Establishing a Computer Security Incident Response Capability

Establishing a Computer Security Incident Response Capability

Advising users on computer systems technology
February 1992

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Copyright(c), 1996 - Management Analytics and Others - All Rights Reserved


Computer systems and the information they store are valuable resources that need to be protected. Increasingly sophisticated threats including system and network intruders, computer viruses, and network worms can exploit a variety of weaknesses in computer systems and cause significant damage. Due to increased use of local area networks (LANs) and large networks such as the Internet, damage caused by seemingly isolated computer security incidents can spread to other systems, causing widespread denial of service and other losses.

Government agencies, business, and academic institutions need to take steps to understand the increased threats now affecting computer systems and to learn how to respond to computer security incidents with the requisite speed and skill. This bulletin recommends the use of a Computer Security Incident Response Capability (CSIRC) as part of a computer security program so that incidents can be contained and ultimately prevented in a timely and cost-effective manner.

A Changing Threat Scenario

Prior to the mid 1980s, the predominate threats to computer security (besides errors and omissions) were physical and environmental, including insider attacks, fire and water damage, theft, and physical damage. The threats are largely understood and controllable through the use of traditional controls and contingency planning. Now, a new class of software-based threats has become as important to understand and control; these threats include unauthorized intruders and users who exploit system vulnerabilities, computer viruses, network worms, and Trojan horses. Several factors have contributed to the growing presence of these threats.

Reliance on Computers - Many agencies rely on computers and networks for communications and accomplishment of work; con-versely, many agencies would suffer great losses to produc-tivity should their systems become unavailable. Due to system complexity, reliance on computer systems often pres-ents unanticipated risks and vulnerabilities.

Computer Viruses - Computer viruses in particular have caused a major upheaval in personal computer security. Some virus researchers believe that the virus problem is getting worse, due in part to the proliferation of personal computers (with minimal built-in security controls), LANs, and a disregard for safe computing practices. The number of variants of viruses has also increased, pushing the total number of viruses close to one thousand or more. Some researchers estimate that the probability of a personal computer user encountering a virus has increased substantially.

Use of Large Networks - Large networks, linking governments, businesses, and academia, are growing by leaps and bounds. Efficient response to computer security incidents is very important for agencies positioned on large networks, as com-promise of one computer can affect a significant number of other systems connected to the network but located in differ-ent organizations, with resultant legal and financial ramifications. Incident response teams note that intruder attempts to penetrate systems occur daily at numerous sites throughout the United States, and that many agencies are often unaware that their systems have been penetrated or used as springboards for attacks on other systems.

How Bad is the Problem? - Computer security incidents appear regularly in media reports. In 1988, the Internet Worm caused shutdowns and denial of service problems for weeks to over 3000 sites. In 1989, the NASA WANK (Worms Against Nu-clear Killers) Worm caused a major loss of availability along two large government networks, resulting in significant expense and investigations by the GAO into network manage-ment and security. Other incidents include intruders using international networks to target to U.S. government systems. There are also reports of virus-infected software being shipped by vendors and distributors, and reports of viruses on LAN servers that spread throughout entire organizations in minutes. While publicized incidents tell us that the computer security picture is not good, most computer security incidents are never reported.

The CSIRC Concept

Many computer security programs are not effective in dealing with this newer and less-understood class of threats. Traditional responses, such as risk analysis, contingency planning, and computer security reviews, have not been sufficient in controlling incidents and preventing significant damage. Stories abound of incidents in which the problems grow worse or do not go away. Fearing unknown threats, some have misguidedly restricted their access to systems and networks. Consequently, some organizations spend far too much time reacting to recurring incidents at costs to convenience and productivity. What is needed, therefore, is a fundamentally different form of computer security response that is capable of quickly detecting and responding to incidents in a manner that is both cost-efficient and effective.

A Computer Security Incident Response Capability (CSIRC) is prepared to detect and react to computer security incidents in a skilled and efficient manner. A CSIRC is a combination of technically skilled people, policies, and techniques that constitute a proactive approach to handling computer security incidents. A CSIRC, with traditional computer security elements, can provide organization-wide protection from damaging incidents, saving the organization valuable resources and permitting it to take better advantage of computer technology. Already, a number of agencies and other institutions have started CSIRC efforts, with good success.

Skilled and Efficient Response - Skill and efficiency are the hallmarks of a CSIRC. Without a CSIRC, incident response can be disorganized and ineffective, with much higher expenses and vulnerabilities still left open and unprotected. For example, uneducated responses to small outbreaks of computer viruses can actually make the problems far worse, resulting in hundreds of computers being infected by the response team itself. A CSIRC will help to manage incident response expenses that otherwise would be difficult to track, to make risk assessment more accurate, and to improve user training and awareness of computer security. Conversely, an inefficient incident response effort could perpetuate exist-ing problems and even make them worse.

Centralization and Non-Duplication of Effort - A CSIRC utilizes centralized means for reporting and handling inci-dents. This increases efficiency; however, it also permits more accurate assessment of incidents, such as whether they are related (to more quickly avert possible widespread damage). By virtue of centralization, CSIRC expenses and overhead can be held down and duplication of effort can be reduced or possibly eliminated. Agencies may find that a significant cost savings can result.

Enhanced User Awareness of Threats - The benefits of a CSIRC include enhanced user awareness of threats and knowledge of appropriate controls. A CSIRC will identify vulnerabilities, issue computer security alerts, and make contacts with other computer security groups, all resulting in increased information that can be made available to the organization through a variety of mechanisms: electronic bulletin boards, networks, seminars, and training workshops. This information will greatly improve users' ability to manage their systems efficiently and securely.

Building a CSIRC

Many computer security programs will not need to build a CSIRC "from the ground up." Rather, they may already have a number of the building blocks necessary, such as help desks, central hotlines, and personnel with the requisite technical skills. Constituency - Implicit in the concept of a CSIRC is the requirement for a constituency, i.e., those users served by the CSIRC. In many cases, the constituency will be the organization itself. The size and scope of a CSIRC, however, are directly impacted by the needs and size of the constitu-ency, including its degree of technical knowledge, the diversity of technologies, and the sensitivity of the systems and data.

CSIRC Structure - There is no "one" structure for a CSIRC; depending on an agency's needs and structure, a CSIRC can take many forms. A highly centralized CSIRC may represent the most cost-effective structure; however, some agencies may find that a more distributed structure, with some inevitable overlap, will fit in best with existing agency structures. Very small agencies and organizations may find it practical to share a CSIRC with a larger organization. Hence, a CSIRC structure will vary depending on many factors. Centralized reporting and centralization of effort will help to decrease operating costs and at the same time improve efficiency and security.

Centralized Reporting - Effective incident response depends upon the constituency's ability to quickly and conveniently communicate with the CSIRC. Effective communications mechanisms include a central telephone "hotline" monitored on a 24-hour basis, a central electronic-mail (e-mail) address, or a pager arrangement. Users should be encouraged to contact the CSIRC by making the communications straightforward (i.e., having to remember only one telephone number).

Alert Mechanisms - The constituency will be best served if there is also a convenient mechanism for the CSIRC to alert the constituency. The CSIRC should be able to quickly reach all users by sending to a central mailing list or, alternatively, telephone voice mailbox messages or management points-of-contact lists.

Personnel - CSIRC personnel will need to diagnose or understand technical problems, thus technical knowledge is a primary qualification. Good communications skills are equally important. Computer security incidents can foster emotionally charged situations; hence a skilled communicator must know how to resolve technical problems without fueling emotions or adding complications. In addition, CSIRC personnel may spend much of their time communicating with affected users and managers, either directly or by p reparing alert information, bulletins, and other guidance. It may be difficult to find personnel who have the correct mix of tech-nical, communications, and political skills.

Contracting a CSIRC

When contracting, agencies should keep in mind that numerous sensitive issues can arise from incident handling; these issues will be very important to consider in any contractual agreement. Because a CSIRC may play a large role in determining computer security policy, agencies may find it advantageous to contract certain tasks associated with a CSIRC as opposed to contracting the entire CSIRC operation.

Agencies should expect that increased communications and oversight will be necessary when contracting any part of a CSIRC and that some incident response expertise will have to be developed in-house for this purpose. The agency and contractor will need to coordinate closely on many issues, including dealings with the media, vendors, legal and investigative matters, and dealings with outside groups (especially if involved in a mutual incident). The sensi-tivity of data or operations may require contractor personnel to get security clearances; handling classified informa-tion by contractors may require increased oversight.

Importance of Traditional Computer Security


An incident response capability does not do away with the need for effective risk analysis, physical security, and other standard components of a computer security program. Simple errors and omissions may still remain the primary threat to computer security, along with other physical and environmental threats; they should not be ignored or downplayed in light of the attention often given to viruses and related threats. A strong risk analysis program remains highly important for identifying the complete set of threats, vulnerabilities, and controls; the logs and statistics gathered by a CSIRC will help to make subsequent risk analyses more precise and useful. Computer security reviews are still a preferred method for improving the security program, of which a CSIRC is just one component.

Cooperation Among CSIRCs

System intruders, viruses, and similar threats do not respect organizational boundaries. It follows, then, that cooperation among CSIRCs can be valuable for learning about current threats, sharing incident response-related information, and resolving incidents. Additionally, cooperating CSIRCs may be able to assist each other in situations where one CSIRC possesses certain technical skills that another CSIRC lacks.

The Forum of Incident Response and Security Teams - The Forum of Incident Response and Security Teams (FIRST) is a group of incident response teams whose members work together voluntarily to deal with computer security problems and their prevention. The objective of FIRST is to further communications among CSIRCs and to foster increased participation in incident response-related activities.

There are two types of participation in the forum. Forum Members, i.e., incident response teams, assist a defined constituency in preventing and handling computer security-related incidents. Liaisons are individuals or representatives of organizations other than emergency response teams that have a legitimate interest in and value to the forum. Several U.S. agencies participate, as well as industry and academia.

NIST Special Publication 800-3

NIST Special Publication (SP) 800-3, Establishing a Computer Security Incident Response Capability (CSIRC), provides more information on issues in establishing and operating a CSIRC, including an annotated bibliography of incident response-related documents. This guide can be obtained from the Government Printing Office (GPO), Washington, DC 20402, GPO Stock Number SN003-003-03121-6, for $3.00. An electronic version of SP 800-3 in PostScript format can be obtained from our Computer Security BBS or via the Internet using ftp or e-mail. Information about FIRST is also available, including membership information, operational procedures, and incident response team contact information.