Risk Assessment Tools and Practices
for Information System Security
The purpose of this paper is to provide financial institutions and examiners with
background information and guidance on various risk assessment tools and practices related
to information security. Institutions using the Internet or other computer networks are
exposed to various categories of risk that could result in the possibility of financial
loss and reputational harm. Given the rapid growth of the Internet and networking
technology, the available risk assessment tools and practices are becoming more important
for information security.
This paper provides a summary of critical points, discusses components of a sound
information security program, and describes the risk assessment and risk management
processes for information security. The appendix provides specific information on certain
risk assessment tools and practices that may be part of an institution's information
security program. The paper and appendix are intended to provide useful information and
guidance, not to create new examination standards, impose new regulatory requirements, or
represent an exclusive description of the various ways financial institutions can
implement effective information security programs.
Whether financial institutions contract with third-party providers1
for computer services such as Internet banking, or maintain computer services in-house,
bank management is responsible for ensuring that systems and data are protected against
risks associated with emerging technologies and computer networks. If a bank is relying on
a third-party provider, management must generally understand the provider's information
security program to effectively evaluate the security system's ability to protect bank and
The FDIC has previously issued guidance on information security concerns such as data
privacy and confidentiality, data integrity, authentication, non-repudiation, and access
control/system design. This paper is designed to supplement Financial Institution Letter
131-97, "Security Risks Associated With the Internet," dated December 18, 1997,
and to complement the FDIC's safety and soundness electronic banking examination
procedures. Related guidance can be found in the FFIEC Information Systems Examination
To ensure the security of information systems and data, financial institutions should
have a sound information security program that identifies, measures, monitors, and manages
potential risk exposure. Fundamental to an effective information security program is
ongoing risk assessment of threats and vulnerabilities surrounding networked and/or
Internet systems. Institutions should consider the various measures available to support
and enhance information security programs. The appendix to this paper describes certain
vulnerability assessment tools and intrusion detection methods that can be useful in
preventing and identifying attempted external break-ins or internal misuse of information
systems. Institutions should also consider plans for responding to an information security
A financial institution's board of directors and senior management should be aware of
information security issues and be involved in developing an appropriate information
security program. A comprehensive information security policy should outline a proactive
and ongoing program incorporating three components:
Prevention measures include sound security policies, well-designed system
architecture, properly configured firewalls, and strong authentication programs. This
paper discusses two additional prevention measures: vulnerability assessment tools and
penetration analyses. Vulnerability assessment tools generally involve running scans on a
system to proactively detect known vulnerabilities such as security flaws and bugs in
software and hardware. These tools can also detect holes allowing unauthorized access to a
network, or insiders to misuse the system. Penetration analysis involves an independent
party (internal or external) testing an institution's information system security to
identify (and possibly exploit) vulnerabilities in the system and surrounding processes.
Using vulnerability assessment tools and performing regular penetration analyses will
assist an institution in determining what security weaknesses exist in its information
Detection measures involve analyzing available information to determine if an
information system has been compromised, misused, or accessed by unauthorized individuals.
Detection measures may be enhanced by the use of intrusion detection systems (IDSs) that
act as a burglar alarm, alerting the bank or service provider to potential external
break-ins or internal misuse of the system(s) being monitored.
Another key area involves preparing a response program to handle suspected
intrusions and system misuse once they are detected. Institutions should have an effective
incident response program outlined in a security policy that prioritizes incidents,
discusses appropriate responses to incidents, and establishes reporting requirements.
The appendix provides a detailed discussion on prevention (vulnerability assessment
tools and penetration analyses), detection (IDS tools), and response measures. Before
implementing some or all of these measures, an institution should perform an information
security risk assessment. Depending on the risk assessment, certain risk assessment tools
and practices discussed in this paper may be appropriate. However, use of these measures
should not result in decreased emphasis on information security or the need for human
A thorough and proactive risk assessment is the first step in establishing a sound
security program. This is the ongoing process of evaluating threats and vulnerabilities,
and establishing an appropriate risk management program to mitigate potential monetary
losses and harm to an institution's reputation. Threats have the potential to harm an
institution, while vulnerabilities are weaknesses that can be exploited.
The extent of the information security program should be commensurate with the degree
of risk associated with the institution's systems, networks, and information assets. For
example, compared to an information-only Web site, institutions offering transactional
Internet banking activities are exposed to greater risks. Further, real-time funds
transfers generally pose greater risks than delayed or batch-processed transactions
because the items are processed immediately. The extent to which an institution contracts
with third-party vendors will also affect the nature of the risk assessment program.
Performing a sound risk assessment is critical to establishing an effective information
security program. The risk assessment provides a framework for establishing policy
guidelines and identifying the risk assessment tools and practices that may be appropriate
for an institution. Banks still should have a written information security policy, sound
security policy guidelines, and well-designed system architecture, as well as provide for
physical security, employee education, and testing, as part of an effective program.
When institutions contract with third-party providers for information system services,
they should have a sound oversight program. At a minimum, the security-related clauses of
a written contract should define the responsibilities of both parties with respect to data
confidentiality, system security, and notification procedures in the event of data or
system compromise. The institution needs to conduct a sufficient analysis of the
provider's security program, including how the provider uses available risk assessment
tools and practices. Institutions also should obtain copies of independent penetration
tests run against the provider's system.
When assessing information security products, management should be aware that many
products offer a combination of risk assessment features, and can cover single or multiple
operating systems. Several organizations provide independent assessments and
certifications of the adequacy of computer security products (e.g., firewalls). While the
underlying product may be certified, banks should realize that the manner in which the
products are configured and ultimately used is an integral part of the products'
effectiveness. If relying on the certification, banks should understand the certification
process used by the organization certifying the security product. Other examples of items
to consider in the risk assessment process include:
Identifying mission-critical information systems, and determining the effectiveness of
current information security programs. For example, a vulnerability might involve
critical systems that are not reasonably isolated from the Internet and external access
via modem. Having up-to-date inventory listings of hardware and software, as well as
system topologies, is important in this process.
Assessing the importance and sensitivity of information, and the likelihood of outside
break-ins (e.g., by hackers) and insider misuse of information. For example, if a
large depositor list were made public, that disclosure could expose the bank to
reputational risk and the potential loss of deposits. Further, the institution could be
harmed if human resource data (e.g., salaries and personnel FILes) were made public. The
assessment should identify systems that allow the transfer of funds, other assets, or
sensitive data/confidential information, and review the appropriateness of access controls
and other security policy settings.
Assessing the risks posed by electronic connections with business partners. The
other entity may have poor access controls that could potentially lead to an indirect
compromise of the bank's system. Another example involves vendors that may be allowed to
access the bank's system without proper security safeguards, such as firewalls. This could
result in open access to critical information that the vendor may have "no need to
Determining legal implications and contingent liability concerns associated with any of
the above. For example, if hackers successfully access a bank's system and use it to
subsequently attack others, the bank may be liable for damages incurred by the party that
Serious hackers, interested computer novices, dishonest vendors or competitors,
disgruntled current or former employees, organized crime, or even agents of espionage pose
a potential threat to an institution's computer security. The Internet provides a wealth
of information to banks and hackers alike on known security flaws in hardware and
software. Using almost any search engine, average Internet users can quickly find
information describing how to break into various systems by exploiting known security
flaws and software bugs. Hackers also may breach security by misusing vulnerability
assessment tools to probe network systems, then exploiting any identified weaknesses to
gain unauthorized access to a system. Internal misuse of information systems remains an
ever-present security threat.
Many break-ins or insider misuses of information occur due to poor security programs.
Hackers often exploit well-known weaknesses and security defects in operating systems that
have not been appropriately addressed by the institution. Inadequate maintenance and
improper system design may also allow hackers to exploit a security system. New security
risks arise from evolving attack methods or newly detected holes and bugs in existing
software and hardware. Also, new risks may be introduced as systems are altered or
upgraded, or through the improper setup of available security-related tools. An
institution needs to stay abreast of new security threats and vulnerabilities. It is
equally important to keep up to date on the latest security patches and version upgrades
that are available to fix security flaws and bugs. Information security and relevant
vendor Web sites contain much of this information.
Systems can be vulnerable to a variety of threats, including the misuse or theft of
passwords. Hackers may use password cracking programs to figure out poorly selected
passwords. The passwords may then be used to access other parts of the system. By
monitoring network traffic, unauthorized users can easily steal unencrypted passwords. The
theft of passwords is more difficult if they are encrypted. Employees or hackers may also
attempt to compromise system administrator access (root access), tamper with critical
FILes, read confidential e-mail, or initiate unauthorized e-mails or transactions.
Hackers may use "social engineering," a scheme using social techniques to
obtain technical information required to access a system. A hacker may claim to be someone
authorized to access the system such as an employee or a certain vendor or contractor. The
hacker may then attempt to get a real employee to reveal user names or passwords, or even
set up new computer accounts. Another threat involves the practice of "war
dialing," in which hackers use a program that automatically dials telephone numbers
and searches for modem lines that bypass network firewalls and other security measures. A
few other common forms of system attack include:
Denial of service (system failure), which is any action preventing a system from
operating as intended. It may be the unauthorized destruction, modification, or delay of
service. For example, in a "SYN Flood" attack, a system can be flooded with
requests to establish a connection, leaving the system with more open connections than it
can support. Then, legitimate users of the system being attacked are not allowed to
connect until the open connections are closed or can time out.
Internet Protocol (IP) spoofing, which allows an intruder via the Internet to
effectively impersonate a local system's IP address in an attempt to gain access to that
system. If other local systems perform session authentication based on a connection's IP
address, those systems may misinterpret incoming connections from the intruder as
originating from a local trusted host and not require a password.
Trojan horses, which are programs that contain additional (hidden) functions that
usually allow malicious or unintended activities. A Trojan horse program generally
performs unintended functions that may include replacing programs, or collecting,
falsifying, or destroying data. Trojan horses can be attached to e-mails and may create a
"back door" that allows unrestricted access to a system. The programs may
automatically exclude logging and other information that would allow the intruder to be
Viruses, which are computer programs that may be embedded in other code and can
self-replicate. Once active, they may take unwanted and unexpected actions that can result
in either nondestructive or destructive outcomes in the host computer programs. The virus
program may also move into multiple platforms, data files, or devices on a system and
spread through multiple systems in a network. Virus programs may be contained in an e-mail
attachment and become active when the attachment is opened.
It is important for financial institutions to develop and implement appropriate
information security programs. Whether systems are maintained in-house or by third-party
vendors, appropriate security controls and risk management techniques must be employed. A
security program includes effective security policies and system architecture, which may
be supported by the risk assessment tools and practices discussed in this guidance paper
and appendix. Information security threats and vulnerabilities, as well as their
countermeasures, will continue to evolve. As such, institutions should have a proactive
risk assessment process that identifies emerging threats and vulnerabilities to
A sound information security policy identifies prevention, detection, and response
measures. The appendix provides more details on risk assessment tools and practices that
may be used to improve information security programs. Preventive measures may include
regularly using vulnerability assessment tools and conducting periodic penetration
analyses. Intrusion detection tools can be effective in detecting potential intrusions or
system misuse. Institutions should also develop a response program to effectively handle
any information security breaches that may occur.
1 For the purposes of this paper, "third-party
provider" is broadly defined. Third-party providers include entities that may provide
the following services or products to institutions: system design, development,
administration, and maintenance services; data processing services; and hardware and/or
Vulnerability assessment tools, also called security scanning tools, assess the
security of network or host systems and report system vulnerabilities. These tools can
scan networks, servers, firewalls, routers, and applications for vulnerabilities.
Generally, the tools can detect known security flaws or bugs in software and hardware,
determine if the systems are susceptible to known attacks and exploits, and search for
system vulnerabilities such as settings contrary to established security policies.
In evaluating a vulnerability assessment tool, management should consider how
frequently the tool is updated to include the detection of any new weaknesses such as
security flaws and bugs. If there is a time delay before a system patch is made available
to correct an identified weakness, mitigating controls may be needed until the system
patch is issued.
Generally, vulnerability assessment tools are not run in real-time, but they are
commonly run on a periodic basis. When using the tools, it is important to ensure that the
results from the scan are secure and only provided to authorized parties. The tools can
generate both technical and management reports, including text, charts, and graphs. The
vulnerability assessment reports can tell a user what weaknesses exist and how to fix
them. Some tools can automatically fix vulnerabilities after detection.
As in intrusion detection systems, which are discussed later in this appendix, there
are generally two types of vulnerability assessment tools: host-based and network-based.
Another category is sometimes used for products that assess vulnerabilities of specific
applications (application-based) on a host. A host is generally a single computer or
workstation that can be connected to a computer network. Host-based tools assess the
vulnerabilities of specific hosts. They usually reside on servers, but can be placed on
specific desktop computers, routers, or even firewalls. Network-based vulnerability
assessment tools generally reside on the network, specifically analyzing the network to
determine if it is vulnerable to known attacks. Both host- and network-based products
offer valuable features, and the risk assessment process should help an institution
determine which is best for its needs. Information systems personnel should understand the
types of tools available, how they operate, where they are located, and the output
generated from the tools.
Host-based vulnerability assessment tools are effective at identifying security risks
that result from internal misuse or hackers using a compromised system. They can detect
holes that would allow access to a system such as unauthorized modems, easily guessed
passwords, and unchanged vendor default passwords. The tools can detect system
vulnerabilities such as poor virus protection capabilities; identify hosts that are
configured improperly; and provide basic information such as user log-on hours,
password/account expiration settings, and users with dial-in access. The tools may also
provide a periodic check to confirm that various security policies are being followed. For
instance, they can check user permissions to access FILes and directories, and identify
FILes and directories without ownership.
Network-based vulnerability assessment tools are more effective than host-based at
detecting network attacks such as denial of service and Internet Protocol (IP) spoofing.
Network tools can detect unauthorized systems on a network or insecure connections to
business partners. Running a host-based scan does not consume network overhead, but can
consume processing time and available storage on the host. Conversely, frequently running
a network-based scan as part of daily operations increases network traffic during the
scan. This may cause inadvertent network problems such as router crashes.
After the initial risk assessment is completed, management may determine that a
penetration analysis (test) should be conducted. For the purpose of this paper,
"penetration analysis" is broadly defined. Bank management should determine the
scope and objectives of the analysis. The scope can range from a specific test of a
particular information system's security or a review of multiple information security
processes in an institution.
A penetration analysis usually involves a team of experts who identify an information
system's vulnerability to a series of attacks. The evaluators may attempt to circumvent
the security features of a system by exploiting the identified vulnerabilities. Similar to
running vulnerability scanning tools, the objective of a penetration analysis is to locate
system vulnerabilities so that appropriate corrective steps can be taken.
The analysis can apply to any institution with a network, but becomes more important if
system access is allowed via an external connection such as the Internet. The analysis
should be independent and may be conducted by a trusted third party, qualified internal
audit team, or a combination of both. The information security policy should address the
frequency and scope of the analysis. In determining the scope of the analysis, items to
consider include internal vs. external threats, systems to include in the test, testing
methods, and system architectures.
A penetration analysis is a snapshot of the security at a point in time and does not
provide a complete guaranty that the system(s) being tested is secure. It can test the
effectiveness of security controls and preparedness measures. Depending on the scope of
the analysis, the evaluators may work under the same constraints applied to ordinary
internal or external users. Conversely, the evaluators may use all system design and
implementation documentation. It is common for the evaluators to be given just the IP
address of the
institution and any other public information, such as a listing of officers that is
normally available to outside hackers. The evaluators may use vulnerability assessment
tools, and employ some of the attack methods discussed in this paper such as social
engineering and war dialing. After completing the agreed-upon analysis, the evaluators
should provide the institution a detailed written report. The report should identify
vulnerabilities, prioritize weaknesses, and provide recommendations for corrective action.
A penetration analysis itself can introduce new risks to an institution; therefore,
several items should be considered before having an analysis completed, including the
If using outside testers, the reputation of the firm or consultants hired. The
evaluators will assess the weaknesses in the bank's information security system. As such,
the confidentiality of results and bank data is crucial. Just like screening potential
employees prior to their hire, banks should carefully screen firms, consultants, and
subcontractors who are entrusted with access to sensitive data. A bank may want to require
security clearance checks on the evaluators. An institution should ask if the evaluators
have liability insurance in case something goes wrong during the test. The bank should
enter into a written contact with the evaluators, which at a minimum should address the
If using internal testers, the independence of the testers from system administrators.
The secrecy of the test. Some senior executives may order an analysis without the
knowledge of information systems personnel. This can create unwanted results, including
the notification of law enforcement personnel and wasted resources responding to an
attack. To prevent excessive responses to the attacks, bank management may consider
informing certain individuals in the organization of the penetration analysis.
The importance of the systems to be tested. Some systems may be too critical to be
exposed to some of the methods used by the evaluators such as a critical database that
could be damaged during the test.
PART TWO DETECTION: Discusses intrusion detection systems, and using these tools
as the detection component of an institution's information security program.
Vulnerability assessments and penetration analyses help ensure that appropriate
security precautions have been implemented and that system security configurations are
appropriate. The next step is to monitor the system for intrusions and unusual activities.
Intrusion detection systems (IDSs) may be useful because they act as a burglar alarm,
reporting potential intrusions to appropriate personnel. By analyzing the information
generated by the systems being guarded, IDSs help determine if necessary safeguards are in
place and are protecting the system as intended. In addition, they can be configured to
automatically respond to intrusions.
Computer system components or applications can generate detailed, lengthy logs or audit
trails that system administrators can manually review for unusual events. IDSs automate
the review of logs and audit data, which increases the review's overall efficiency by
reducing costs and the time and level of skill necessary to review the logs.
Typically, there are three components to an IDS. First is an agent, which is the
component that actually collects the information. Second is a manager, which processes the
information collected by the agents. Third is a console, which allows authorized
information systems personnel to remotely install and upgrade agents, define intrusion
detection scenarios across agents, and track intrusions as they occur. Depending on the
complexity of the IDS, there can be multiple agent and manager components.
Generally, IDS products use three different methods to detect intrusions. First, they
can look for identified attack signatures, which are streams or patterns of data
previously identified as an attack. Second, they can look for system misuse such as
unauthorized attempts to access FILes or disallowed traffic inside the firewall. Third,
they can look for activities that are different from the user's or system's normal
pattern. These "anomaly-based" products (which use artificial intelligence) are
designed to detect subtle changes or new attack patterns, and then notify appropriate
personnel that an intrusion may be occurring. Some anomaly-based products are created to
update normal use patterns on a regular basis. Poorly designed anomaly-based products can
trigger frequent false-positive responses.
Although IDSs may be an integral part of an institution's overall system security, they
will not protect a system from previously unknown threats or vulnerabilities. They are not
self-sufficient and do not compensate for weak authentication procedures (e.g., when an
intruder already knows a password to access the system). Also, IDSs often have overlapping
features with other security products, such as firewalls. IDSs provide additional
protections by helping to determine if the firewall programs are working properly and by
helping to detect internal abuses. Both firewalls and IDSs need to be properly configured
and updated to combat new types of attacks. In addition, management should be aware that
the state of these products is highly dynamic and IDS capabilities are evolving.
IDS tools can generate both technical and management reports, including text, charts,
and graphs. The IDS reports can provide background information on the type of attack and
recommend courses of action. When an intrusion is detected, the IDS can automatically
begin to collect additional information on the attacker, which may be needed later for
As with vulnerability assessment tools, there are generally two types of IDS products:
host-based and network-based. A third product category is sometimes used for IDSs that
look for unusual application events (application-based) on a host. Both network- and
host-based tools offer valuable features, and the risk assessment process should help
institutions determine if either, or a combination of both, is best for their needs.
Host-based IDSs are also known as audit trail analysis tools or server-based IDSs
(often placed on servers). A host-based IDS will look for potential intrusions or patterns
of misuse by monitoring host event activities, audit logs, and other security-related
activities. The tools will track audit trails from operating systems, applications, Web
servers, routers, and firewalls, as well as monitor critical FILes for Trojan horses and
unauthorized changes. This can provide valuable evidence of a break-in and can assist in
assessing damage because the intruder's actions are logged on the specific hosts. If done
in real-time, the IDS can promptly notify the bank of unauthorized attempts to gain system
administrator (root) controls, access or change critical files, or replace log-in
An important benefit of host-based IDSs is that they are effective in detecting insider
misuse because they monitor activities on the specific hosts. For example, they can
monitor a user's attempt to access a restricted file, or an attempt to execute a system
administrator's command. In addition, they can monitor encrypted transmissions as the data
is generally decrypted before it is logged at the host.
A problem with host-based systems is that notification of the attack is delayed if an
agent does not examine the audit trail in real-time. This problem relates to the
relatively large consumption of computer processing speed and disk space that is required
to run these programs in real-time. If not run in real-time, they still allow a bank to
identify larger trends and problems with system security.
With network-based IDSs, software or sniffers are placed on one or multiple points
across the network. The sniffer agent analyzes packets of information moving across the
network for potential intrusions. Network packets contain data, including the message and
headers that identify the sending and receiving parties. Network-based IDSs look for
patterns of misuse, specific types of attacks, and unusual activity such as unexpected
volume and types of network traffic. Compared to host-based IDSs, certain types of
network-orientated attacks such as IP spoofing, packet floods, and denial of service, are
best detected through packet examination.
Network-based IDSs can detect potential intrusions in real-time, and offer concurrent
notification and response capabilities to potential intrusions. The software does not need
to be put on the various hosts throughout the network, thus it is generally easier to
monitor and may be less expensive than host-based IDSs.
Network-based IDSs sometimes mistakenly identify normal traffic as an intrusion
("false positives") and vice versa ("false negatives"). They can have
difficulties detecting slow attacks and experience problems with busy networks.
Network-based IDSs cannot monitor encrypted transmissions (only detect that data is being
transferred across the network), and are less effective at detecting insider misuse
because network packet analysis does not monitor the activities on specific hosts.
Once it is determined that an IDS is necessary to detect possible security breaches,
several factors should be considered in evaluating IDSs, including:
The comprehensiveness of the attack signature database, including the frequency of
updates that incorporate newly identified concerns. Most products rely on vendor
updates, so banks need to assess the timeliness of the IDS vendor's updates. Products can
be updated through Internet downloads, CD-ROM or floppy disk updates, or even manually if
the user has a sufficient degree of technical knowledge.
The effectiveness of the IDS in protecting an institution from both internal and
external threats to a computer system. The IDS should limit the number of false
positives (incorrectly identifying an attack when none has occurred) and false negatives
(not identifying an attack when one has occurred).
The impact on performance of the network and/or host(s). Generally, IDSs work on a
real-time basis. Real-time analysis provides quicker notification of potential intrusions;
however, it can reduce system performance due to the additional memory and processing
requirements. Non-real-time analysis generally consumes fewer resources, but has the
disadvantage that the potential intrusion has already occurred. Knowledgeable intruders,
moreover, can manipulate audit trails, making the after-the-fact analysis useless in
detecting these particular intruders.
The security of the IDS itself and how secure the update process is, especially if
The reporting and automated response capabilities. IDSs will sometimes generate more
information than can be reviewed by present qualified staff. Also, for privacy
reasons, management should consider informing all affected system users about the scope
and type of monitoring being conducted.
Other things to consider include training and support from the vendor, cost of
hardware, software, and maintenance agreements, integration with vulnerability assessment
tools, and configuration capabilities.
An institution's risk assessment process should first determine whether an IDS is
necessary. Next, the type or placement of an IDS depends on the priority of identified
threats or vulnerabilities. If one or a few hosts contain information that management
views as critical, a host-based IDS may be warranted. If the information is less
essential, other controls such as a firewall and/or filtering routers may be sufficient to
protect the information. If an institution is primarily concerned with attacks from the
outside or views the entire network system as critical, a network-based product may be
appropriate. A combination of host- and network-based IDSs may also be appropriate for
effective system security. Management should be aware that even after an IDS is in place,
there may be other access points to the bank's systems that are not being monitored.
Management should determine what types of security precautions are needed for the other
The placement of the IDS within the institution's system architecture should be
carefully considered. The primary benefit of placing an IDS inside a firewall is the
detection of attacks that penetrate the firewall as well as insider abuses. The primary
benefit of placing an IDS outside of a firewall is the ability to detect such activities
as sweeping, which can be the first sign of attack; repeated failed log-in attempts; and
attempted denial of service and spoofing attacks. Placing an IDS outside the firewall will
also allow the monitoring of traffic that the firewall stops.
PART THREE RESPONSE: Discusses implementing an incident response strategy for
the response component of an institution's information security program.
After implementing a defense strategy and monitoring for new attacks, hacker
activities, and unauthorized insider access, management should develop a response
strategy. The sophistication of an incident response plan will vary depending on the risks
inherent in each system deployed and the resources available to an institution. In
developing a response strategy or plan, management should consider the following:
The plan should provide a platform from which an institution can prepare for, address,
and respond to intrusions or unauthorized activity. The beginning point is to assess the
systems at risk, as identified in the overall risk assessment, and consider the potential
types of security incidents.
The plan should identify what constitutes a break-in or system misuse, and incidents
should be prioritized by the seriousness of the attack or system misuse.
Individuals should be appointed and empowered with the latitude and authority to respond
to an incident. The plan should include what the appropriate responses may be for
potential intrusions or system misuses.
A recovery plan should be established, and in some cases, an incident response team
should be identified.
The plan should include procedures to officially report the incidents to senior
management, the board of directors, legal counsel, and law enforcement agents as
Today's products not only can detect intrusions in real-time, but can automatically
respond to intrusions. Depending on the software, information systems personnel can be
notified on a real-time basis during an attack, rather than detect the attack afterward
during a manual log review. Methods of notification can include e-mail, pager, fax, audio
alarm, or message displays on a computer monitor. Responses can include shutting down the
system, logging additional information, and disabling a user's account (e.g., by
disallowing a particular user account or Internet address). Access can be disabled for a
period sufficient for information systems personnel to review the attack information or
verify the user. Also, an institution can add warning banners to protected systems,
notifying users that they are accessing a protected computer system.
When determining an appropriate response, a distinction should be made between
incidents in which actual changes to a system are suspected (e.g., changing audit logs)
versus incidents in which system misuse is suspected (e.g., unauthorized system access).
Attempts to actually change the system or data may warrant notifying a security officer,
who could reconfigure the identified weaknesses and/or communication paths. An appropriate
response to system misuse may include automatic log-off, warning messages, or notifying
the appropriate personnel.
Not only are attacks often undetected, in many cases identified attacks are not
reported. Institutions should develop a plan to respond to unauthorized activities and
involve law enforcement when appropriate. Institutions should report suspected computer
crimes and computer intrusions on Suspicious Activity Reports (SARs) in accordance with
the guidelines outlined in Financial Institution Letter 124-97, "Suspicious Activity
Reporting," dated December 5, 1997.