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Security Guidance
Responding to IT Security Incidents
Security Policy and Operations On This Page
Introduction
Balanced Scorecard for Before You Begin
Information Security Introduction Minimizing the Number and Severity of Security Incidents
IT Infrastructure Threat Modeling Assembling the Core Computer Security Incident Response Team
Guide Defining an Incident Response Plan
Responding to IT Security Containing the Damage and Minimizing the Risks
Incidents Related Information
Security Configuration
Recommendations Introduction
How prepared is your information technology (IT) department or administrator to handle security incidents?
Many organizations learn how to respond to security incidents only after suffering attacks. By this time, incidents
often become much more costly than needed. Proper incident response should be an integral part of your
overall security policy and risk mitigation strategy.
There are clearly direct benefits in responding to security incidents. However, there might also be indirect
financial benefits. For example, your insurance company might offer discounts if you can demonstrate that your
organization is able to quickly and cost-effectively handle attacks. Or, if you are a service provider, a formal
incident response plan might help win business, because it shows that you take seriously the process of good
information security.
This document will provide you with a recommended process and procedures to use when responding to
intrusions identified in a small- to medium-based (SMB) network environment. The value of forming a security
incident response team with explicit team member roles is explained, as well as how to define a security incident
response plan.
To successfully respond to incidents, you need to:
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Before You Begin
System administrators spend a lot of time with network environments, and are very familiar with networks. They
document the environments and have backups in place. There should be an auditing process already in place to
monitor performance and utilization. There should be a level of awareness already achieved prior to
implementing an incident response team.
No matter how much detail you know about the network environment, the risk of being attacked remains. Any
sensible security strategy must include details on how to respond to different types of attacks.
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Minimizing the Number and Severity of Security Incidents
In most areas of life, prevention is better than cure, and security is no exception. Wherever possible, you will want
to prevent security incidents from happening in the first place. However, it is impossible to prevent all security
incidents. When a security incident does happen, you will need to ensure that its impact is minimized. To minimize
the number and impact of security incidents, you should:
Clearly establish and enforce all policies and procedures. Many security incidents are accidentally created
by IT personnel who have not followed or not understood change management procedures or have
improperly configured security devices, such as firewalls and authentication systems. Your policies and
procedures should be thoroughly tested to ensure that they are practical and clear and provide the
appropriate level of security.
Gain management support for security policies and incident handling.
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Routinely assess vulnerabilities in your environment. Assessments should be done by a security specialist
with the appropriate clearance to perform these actions i.e. (bondable and given administrator rights to
the systems).
Routinely check all computer systems and network devices to ensure that they have all of the latest patches
installed.
Establish security training programs for both IT staff and end users. The largest vulnerability in any system
is the inexperienced user ? the ILOVEYOU worm effectively exploited that vulnerability among IT staff and
end users.
Post security banners that remind users of their responsibilities and restrictions, along with a warning of
potential prosecution for violation. These banners make it easier to collect evidence and prosecute
attackers. You should obtain legal advice to ensure that the wording of your security banners is
appropriate.
Develop, implement, and enforce a policy requiring strong passwords. You can learn more about
passwords in "Enforcing Strong Password Usage Throughout Your Organization" in the Security Guidance
Kit.
Routinely monitor and analyze network traffic and system performance.
Routinely check all logs and logging mechanisms, including operating system event logs, application
specific logs and intrusion detection system logs.
Verify your back-up and restore procedures. You should be aware of where backups are maintained, who
can access them, and your procedures for data restoration and system recovery. Make sure that you
regularly verify backups and media by selectively restoring data.
Create a Computer Security Incident Response Team (CSIRT) to deal with security incidents. You can learn
more about CSIRT in the following section of this document.
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Assembling the Core Computer Security Incident Response Team
The CSIRT is the focal point for dealing with computer security incidents in your environment. Your team should
consist of a group of people with responsibilities for dealing with any security incident. Team members should
have clearly defined duties to ensure that no area of your response is left uncovered.
Assembling a team before an incident occurs is very important to your organization and will positively influence
how incidents are handled. A successful team will:
When you create a CSIRT, prepare the team so they are equipped to handle incidents. To prepare the team, you
should:
Train them on the proper use and location of critical security tools. You should also consider providing
portable computers that are preconfigured with these tools to ensure that no time is wasted installing and
configuring tools so they can respond to an incident. These systems and the associated tools must be
properly protected when not in use.
Assemble all relevant communication information. You should ensure that you have contact names and
phone numbers for people within your organization who need to be notified (including members of the
CSIRT, those responsible for supporting all of your systems, and those in charge of media relations). You
will also need details for your Internet service provider (ISP) and local and national law enforcement
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will also need details for your Internet service provider (ISP) and local and national law enforcement
agencies. Discuss with your legal counsel about contacting local law enforcement before an incident
happens. This will help you to ensure that you understand proper procedures for communicating incidents
and collecting evidence. Legal counsel should be informed of any contacts with law enforcement.
Place all emergency system information in a central, offline location, such as a physical binder or an offline
computer. This emergency information includes passwords to systems, Internet Protocol (IP) addresses,
router configuration information, firewall rule set lists, copies of certification authority keys, contact names
and phone numbers, escalation procedures, and so on. This information must both be readily available
and be kept extremely physically secure. One method of securing and making this information readily
available is to encrypt it on a dedicated security portable computer that is placed in a secure vault and
limit access to the vault to authorized individuals such as the CSIRT leader and the CIO or CTO.
The ideal CSIRT membership and structure depends on the type of your organization and your risk management
strategy. However, the CSIRT should generally form part or all of your organization's security team. Inside the
core team are security professionals responsible for coordinating a response to any incident. The number of
members in the CSIRT will typically depend on the size and complexity of your organization. However, you should
ensure that there are enough members to adequately cover all of the duties of the team at any time.
Associate
Role Description
Member
IT Contact This member is primarily responsible for coordinating communication between the CSIRT
Incident Lead and the rest of the IT group. The IT Contact might not have the particular
technical expertise to respond to the particular incident; however, he or she will be primarily
responsible for finding people in the IT group to handle particular security events.
Legal This member is a lawyer who is very familiar with established incident response policies. The
Representative Legal Representative determines how to proceed during an incident with minimal legal
liability and maximum ability to prosecute offenders.
Before an incident occurs, the Legal Representative should have input on monitoring and
response policies to ensure that the organization is not being put at legal risk during a
cleanup or containment operation. It is very important to consider the legal implications of
shutting down a system and potentially violating service level agreements or membership
agreements with your customers, or not shutting down a comprised system and being liable
for damages caused by attacks launched from that system.
Any communication to outside law enforcement or external investigative agencies should
also be coordinated with the Legal Representative.
Public Generally, this member is part of the public relations department and is responsible for
Relations protecting and promoting the image of the organization.
Officer
This individual might not be the actual face to the media and customers, but he or she is
responsible for crafting the message (the content and objective of the message is generally
the responsibility of management). All media inquiries should be directed to Public Relations.
Management Depending on the particular incident, you might involve only departmental managers, or you
might involve managers across the entire organization. The appropriate management
individual will vary according to the impact, location, severity, and type of incident.
If you have a managerial point of contact, you can quickly identify the most appropriate
individual for the specific circumstances. Management is responsible for approving and
directing security policy.
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directing security policy.
Management is also responsible for determining the total impact (both financial and
otherwise) of the incident on the organization. Management directs the Communications
Officer regarding which information should be disclosed to the media and determines the
level of interaction between the Legal Representative and law enforcement agencies.
Responding to an Incident
In the event of an incident, the CSIRT will coordinate a response from the core CSIRT and will communicate with
the associate members of the CSIRT. The following table shows the responsibilities of these individuals during the
incident response process.
Responsibilities of CSIRT During the Incident Response Process
Activity Role
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Defining an Incident Response Plan
All members of your IT environment should be aware of what to do in the event of an incident. The CSIRT will
perform most actions in response to an incident, but all levels of your IT staff should be aware of how to report
incidents internally. End users should report suspicious activity to the IT staff directly or through a help desk
rather than directly to the CSIRT.
Every team member should review the incidence response plan in detail. Having the plan easily accessible to all IT
staff will help to ensure that when an incident does occur, the right procedures are followed.
To instigate a successful incident response plan, you should:
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These steps are not purely sequential. Rather, they happen throughout the incident. For example, documentation
starts at the very beginning and continues throughout the entire life cycle of the incident; communication also
happens throughout the entire incident.
Other aspects of the process will work alongside each other. For example, as part of your initial assessment, you
will gain an idea of the general nature of the attack. It is important to use this information to contain the damage
and minimize risk as soon as possible. If you act quickly, you can help to save time and money, and your
organization's reputation.
However, until you understand the type and severity of the compromise in more detail, you will not be able to be
truly effective in containing the damage and minimizing the risk. An overzealous response could even cause more
damage than the initial attack. By working these steps alongside each other, you will get the best compromise
between swift and effective action.
Note: It is very important that you thoroughly test your incident response process before an incident occurs.
Without thorough testing, you cannot be confident that the measures that you have in place will be effective in
responding to incidents.
Take steps to determine whether you are dealing with an actual incident or a false positive.
Gain a general idea of the type and severity of attack. You should gather at least enough information to
begin communicating it for further research and to begin containing the damage and minimizing the risk.
Record your actions thoroughly. These records will later be used for documenting the incident (whether
actual or false).
Note: You should avoid false positives whenever possible; however, it is always better to act on a false positive
than fail to act on a genuine incident. Your initial assessment should, therefore, be as brief as possible, yet still
eliminate obvious false positives.
1. Protect human life and people's safety. This should, of course, always be your first priority.
2. Protect classified and sensitive data. As part of your planning for incident response, you should clearly
define which data is classified and which is sensitive. This will enable you to prioritize your responses in
protecting the data.
3. Protect other data, including proprietary, scientific, and managerial data. Other data in your
environment might still be of great value. You should act to protect the most valuable data first before
moving on to other, less useful, data.
4. Protect hardware and software against attack. This includes protecting against loss or alteration of
system files and physical damage to hardware. Damage to systems can result in costly downtime.
5. Minimize disruption of computing resources (including processes). Although uptime is very important
in most environments, keeping systems up during an attack might result in greater problems later on. For
this reason, minimizing disruption of computing resources should generally be a relatively low priority.
There are a number of measures that you can take to contain the damage and minimize the risk to your
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There are a number of measures that you can take to contain the damage and minimize the risk to your
environment. At a minimum, you should:
Try to avoid letting attackers know that you are aware of their activities. This can be difficult, because some
essential responses might alert attackers. For example, if there is an emergency meeting of the CSIRT, or
you require an immediate change of all passwords, any internal attackers might know that you are aware
of an incident.
Compare the cost of taking the compromised and related systems offline against the risk of continuing
operations. In the vast majority of cases, you should immediately take the system off the network.
However, you might have service agreements in place that require keeping systems available even with the
possibility of further damage occurring. Under these circumstances, you can choose to keep a system
online with limited connectivity in order to gather additional evidence during an ongoing attack.
In some cases, the damage and scope of an incident might be so extensive that you might have to take
action that invokes the penalty clauses specified in your service level agreements. In any case, it is very
important that the actions that you will take in the event of an incident are discussed in advance and
outlined in your response plan so that immediate action can be taken when an attack occurs.
Determine the access point(s) used by the attacker and implement measures to prevent future access.
Measures might include disabling a modem, adding access control entries to a router or firewall, or
increasing physical security measures.
Consider rebuilding a fresh system with new hard disks (the existing hard disks should be removed and
put in storage as these can be used as evidence if you decide to prosecute attackers). Ensure that you
change any local passwords. You should also change administrative and service account passwords
elsewhere in your environment.
Determine the nature of the attack (this might be different than the initial assessment suggests).
Determine the attack point of origin.
Determine the intent of the attack. Was the attack specifically directed at your organization to acquire
specific information, or was it random?
Identify the systems that have been compromised.
Identify the files that have been accessed and determine the sensitivity of those files.
By performing these actions, you will be able to determine the appropriate responses for your environment. A
good incident response plan will outline specific procedures to follow as you learn more about the attack.
Generally, the nature of the attack symptoms will determine the order in which you follow the procedures defined
in your plan. Since time is crucial, less time-consuming procedures should generally be carried out before more
lengthy ones. To help determine the severity of the compromise, you should:
Contact other members of the response team to inform them of your findings, have them verify your
results, determine whether they are aware of related or other potential attack activity, and help identify
whether the incident is a false positive. In some cases, what might appear to be a genuine incident on
initial assessment will prove to be a false positive.
Determine whether unauthorized hardware has been attached to the network or whether there are any
signs of unauthorized access through the compromise of physical security controls.
Examine key groups (domain administrators, administrators, and so on) for unauthorized entries.
Search for security assessment or exploitation software. Cracking utilities are often found on compromised
systems during evidence gathering.
Look for unauthorized processes or applications currently running or set to run using the startup folders
or registry entries.
Search for gaps in, or the absence of, system logs.
Review intrusion detection system logs for signs of intrusion, which systems might have been affected,
methods of attack, time and length of attack, and the overall extent of potential damage.
Examine other log files for unusual connections; security audit failures; unusual security audit successes;
failed logon attempts; attempts to log on to default accounts; activity during nonworking hours; file,
directory, and share permission changes; and elevated or changed user permissions.
Compare systems to previously conducted file/system integrity checks. This enables you to identify
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Compare systems to previously conducted file/system integrity checks. This enables you to identify
additions, deletions, modifications, and permission and control modifications to the file system and
registry. You can save a lot of time when responding to incidents if you identify exactly what has been
compromised and what areas need to be recovered.
Search for sensitive data, such as credit card numbers and employee or customer data, that might have
been moved or hidden for future retrieval or modifications. You might also have to check systems for non-
business data, illegal copies of software, and e-mail or other records that might assist in an investigation.
If there is a possibility of violating privacy or other laws by searching on a system for investigative
purposes, you should contact your legal department before you proceed.
Match the performance of suspected systems against their baseline performance levels. This of course
presupposes that baselines have been created and properly updated.
When determining which systems have been compromised and how, you will generally be comparing your
systems against a previously recorded baseline of the same system before it was compromised. Assuming that a
recent system shadow copy is sufficient for comparison might put you in a difficult situation if the previous
shadow copy comes from a system that has already been attacked.
Note: Tools such as EventCombMT, DumpEL, and Microsoft Operations Manager (MOM) can help you determine
how much a system has been attacked. Third-party intrusion detection systems give advance warning of attacks,
and other tools will show file changes on your systems.
Protecting Evidence
In many cases, if your environment has been deliberately attacked, you may want to take legal action against the
perpetrators. In order to preserve this option, you should gather evidence that can be used against them, even if
a decision is ultimately made not to pursue such action. It is extremely important to back up the compromised
systems as soon as possible. Back up the systems prior to performing any actions that could affect data integrity
on the original media.
Someone skilled in computer forensics should make at least two complete bit-for-bit backups of the entire
system using new, never-before-used media. At least one backup should be on a write-once, read-many media
such as a CD-R or DVD-R. This backup should be used only for prosecution of the offender and should be
physically secured until needed.
The other backup can be used for data recovery. These backups should not be accessed except for legal
purposes, so you should physically secure them. You will also need to document information about the backups,
such as who backed up the systems, at what time, how they were secured, and who had access to them.
Once the backups are performed, you should remove the original hard disks and store them in a physically
secure location. These disks can be used as forensic evidence in the event of a prosecution. New hard disks
should be used to restore the system.
In some cases, the benefit of preserving data might not equal the cost of delaying the response and recovery of
the system. The costs and benefits of preserving data should be compared to those of faster recovery for each
event.
For extremely large systems, comprehensive backups of all compromised systems might not be feasible. Instead,
you should back up all logs and selected, breached portions of the system.
If possible, back up system state data, as well. It can take months or years until prosecution takes place, so it is
important to have as much detail of the incident archived for future use.
Often the most difficult legal aspect of prosecuting a cyber crime is collecting evidence in a manner acceptable to
the particular jurisdiction's laws of evidence submission. Hence, the most critical component to the forensic
process is detailed and complete documentation of how systems were handled, by whom, and when, in order to
demonstrate reliable evidence. Sign and date every page of the documentation.
Once you have working, verified backups, you can wipe the infected systems and rebuild them. This will enable
you to begin running your operation again. The backups provide the critical, untainted evidence required for
prosecution. A different backup than the forensic backup should be used to restore data.
Recovering Systems
How you recover your system will generally depend on the extent of the security breach. You will need to
determine whether you can restore the existing system while leaving intact as much as possible, or if it is
necessary to completely rebuild the system.
Restoring data presumes, of course, that you have clean backups ? backups made before the incident occurred.
File integrity software can help pinpoint the first occurrence of damage. If the software alerts you to a changed
file, then you know that the backup you made before the alert is a good one and should be preserved for use
when rebuilding the compromised system.
An incident could potentially corrupt data for many months prior to discovery. It is, therefore, very important that
as part of your incident response process, you determine the duration of the incident. (File/system integrity
software and intrusion detection systems can assist you in this.) In some cases, the latest or even several prior
backups might not be long enough to get to a clean state, so you should regularly archive data backups in a
secure off-site location.
Costs due to the loss of competitive edge from the release of proprietary or sensitive information.
Legal costs.
Labor costs to analyze the breaches, reinstall software, and recover data.
Costs relating to system downtime (for example, lost employee productivity, lost sales, replacement of
hardware, software, and other property).
Costs relating to repairing and possibly updating damaged or ineffective physical security measures
(locks, walls, cages, and so on).
Other consequential damages such as loss of reputation or customer trust.
Hacking Exposed Windows 2000 by Joel Scambray and Stuart McClure (McGraw-Hill Professional Publishing,
ISBN: 007292623).
Handbook for Computer Security Incident Response Teams on the SEI Web site at
http://go.microsoft.com/fwlink/?LinkId=22398.
Forum of Incident Response and Security Teams (FIRST) on the FIRST Web site at
http://go.microsoft.com/fwlink/?LinkId=22399.
Incident Response: Investigating Computer Crime by Chris Prosise and Kevin Mandia (McGraw-Hill
Professional Publishing, ISBN: 00723829).
The Internet Security Guidebook: >From Planning to Deployment by Juanita Ellis and Tim Speed (Academic
Press, ISBN: 0223747).
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