few general examples in parentheses) is important 
for incident handling staff: 
  public data networks (telephone, ISDN, X.25, PBX, ATM, frame relay) 
 
  network protocols (IP, ICMP, TCP, UDP) 
  network infrastructure elements (router, DNS, mail-server) 
  network applications, services and related protocols (SMTP, HTTP, HTTPS, FTP, 

the Internet (aspects ranging from architecture and history to future and philosophy) 

TELNET, SSH, IMAP, POP3) 

  basic security principles 
 
 

risks and threats to computers and networks 

security vulnerabilities/weaknesses and related attacks (IP spoofing, Internet sniffers, 
denial of service attacks, and computer viruses) 

  network security issues (firewalls and virtual private networks) 
 

encryption technologies (TripleDES, AES, IDEA), digital signatures (RSA, DSA, DH), 
cryptographic hash algorithms (MD5, SHA-1) 

  host system security issues, from both a user and system administration perspective 

(backups, patches) 

It is imperative that some subset of the team has an in-depth understanding of the full 
spectrum of technologies and issues in use by the team and constituency. This additional level 
of expertise is a resource that will be used to broaden and deepen the technical resource and 
capability of the team and educate other team members through training and documentation. 
It also ensures that the team can cover smaller subsets of a constituencys technology base 
and can provide a full range of services. The following specialist skills to consider are in 
addition to an in-depth understanding of each of the technical skills listed above: 

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technical skills such as programming, administration of networking components (e.g., 
routers, switches) and computer systems (UNIX, Linux, Windows, etc.) 

interpersonal skills such as human communications, experience in presenting at 
conferences, or managing a group 

  work organization skills 

A team may be unable for some reason to fund, find, or hire staff to provide the necessary 
specialist skills considered appropriate. Section 4.5.6, Extension of Staff, discusses 
possibilities for addressing such situations. Section 4.5.4, Training Staff, highlights other 
means to build upon and maintain strong skills and to support the continuous improvement to 
reflect changes in constituency, technology, service offerings, etc. 

No single set of skills will be applicable for every position on a given team. It will be 
necessary to look at the constituency served and the range of technologies used to determine 
what skills are appropriate for the specific teams composition. Wherever possible, 
individuals with a mix of skills should be hired to ensure that no single team member in the 
organization is indispensable. On the other hand, smaller teams should have at least one 
person experienced in the skills named to ensure such issues are handled in a professional 
way, although this can lead to other problems when such a person leaves the team. While it 
might seem contradictory, it is much simpler to replace even the most experienced team 
member than a person serving as an interface to the sponsoring/funding organization and to 
other teams. 

4.5.2  Hiring Staff 

When considering applicants for a given staff vacancy, it is important to decide in advance 
the hiring process that will be used to identify the most appropriate candidates. Observations 
from operational experience show that even a candidate who appears on the surface to have 
the appropriate skill set still might not be able to cope with the CSIRT working environment. 
In addition, when a crisis arises, some candidates may not have the ability to handle their 
tasks and do the job. It is better for all concerned to submit a candidate to a hiring process 
that is designed to identify candidate strengths and deficiencies. Armed with that information, 
the team can decide if they are able to train the candidate in the specific skills that the 
candidate may need or choose not to hire the candidate. 

Every CSIRT will be bound to specific requirements based on the requirements of their 
parent organization, local and national laws, and culture. However, where possible and 
appropriate, the following steps should be included in any CSIRT hiring process: 

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  pre-interview document check 
  pre-interview telephone screening 
 
 
 

candidate technical presentation 

interviews that cover topics from technical abilities to social skills and team fit 

reference checks, including criminal records, as appropriate 

Depending on specific organizational needs of the parent organization or the constituency, 
more steps such as security clearances and/or background checks may also be necessary or 
required. 

The overall hiring process should be designed to ensure or identify that the candidate has the 
suitable interpersonal skills for the position and has (or can be trained) in the necessary 
technical skills. As many of the team members as possible should have the chance to interact 
with the candidate, whether that be as an interviewer, through a lunch meeting, or as a 
participant at the candidates technical presentation. Additionally it is important that during 
the interview process the CSIRT staff effort involved in the interview process is kept to a 
minimum, yet is used to the maximum effect.63 

The pre-interview document check and telephone screening with the candidate will help to 
ensure that the candidate is worth bringing in for a personal interview. This step can cover 
issues as wide ranging as the candidates general level of interest in computer security to 
obtaining more specific detail on items covered in their resume. But most importantly, this is 
an opportunity to obtain a good impression of the candidates oral communication skills. 

To make the best use of the CSIRT staff interviewing candidates, it is worthwhile deciding in 
advance what particular issues (ranging from technical issues and ethical issues to social 
skills) you would like to gain through the interview process and which existing staff are most 
suited to cover those issues with the candidate. Each of the various interviewers can then 
cover specific topic areas and save any duplication of effort. Interviewer feedback on the 
issues covered can then be consolidated and discussed by the team members. In some cases, 
another approach may be taken: similar topics may be covered by other team members 
involved in the interview processbut from different perspectivesto determine the 
candidates depth or breadth of knowledge about a particular topic and/or point out any 
weaknesses or inaccuracies in the candidates understanding. 

                                                 
63   Michele Crabb, How To Find and Hire Good Technical People, Proceedings of SANS 1996 

Conference, Washington, D.C., May 12-18, 1996; Katherine T. Fithen, Hiring IRT Staff Interview 
Process, 8th Workshop on Computer Security Incident Handling, Forum of Incident Response 
and Security Teams, San Jose, Calif., July 1996. 

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The requirement to have a candidate give a technical presentation provides the CSIRT with 
an opportunity to gauge other technical and interpersonal qualities of the candidate. The team 
can understand how much common sense the candidate has and how the candidate copes 
under somewhat stressful situations. They can quantify other attributes such as general 
presentation skills, attention to detail, technical accuracy, and ability to answer questions on 
the fly. 

Once an individual is hired, of course, there is much more work to be done to integrate them 
into the CSIRT. The hiring part is just the beginning; the new staff member will need to 
undergo training for some period of time (see 4.5.4, Training Staff). Some new staff 
members may be given access only to limited information until appropriate certifications or 
relevant clearances are obtained (government or military clearances, for example). All new 
staff will also, of course, be required to go through some type of training period to acclimate 
them to the CSIRT as well as other specific policies and procedures for the team and/or 
organization. 

4.5.3  Arrival and Exit Procedures 

Due to the sensitive nature of the information handled by a CSIRT, it is important that special 
procedures are in place to handle the arrival of new staff as well as the departure of staff from 
the team. New staff members might be expected to sign CSIRT-specific agreements in 
addition to any standard employee agreements (such as non-disclosures or intellectual 
property rights) required by the parent organization. The CSIRT-specific agreements might 
include issues ranging from information disclosure to network connectivity and media 
interactions. 

change of passwords (both personal and system passwords) 

Prior to the departure of a member of the CSIRT (even if they are simply moving out of the 
team but staying within the same parent organization), exit procedures should be followed 
and would involve actions to be taken by other appropriate CSIRT members (such as a teams 
system administrators). Exit procedures might include 
 
 
 
  debriefing to review her/his past experiences and to collect ideas for improvements 
 

return of any physical security devices and other media (telephone, pagers, backups) 

revocation of keys (both physical and digital) 

exit interview to remind the departing person of responsibilities, which may include 
additional agreement signing 

 

 

an announcement to the constituency and other parties with which the CSIRT regularly 
interacts 

action to be taken with future correspondence (email, postal) addressed to the individual 

CMU/SEI-2003-HB-002 

171 

If a person leaves the team of their own will, it is worthwhile to understand the reason for 
their decision to leave. This might enable the team to recognize circumstances that need 
further attention to avoid similar departure by other team members. 

Example: Due to long periods without job rotation, the person left the team as another 
organization offered a much more interesting job in the area of multimedia security. 

If a team member is fired (terminated), different exit procedures might apply, since there are 
underlying reasons for the decision that affect the trust placed in the employee. This 
procedure might include escorting the person to remove their personal effects (under the 
watchful eye of the CSIRT management), an exit interview with the human resources 
department in the organization, and escorting/moving the terminated employee off the 
premises (this might be handled by the human resources manager, a site security officer, or 
other security official). Changes of passwords and other measures certainly still apply in such 
cases. In particular, if specific items like keys or hardware tokens cannot be collected, 
appropriate contingency plans must be implemented. 

4.5.4  Training Staff 

Staff training is necessary from three perspectives: bringing new staff members up to the 
necessary skill level to undertake their work; broadening the abilities of existing staff 
members for personal development and overall team benefit; and keeping the overall CSIRT 
skill set up-to-date with emerging technologies and intruder trends. 

When looking at the overall training needs of a team, it is important to identify the overall 
skills needed for each team member, as well as the general skill coverage required for the 
team as a whole. New staff members should be trained immediately in any mandatory skills 
required to make them effective as soon as possible. From a broader perspective, the team 
should be evaluated as a whole to identify training that will expand or increase coverage of 
skill sets in the team and that at the same time addresses a given individuals skill set. 
Policies and procedures should be in place to cover at least initial training and to ensure 
ongoing training as policies and procedures change. Sometimes a refresher course is 
necessary to maintain a steady awareness as to why it is important to follow the established 
policies and procedures, as well as to exercise situations in which personnel must apply their 
own common sense if a gap in the policies and/or procedures is identified. 

In addition to the interpersonal and technical skills discussed earlier in this section, it will be 
important for every member of the team to be trained in areas specific to the incident 
handling functions and the local team environment. Training should include coverage of the 
following issues: 

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local team policies and procedures 

  new technical developments 
 
  understanding and identifying intruder techniques 
 
 
  maintenance of incident records 
 
  work load distribution and organizational techniques 

team building 

communicating with sites 

incident analysis 

Initial training is strongly related to on-the-job-training and deserves further discussion. 
Initial training in many professions is generally in the form of background reading, 
observation, and then learning by experience. This holds true for incident handling, but there 
is no formal educational path for CSIRT staff and limited documentation in the literature, and 
most written material comes in the form of workshop reports or presentation slides. Since the 
written material through which people can learn to handle incidents is limited, on-the-job-
training becomes a necessity.  

The CSIRT Development Team is working to address this gap in available CSIRT training 
and has developed and expanded a suite of training courses and other supporting materials 
that can help train new (or existing) incident handling staff. These training materials target 
managers and technical personnel in areas such as creating and managing CSIRTs, 
responding to and analyzing security incidents, and improving network security [CERT/CC 
2002a]. 

It is also important for new CSIRT staff to review and study internal documents, such as 
policies and procedures, case studies, or past incident summaries that have been archived by 
the team.  

Even the most experienced staff members feel some level of stress when dealing with 
sensitive information. Some of that stress results from their understanding of the magnitude 
of the consequences if they handle the information inappropriately. New staff can be 
overwhelmed with the sheer volume of information, policies, and procedures that they 
encounter in a CSIRT. As a rule, it is inappropriate to submit such new staff to tasks where 
they might inadvertently disclose sensitive information without some initial training. Try to 
ensure that the trainee can learn the profession without making costly mistakes. A commonly 
used approach is one where existing CSIRT staff mentor new staff in the teams policies and 
procedures through on-the-job training. A new staff member might gain proficiency in the 
areas of triage and request handling before moving on to small-scale incidents. In each area, 
the approach could take the form of the new staff member first observing the actions of an 
experienced staff member and undertaking follow-up discussion to address any areas of 

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173 

confusion. Then as they become more familiar with the environment, the new staff member 
drafts email for review and edit by an experienced team member. In this way, progression can 
be made until the new staff member is suitably proficient and considered able to handle such 
tasks without assistance. 

Other approaches prior to dealing with real-life incidents, such as role-playing games, might 
be appropriate and show the new member how policies and procedures affect the handling 
process [Smith 1994].64 

On-the-job training can also be used for existing team members who need to be trained to 
maintain their knowledge base. This is vital for the team, since the technical world is 
changing rapidly. In addition, attending conferences, technical exchanges, brown-bag 
lunches, and/or work in appropriate international task forces and working groups provides 
knowledge not only to the team member involved, but to the team as a whole, when such 
knowledge is shared across the team. 

4.5.5  Retaining Staff 

As discussed in the introduction of this document, experienced CSIRT staff are in short 
supply and expensive to hire and train for your CSIRT environment. So having invested in 
the time and resources to identify, hire, and train staff, it is most important to try to retain 
them. The two main reasons for turnover of CSIRT staff are burnout and low salary. 

Many CSIRT staff suffer from burnout (the authors of this handbook are not exceptions), 
where the constant pressures and stress from daily (and often nightly, if a 24-hour service is 
offered) incident handling tasks become a burden and intrude into the private life. Staff can 
become bored with routine incidents, are physically tired, lack attention to detail, and make 
costly mistakes. Large salaries are now becoming available in the incident response world, 
mostly by way of fee-for-service CSIRTs. But not all teams, especially in the research and 
education community, will have the budget to pay a competitive salary. On the other hand 
these teams do not necessarily provide 24-hour coverage. The pull of large salaries will 
inevitably be enough to immediately draw certain people, but for others, incentives such as 
job satisfaction and personal growth possibilities will encourage them to stay. The following 
approaches should be considered to address both of these issues: 
 
  no more than 80 percent of any individuals effort dedicated to incident handling service 

rotation of duties related to routine work and incident handling 

                                                 
64   Longstaff, Thomas A. Incident Role Playing: An Exercise to Develop New Insights Into the 
Process of Investigating a Computer Security Incident. 5th Workshop on Computer Security 
Incident Handling, Forum of Incident Response and Security Teams, St. Louis, Mo., August 1993. 

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attendance at technical conferences/workshops/tutorials (such as the FIRST 
Conference)65 or other security venues that are applicable (e.g., training courses) 

  participation at technical working groups (like the IETF) 
  development of in-house training courses 
 

attendance at in-house training courses 

Teams that have the greatest success in retaining quality staff have strong team environments 
where staff mix socially as well as in the work environment. They are also organizations in 
which the contributions of all team members (technical and non-technical, new and 
experienced) are considered and valued. 

4.5.6  Extension of Staff 

A team may be unable (for some reason) to find, fund, train, or hire appropriate staff to 
provide the necessary specialist skills required by the team. In such cases, the team can 
consider developing relationships (and clear agreements of understanding) with experts in the 
field to provide the necessary skills. When a situation arises where in-house expertise is 
insufficient, these experts can be called upon to fill the void. Because workload in the CSIRT 
environment is unpredictable and often driven by external events that are not under the 
control of the CSIRT, there are times when existing CSIRT staff will be insufficient to cope 
with the level of demand for its services. It may be appropriate for the CSIRT to have 
procedures in place to reach out for assistance to individuals previously identified as backup 
or extensions to the core CSIRT staff. This will enable the team to cope when the incident 
load peaks above given thresholds, or in other circumstances defined in the teams escalation 
policies and procedures. These additional staffing resources might be drawn from 
  other areas of the security teams in the CSIRT parent organization 
  other groups in the CSIRT parent organization 
  other groups in the CSIRTs constituency 
  other CSIRT organizations 
 

external trusted experts and service providers 

When considering staff to serve in this role, the same hiring principles should apply for them 
as for any CSIRT member. Also, the following processes should be established in advance so 
extension staff can be activated as quickly as possible: 
 
  non-disclosure agreements, service level agreements, memoranda of understanding, etc. 
  up-to-date contact information 

agreed-on criteria for calling in extension staff participation 

                                                 
65   http://www.first.org/conference/ 

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  prior agreements from management 
  procedures to establish secure communications 
 

initial and regular training 

It is essential to provide extension staff on-the-job-training before they are allowed to 
participate in the actual incident handling process. This will give all personnel the chance to 
socialize with each other and become familiar with the way policies and procedures are 
executed through the day. 

 

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5  Closing Remarks 

5.1  Closing Remarks from the First Edition 

Writing this document took much longer than expected and required a considerable amount 
of effort. It wasnt always easy to decide when to provide more detail and when not to. What 
started out to be a short report soon took on a life of its own. Finally we decided that a 
handbook would be a more appropriate term for this document. 

One issue that we struggled with continually was how useful the information would be to 
someone implementing a CSIRT for their own environment and how to provide information 
that would still be applicable a year or more from now. As is true for security in general, the 
needs of each CSIRT are unique and the CSIRT environment is dynamic. There is no chance 
of long-term stability, since technology, the constituency base, and the intruder community 
can change any time. To ensure successful operation, a CSIRT must have the ability to adapt 
to the changing needs of the environment and exhibit the flexibility to deal with the 
unexpected. In addition, a CSIRT must simultaneously address funding issues and 
organizational changes that can affect its ability to either adapt to the needs or provide the 
service itself. 

Throughout the years that we have worked in and influenced the area of CSIRTs and incident 
handling, we have found it rewarding work (despite being hard, sometimes frustrating and 
demanding work). The rewards come from believing in the work, getting the chance to 
interact with other dedicated members of teams from around the world, experiencing the 
willingness of the CSIRT community to share lessons learned and support each other, and 
having a general interest in the work and the underlying technology that supports it. 

One of the main motivations for writing this document is to help others. Collectively, we 
have helped many teams across the world to form, and we learned a lot, made new friends, 
and had fun in the process. But we wanted to document as much of the information that wed 
learned as possible so that others can benefit from it. We hope that we have succeeded in not 
only documenting the information, but also providing it in a form that is both meaningful and 
useful for others. The area of CSIRT development, practices, and processes is still in its 
infancy, and it is still struggling to find its place within the computer security realmwhich 
in turn is finding its niche in the computing arena. We hope that this document will be seen as 
a major contribution to the continued development and maturity of CSIRTs and this field. If 
not, we hope that it can at least be a starting point for further discussion, refinements, 

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improvements, and initiatives to develop better documents, policies, and perhaps standards. 
We will be happy to be involved with or contribute to other efforts of this nature. 

5.2  Closing Remarks for the Second Edition 

Near the latter half of 2002, the CERT CSIRT Development Team decided that it was time to 
take another look at the content in the CSIRT Handbook with a view towards publishing a 
second version that incorporated updated information and lessons learned since the first 
version was published in 1998.  

The updates were undertaken by the CSIRT Development Team (CDT), which is part of the 
Networked Systems Survivability Program (where the CERT/CC is also housed) at the 
Software Engineering Institute in Pittsburgh, PA. Since the first hotline call that was handled 
in 1988, CERT staff have been handling incident reports, learning, and transitioning 
knowledge to others. Early in CERT/CC history, staff developed training materials to assist 
the U.S. Armys Land Information Warfare Activity in building their incident handling 
capability. From that time, training has been an important component of the activities in the 
CERT/CC. In 1996, the idea of a CSIRT Development Team germinated and grew from 
within the incident handling team of the CERT/CC, and this team was formalized as a 
separate component. Our CDT mission is focused primarily on the development of CSIRTs 
world-wide. We achieve this through training courses, direct customer relationships, and 
developing products that provide awareness, education, training, and knowledge in the area 
of computer security incident response. The CDT has trained hundreds of technical and 
management staff to provide them with the knowledge and skills they will need to build their 
own CSIRT. 

Being a part of a world-class organization such as the CERT/CC has taught us new things, 
stretched our minds, and broadened our vision to reach out to othersand to return to the 
community the lessons that have collectively been experienced after nearly 15 years of 
operation. It has provided each of us with an opportunity to meet new friends, share 
experiences, work with other leaders in the CSIRT community, and interact with other 
dedicated members of CSIRTs throughout the world. 

There is a growing consensus that having a CSIRT with the ability to detect attacks and 
incidents, as well as initiating appropriate responses, is expected in many of todays 
organizations. In fact, for some sectors there are mandates or regulations that require an 
organization to have an incident response capability in place. In this regard CSIRTs that are 
part of an enterprise are seen as a partner that is integrated with their risk and security 
management infrastructure. CSIRTs that are supporting large constituencies of independent 
organizations are seen as support centers that provide a variety of benefits to the communities 
being servedthrough support for incident handling (response, notification, education, 
training, awareness) and as dependable links between and across organizations affected by 

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threats, attacks, and computer security incidents. In addition, the protection of critical 
infrastructures is becoming more important today than ever before, and organizations that 
have robust CSIRTs in place with well-defined incident handling processes, as well as related 
management processes, will be able to quickly and effectively respond to threats and attacks 
when they occur.  

Other things have changed over the years as well. In 1998, the original authors stated that 
the area of CSIRTs is still in its infancy; in 2003, we recognize that, in many ways, CSIRTs 
are still the pioneers in developing and promoting a number of incident handling and 
management practices. 

CSIRTs can serve an important role in supporting best practices for management of risk and 
security issues in the technologies that our society relies on today. By incorporating feedback 
and lessons learnedfrom knowledge gained in responding to incidents, vulnerabilities, and 
attacksCSIRTs can help improve security quality management processes for the long-term 
security efforts across the enterprise. In our collective view, it would be fair to say that the 
CSIRT has an established role and place within the computer security realm. New interest in 
the work of such teams results from the need to analyze what actually happened during an 
attack or incident, understand the threats and risks, implement effective responses, and 
prevent future attacks. Computer forensics is an area that is also becoming more important in 
the CSIRT environment and could be seen as a natural progression for additional services that 
CSIRTs might provide to their constituency (and in fact are already being offered by some 
teams). 

Reading through the original handbook and working on the revisions has shown us that we 
remain as passionate about the work, find it rewarding, and want to help others. At the same 
time, we see that the same demands and frustrations that Moira, Don, and Peter experienced 
when they wrote the first handbook still exist today. These past four years have reaffirmed for 
the CSIRT Development Team that the rewards come from believing in the work and seeing 
new teams forming around the globe. 

In closing, the CSIRT Development Team would like to paraphrase the original authors 
words from 1998: We hope that this document will be seen as a major contribution to the 
continued development and maturity of CSIRTs. The original CSIRT Handbook has been 
widely used as a starting point for new teams, as an evaluating and benchmarking tool by 
existing teams, and as a mechanism to suggest further refinements, improvements, and 
initiatives to develop even better policies, processes, procedures, and standards of practice in 
this area. 

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179 

Finally, we believe strongly that this new release, together with other documents the CSIRT 
Development Team will publish,66 will further add to the body of knowledge and support in 
this important area of activity. Each CSIRT environment is a little different from the next and 
each has something to add to the overall knowledge we seek. The importance of sharing 
lessons learned, the exchange of ideas, experiences, and processes with other new or existing 
teams can have a tremendous effect on raising the bar on CSIRT activities. We have 
knowledge about a large number of teams that exist (through our own interactions and 
discussions with individuals in FIRST and TERENA), but we suspect that there are many 
additional teams being created that we have not yet heard about. If you have established a 
CSIRT, wed like to hear from you.  

We welcome your comments on this handbook. If you want to share your opinions or have 
suggested additions (or other comments) to this handbook, please contact us. We regularly 
attend FIRST conferences, and we can be contacted in person or reached as a group by 
sending email to csirt-handbook@cert.org. 

                                                 
66   For example, the State of the Practice of CSIRTs, Organizational Models for CSIRTs, and other 

CSIRT-related publications that will appear on our Web site at http://www.cert.org/csirts/. 

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Appendix A:  About the Authors 

The authors of this handbook have extensive experience in the formation, documentation, and 
operation of their own teams incident handling services and in assisting many different 
computer security incident response teams (CSIRTs) around the world from their inception 
through formation and operation. The authors are leading figures in the CSIRT community. 
They are frequently invited to give presentations on a wide range of Internet security topics, 
from critical infrastructure issues to social impact. 

Moira J. West-Brown <moira@west-brown.com> 

Moira J. West-Brown was a senior member of the technical staff within the CERT 
Coordination Center (CERT/CC) based at the Software Engineering Institute (SEI) until 
1999. Prior to leaving the SEI, West-Brown led the group responsible for facilitating and 
assisting the formation of new CSIRTs around the globe. This group assisted a wide range of 
different organizations in the formation of national, government, Internet service provider, 
and academic CSIRTs. 

West-Brown joined the CERT/CC in 1991 as a technical coordinator, responding to computer 
security incidents and vulnerability reports. For several years she managed the CERT 
Operations team, which focuses on reactive tasks aimed at responding to computer security 
attacks and vulnerabilities. She successfully led the team through a period of dramatic 
increase in the rate of intruder reports, and she established and developed many of the 
operational standards adopted for use by other CSIRTs today. 

Prior to her tenure in the CERT/CC, West-Brown had extensive experience in system 
administration, software development, and user support/liaison, which was gained at a variety 
of companies ranging from academic institutions and industrial software consultancies to 
government-funded research programs. 

West-Brown has been an active figure in the international CSIRT community. She developed 
a variety of tutorial and workshop materials focusing mainly on operational and collaborative 
CSIRT issues. She was elected to the FIRST Steering Committee in 1995 and served as the 
Steering Committee Chair from 1997 to 1999. 

West-Brown holds a first-class bachelors degree in Computational Science from the 
University of Hull, U.K. 

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Klaus-Peter Kossakowski <kpk@presecure.de> 

Klaus-Peter Kossakowski is managing director of an independent German company 
providing senior consultancy on International Information Infrastructure, IT security and 
Incident Response since early 2000. Kossakowskis work currently involves risk and security 
management, incident response services, public key infrastructures, intrusion detection, 
network security, forensics, and security improvement. 

Kossakowski has worked in the security field for more than 15 years. In 1988 he was one of 
the first members of the Virus Test Center in Hamburg, where he focused on malicious 
network programs. He was involved with DFN-CERT (the first German CSIRT for an open 
network) from its inception. From January 1993 until he left DFN-CERT at the end of 1997, 
he managed the DFN-CERT team, which was modeled after the CERT/CC. He successfully 
led the team from a research effort to a functional and well-respected entity in the CSIRT 
community. From 1998 to 1999 he was a senior consultant and project manager at secunet 
Security Networks AG, a German IT security provider, where he founded the internal secu-
CERT team. He was also a visiting scientist at the CERT/CC from 1998 to 2003. 
Kossakowski continues his collaborative efforts with the CSIRT Development Team to 
develop technical articles, documents, training materials, and other CSIRT-related 
publications. 

Kossakowskis particular interests in the CSIRT arena are international issues, cooperation, 
and establishing a CSIRT infrastructure. As the co-chair of the IETF working group 
Guidelines and Recommendations for Incident Processing (GRIP), he has been involved 
with the development of several RFCs since 1994. Together with Don Stikvoort, he initiated a 
closer cooperation among European CSIRTs and organized several annual meetings to 
support these. His vocal role in the European CSIRT community resulted in him becoming 
chair for a TERENA task force called CERTs in Europe. This task force outlined the 
concept and service definition of a European CSIRT Coordination Center. As a result of this 
effort, EuroCERT was implemented in late 1996. He was elected as a member of the Forum 
of Incident Response and Security Teams (FIRST) Steering Committee in 1997 and re-
elected in 1999 and 2001. In this role he actively supports international CSIRT cooperation 
and the move of FIRST toward a new organizational structure. 

Kossakowski has defended his doctoral thesis in Information TechnologyIncident 
Response Capabilities at the University of Hamburg. He holds a first-class degree in 
Information Science from the University of Hamburg. Kossakowski is a member of the 
Internet Society (ISOC), the Information Systems Security Association (ISSA), and the 
German Gesellschaft fuer Informatik e. V. (GI). 

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Don Stikvoort <don@elsinore.nl> 

Don Stikvoort is managing director and co-founder of the Dutch companies STELVIO and  
S-CURE, offering senior consultancy services in the areas of Internet and intranet security. 

He has worked in the security area for more than 15 years. After his academic years he 
embarked on his working life as Infantry platoon commander in the Dutch Army. He joined 
SURFnet, the Dutch national research and educational network, in 1989. During his 9 years 
at SURFnet, Stikvoort had a variety of responsibilities. He started out as consultant but soon 
became responsible for setting up the SURFnet backbone. Later he managed subcontractors 
responsible for the SURFnet Helpdesk and other user-oriented services, and led several 
development projects. He was involved in the formation of CERT-NL in 1991 and was its 
chairman from 1992 to 1998. 

Stikvoort is an active participant internationally in RIPE, TERENA, IETF, and the FIRST 
community, particularly in regard to security issues. Together with Klaus-Peter Kossakowski, 
he initiated the closer cooperation of European CSIRTs in 1993 and has contributed since that 
time to efforts leading to a more structured European incident coordination. From 1996 to 
1998 he was actively involved in helping FIRST to evolve its organizational structure and 
funding model. In 1998 he finished the first version of the Handbook for Computer Security 
Incident Response Teams (CSIRTs) together with Klaus-Peter Kossakowski and Moira J. 
West-Brown. Stikvoort was chairman of the Program Committee for the 1999 FIRST 
conference in Brisbane, Australia. 

Stikvoort holds a degree in experimental low temperature physics from Leiden University, 
The Netherlands. He is a member of ISOC and participates in several national security fora. 
He is end-responsible for the operation of the international FIRST secretariat and the 
European Trusted Introducer service (which offers an independent accreditation process for 
European CSIRTs), both of which are subcontracted to S-CURE. Recently Stikvoort has been 
engaged in consultancy on behalf of kennisnet, the national Dutch school network, and on 
behalf of the Dutch Government GOVCERT.NL . He currently participates in the set-up and 
execution of several CSIRT courses, and is the coordinator of eCSIRT.net, an EU-funded 
research project that aims at implementing the IODEF standard for exchange of incident data 
and statistics between CSIRTs. 

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183 

Georgia Killcrece <georgia@cert.org> 
Georgia Killcrece is a member of the technical staff in the CERT CSIRT Development 
Team, part of the Networked Systems Survivability (NSS) Program based at the Software 
Engineering Institute (SEI) at Carnegie Mellon University in Pittsburgh, Pennsylvania.  
Killcrece joined the CERT Coordination Center (CERT/CC) in September of 1989, just 10 
months after the CERT/CC was formally established. 

Killcrece has worked directly with a variety of organizations (government, industry, and 
academia) across various stages of their CSIRT development: education/training, planning, 
implementation, operation, collaboration. She is also involved in the development and 
delivery of public and onsite training courses, and is one of a few instructors at the Software 
Engineering Institute who regularly teaches the suite of five CSIRT courses. At the end of 
2002, Killcrece and her team completed a program to license the CSIRT training materials. 
Through transition partners licensed to deliver the CSIRT courses, CSIRT training can now 
be disseminated to a much broader global community. Jointly, the team has published 
documents currently available on the CERT Web site (http://www.cert.org/csirts/), to extend 
the availability of information to organizations establishing their own CSIRT. 

Prior to becoming leader of the CERT CSIRT Development Team, Killcrece was a technical 
coordinator and incident response coordinator in the CERT Coordination Center from 1994 to 
1999. In those roles, she gained first-hand knowledge of the processes involved in forming, 
operating, and evolving incident response teams, including the dynamics of working in a fast-
paced team environment. Her primary responsibilities included handling computer security 
compromises and vulnerability reports. As a part-time member of the Information Services 
team in the Networked Systems Survivability program, Killcrece also contributed to the 
development and maintenance of CERT/CC materials published on the CERT Web site. 

Killcrece is a co-author or contributor to papers and reports relating to computer security 
incident response teams, including Creating a Computer Security Incident Response 
Team: A Process for Getting Started, CSIRT Services, CSIRT Frequently Asked 
Questions, and this revised edition of the Handbook for Computer Security Incident 
Response Teams(CSIRTs). Other publications include Organizational Models for CSIRTs and 
State of the Practice of Computer Security Incident Response Teams, scheduled for release in 
2003.  

She can be reached directly by email at georgia@cert.org or via the CSIRT training alias 
at csirt-info@cert.org. 

184 

 

CMU/SEI-2003-HB-002 

Robin Ruefle <rmr@cert.org> 

Robin Ruefle is a member of the technical staff in the CERT CSIRT Development Team, part 
of the Practices, Development, and Training group in the Networked Systems Survivability 
program at the SEI. 

Ruefles focus is on the development of management, procedural, and technical guidelines 
and practices for the establishment, maturation, and operation of CSIRTs worldwide. Ruefle 
develops and delivers sessions in the suite of courses offered to CSIRT managers and incident 
handling staff, including Creating a CSIRT, Managing CSIRTs, Fundamentals of Incident 
Handling, and Advanced Incident Handling for Technical Staff. She also participates in the 
Train-the-Trainer program that licenses these products to existing CSIRTs. As a member of 
the CERT CSIRT Development Team she provides guidance in the development of 
implementation strategies, policies, standard operating procedures, response plans, and 
training programs for new and existing CSIRTs. Ruefle is a co-author or contributor to papers 
and reports relating to computer security incident response teams, including Creating a 
Computer Security Incident Response Team: A Process for Getting Started, CSIRT Services, 
and CSIRT Frequently Asked Questions.  

Prior to coming to the SEI, Ruefle worked as a consultant and trainer in the Academic 
Computing department at the University of Pittsburgh. During her time with Academic 
Computing she managed the academic computing public labs, training program, and 
consulting office. She also served as project leader for the wireless laptop pilot program and 
Microsoft Windows NT conversion project. Before that, she developed database programs, 
training courses, and documentation for the Central Services Comptrollers office in the 
Office of the Budget of the Commonwealth of Pennsylvania. 

Ruefle received a BS in political science and a Master of Public and International Affairs 
from the University of Pittsburgh. She is also an adjunct faculty member in the MBA 
program at Chatham College and the Graduate School of Public and International Affairs at 
the University of Pittsburgh, where she teaches courses in information technology, 
management information systems, and information retrieval and analysis. 

She can be reached directly by email at rmr@cert.org or via the CSIRT training alias at csirt-
info@cert.org. 

 

 

CMU/SEI-2003-HB-002 

185 

Mark Zajicek <mtz@cert.org> 

Mark Zajicek is a member of the technical staff at the Software Engineering Institute (SEI) at 
Carnegie Mellon University. 

Zajiceks current work is focused on helping other organizations to build their own computer 
security incident response teams (CSIRTs). As a member of the CERT CSIRT Development 
Team <http://www.cert.org/csirts/>, part of the Practices, Development, and Training group 
in the Networked Systems Survivability program at the SEI, he is responsible for providing 
guidance to new and existing CSIRTs worldwide. He has co-developed a variety of 
documents and training materials, and is an instructor for a suite of courses that provide 
training for CSIRT managers and technical staff. 

Previously, Zajicek was the Daily Operations team leader for the CERT Coordination Center 
(CERT/CC), after having joined the CERT/CCs incident handling staff in 1992. Prior to 
joining the CERT/CC, he was a user consultant for the Computing Facilities group at the SEI. 
Zajicek also helped support the CERT/CC during its initial start-up in 1988. 

Zajicek holds a bachelors degree in Electrical Engineering and Biomedical Engineering from 
Carnegie Mellon University 

 

186 

 

CMU/SEI-2003-HB-002 

Appendix B:  Glossary 

This glossary lists acronyms and abbreviations that are used throughout the handbook and 
contains a short list of definitions of the most important terms relevant to the objectives of the 
handbook. 

Acronyms and Abbreviations 
24x7 

twenty-four hours a day, seven days a week 

AFS 

BCERT 

CERT/CC 

CERT-NL 

CIDR 

CIRC 

CIRT 

CSIRC 

CSIRT 

CSRC 

Andrew file system 

Boeing CERT 

CERT Coordination Center 

Computer Emergency Response Team Netherlands 

Classless Inter-Domain Routing 

Computer Incident Response Capability 

Computer Incident Response Team 

Computer Security Incident Response Capability 

Computer Security Incident Response Team 

Computer Security Resource Center 

DFN-CERT 

Deutsches Forschungsnetz Computer Emergency Response Team 

DNS 

FIRST 

FTP 

GPG 

GRIP 

HTTP 

ICMP 

IETF 

IHT 

INND 

Domain Name System 

Forum of Incident Response and Security Teams 

file transfer protocol 

Gnu Privacy Guard 

Guidelines and Recommendations for Incident Processing 

Hypertext Transmission Protocol 

Internet Control Message Protocol 

Internet Engineering Task Force 

Incident Handling Team 

Internet news daemon 

CMU/SEI-2003-HB-002 

187 

IP 

IRC 

IRT 

ISP 

Internet protocol 

Incident Response Team 

incident response team 

Internet service provider 

MCERT 

Motorola Computer Emergency Response Team 

MD5 

MIME 

NTP 

PGP 

POC 

RFC 

Message Digest 5 

Multipurpose Internet Messaging Extension 

Network Time Protocol 

Pretty Good Privacy 

point of contact 

request for comments 

S/MIME 

Secure Multipurpose Internet Mail Exchange 

SERT 

SIRT 

SMTP 

SSC 

SSH 

STE 

STU III 

SUNSeT 

TCP 

TERENA 

TTP 

UBC 

UCE 

UDP 

UNI-CERT 

WWW 

 

Security Emergency Response Team 

Security Incident Response Team 

Simple Mail Transport Protocol 

site security contact 

Secure Shell 

Secure Terminal Equipment 

Secure Telecommunication Unit III 

Stanford University Network Security Team 

Transmission Control Protocol 

Trans-European Research and Education Networking Association 

trusted third party 

Unsolicited Bulk E-Mail 

Unsolicited Commercial E-mail 

User Datagram Protocol 

Unisource Business Networks Computer Emergency Response 
Team 

World Wide Web 

188 

 

CMU/SEI-2003-HB-002 

Terms 

Artifact 

The remnants of an intruder attack or incident activity. These could be software used by 
intruder(s), a collection of tools, malicious code, logs, files, output from tools, status of a 
system after an attack or intrusion. Examples of artifacts range from Trojan-horse programs 
and computer viruses to programs that exploit (or check for the existence of) vulnerabilities 
or objects of unknown type and purpose found on a compromised host. 

Authenticity 

If the identity of some subject or object can be checked and verified, the relationship between 
the subject/object and its identity is called authentic. In the realm of computer security this is 
usually associated with verifying that information which is sent or received has not been 
altered in any way during transmission. 

Bugtraq 

A mailing list for the discussion of security problems and vulnerabilities. Occasionally full 
disclosure reports of new vulnerabilities and exploit tools are distributed through this list. 

Computer Security Incident 

Any real or suspected adverse event in relation to the security of computer systems or 
computer networks. Examples of such events are 
 
 
  probes for vulnerabilities via the network to a range of computer systems (often referred 

intrusion of computer systems via the network (often referred to as hacking) 

the occurrence of computer viruses 

to as scans) 

In the computer security arena, these events are often simply referred to as incidents. 

Computer Security Incident Handling 

By providing the basic set of services (triage, handling, and request), a team offers a defined 
constituency support for responding to computer security incidents. In addition to this basic 
set, an announcement service might also be offered. 

CSIRT 

An acronym for computer security incident response team. This is a team providing 
services to a defined constituency. There are several acronyms used to describe teams 

CMU/SEI-2003-HB-002 

189 

providing similar types of services (e.g., CSIRC, CSRC, CIRC, CIRT, IHT, IRC, IRT, SERT, 
SIRT). We have chosen to use the generic term CSIRT, as it has been widely adopted in the 
computer security community.  

Depending on factors such as expertise and resources, the level and range of service provided 
might be different for various teams.  

Constituency 

A specific group of people and/or organizations that have access to specific services offered 
by a CSIRT. 

Intruder 

A person who is the perpetrator of a computer security incident. Intruders are often referred 
to as hackers or crackers. While hackers were very technical experts in the early days 
of computing, this term was later used by the media to refer to people who break into other 
computer systems. Crackers is based on hackers and the fact that these people crack 
computer systems and security barriers. Most of the time cracker is used to refer to more 
notorious intruders and computer criminals. Sometimes it is argued that the term attacker 
would be better, as an unsuccessful attack doesnt constitute an intrusion. But because of the 
intention of the person responsible for the attack, the term intruder is used throughout this 
document. 

Liability 

The responsibility of someone for damage or loss. 

Policy 

A set of written statements directing the operation of an organization or community in regard 
to specific topics such as security or dealing with the media. 

Procedure 

The implementation of a policy in the form of workflows, orders, or mechanisms. 

Remnant Files 

Files left by intruders on compromised systems. These can range from Ethernet sniffer log 
files, password files, exploit scripts, and source code to various programs (may also be called 
artifacts). 

190 

 

CMU/SEI-2003-HB-002 

Security Policy 

A policy addressing security issues. 

Site 

Depending on the context in which this term is used, it might apply to computer system(s) 
that are grouped together by geographical location, organizational jurisdiction, or network 
addresses. 

Site Security Contact (SSC) 

A person responsible for computer security issues at a specific site. 

Social Engineering 

Social engineering is the art and science of getting people to do something you want them to 
do that they might not do in the normal course of action.  

Instead of collecting information by technical means, intruders might also apply methods of 
social engineering such impersonating individuals on the telephone, or using other persuasive 
means (e.g., tricking, convincing, inducing, enticing, provoking) to encourage someone to 
disclose information. Since these are based on the social interactions and habits of people, it 
is called social engineering. 

Triage 

The process of receiving, initial sorting, and prioritizing of information to facilitate its 
appropriate handling. 

Trojan Horse 

A normally trustworthy program or process modified to include unwanted and unknown 
functions that may (or can) compromise the security of the user, system, network, 
application, or protocol involved. 

Vulnerability 

The existence of a software weakness, such as a design or implementation error, that can lead 
to an unexpected, undesirable event compromising the security of a system, network, 
application, or protocol. 

CMU/SEI-2003-HB-002 

191 

 

192 

 

CMU/SEI-2003-HB-002 

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194 

 

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[CERT/CC 2002b] 

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[Kossakowski 2001]  Kossakowski, Klaus-Peter. Information Technology Incident  

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CMU/SEI-2003-HB-002 

199 

 
 

200 

 

CMU/SEI-2003-HB-002 

 

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4. 

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Handbook for Computer Security Incident Response Teams (CSIRTs) 

5. 

FUNDING NUMBERS 
F19628-00-C-0003 

6.  AUTHOR(S) 

Moira West-Brown, Don Stikvoort, Klaus-Peter Kossakowski, Georgia Killcrece, Robin Ruefle, Mark Zajicek 

7.  PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

Software Engineering Institute 
Carnegie Mellon University 
Pittsburgh, PA 15213 

9.  SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 

HQ ESC/XPK 
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CMU/SEI-2003-HB-002 

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12B  DISTRIBUTION CODE 

 

This document provides guidance on forming and operating a computer security incident response team 
(CSIRT). In particular, it helps an organization to define and document the nature and scope of a computer 
security incident handling service, which is the core service of a CSIRT. The document explains the functions 
that make up the service; how those functions interrelate; and the tools, procedures, and roles necessary to 
implement the service. This document also describes how CSIRTs interact with other organizations and how 
to handle sensitive information. In addition, operational and technical issues are covered, such as equipment, 
security, and staffing considerations. 

This document is intended to provide a valuable resource to both newly forming teams and existing teams 
whose services, policies, and procedures are not clearly defined or documented. The primary audience for 
this document is managers who are responsible for the creation or operation of a CSIRT or an incident 
handling service. It can also be used as a reference for all CSIRT staff, higher level managers, and others 
who interact with a CSIRT. 

14.  SUBJECT TERMS 

computer security incident response team, incident handling, incident 
response, CSIRT, incident response service, team operations, 
information handling, continuity assurance, security management, risk 
management 

15.  NUMBER OF PAGES 

222 

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19.  SECURITY CLASSIFICATION OF 

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