[ISN] ITL Bulletin for February 2006

InfoSec News isn at c4i.org
Tue Feb 21 01:15:18 EST 2006

Forwarded from: Elizabeth Lennon <elizabeth.lennon at nist.gov>



Shirley Radack, Editor
Computer Security Division
Information Technology Laboratory
National Institute of Standards and Technology
Technology Administration
U.S. Department of Commerce

A systematic approach to managing and using software patches can help
organizations to improve the overall security of their information
technology (IT) systems in a cost-effective way.  Organizations that
actively manage and use software patches can reduce the chances that
the vulnerabilities in their IT systems can be exploited; in addition,
they can save time and money that might be spent in responding to
vulnerability-related incidents.

Patches are additional pieces of code that have been developed to
address specific problems or flaws in existing software.
Vulnerabilities are flaws that can be exploited, enabling unauthorized
access to IT systems or enabling users to have access to greater
privileges than authorized.

New vulnerabilities are discovered each day, and IT systems are
constantly threatened by new attacks. The National Vulnerability
Database (NVD), maintained by NIST's Information Technology
Laboratory, includes information about more than 16,000
vulnerabilities and reports about new vulnerabilities at the rate of
14 per day. The NVD integrates all publicly available U.S. Government
vulnerability resources and provides references to industry resources.
At the current rate of vulnerability reporting, even small
organizations with a single server can expect to spend considerable
time reviewing and applying critical patches. Organizations must be
aware of and use available security patches.  Since not all
vulnerabilities have related patches, however, it is essential to
apply other security controls that are selected through an analysis of
the vulnerabilities and the risks to systems.

NIST Special Publication 800-40, Version 2, Creating a Patch and
Vulnerability Management Program

NIST recently issued Special Publication (SP)  800-40, Version 2,
Creating a Patch and Vulnerability Management Program. Written by
Peter Mell of NIST, Tiffany Bergeron of The MITRE Corp., and David
Henning of Hughes Network Systems LLC, NIST SP 800-40 was developed
with the support of the United States Computer Emergency Readiness
Team (US-CERT), an organization in the Department of Homeland Security
that coordinates defense against and responses to cyber attacks.
Version 2 supplements the earlier version of NIST SP 800-40, entitled
Procedures for Handling Security Patches (August 2002). Both
publications are available at:  

NIST SP 800-40 provides guidance for organizational security managers
who are responsible for designing and implementing security patch and
vulnerability management programs and for testing the effectiveness of
the programs in reducing vulnerabilities.  The guidance is also useful
to system administrators and operations personnel who are responsible
for applying and testing patches and for deploying solutions to
vulnerability problems.

Topics covered in Version 2 include the principles and methodologies
for patch and vulnerability management, security metrics for testing
the effectiveness of the patch and vulnerability process, management
issues such as setting priorities for patch efforts, and federal
government resources available to support the patch and vulnerability
processes. The appendices include a list of acronyms, a glossary of
terms, and information on patch and vulnerability issues available
from industry sources.

Security Patches

Timely patching of software is generally recognized as critical to
maintaining the operational availability, confidentiality, and
integrity of IT systems. Failure to keep operating system and
application software patched is one of the most common problems that
security and IT professionals must handle. New patches are released
daily, and even experienced system administrators may have difficulty
in keeping informed about the new patches and in deploying them
properly in a timely manner.

Most major attacks on IT systems over the past few years have targeted
known vulnerabilities for which patches had existed before the
outbreaks.  Information about patches can also lead to problems for
organizations. Often when a patch is released, attackers will make
concerted efforts to reverse engineer the patch swiftly (in days or
even hours), to identify the vulnerability, and to develop and release
code that exploits the vulnerability. As a result, the period
immediately following the release of a patch can be particularly
dangerous for organizations because of the time that they need to
obtain, test, and deploy the patch.

NIST Recommendations for Patch and Vulnerability Management

Organizations should implement a systematic, accountable, and
documented process for managing exposure to vulnerabilities through
the timely deployment of patches. NIST recommends that federal
agencies implement the following actions to assist in patch and
vulnerability management:

Create a patch and vulnerability group (PVG) to facilitate the
identification and distribution of patches within the organization.

The PVG should be specially tasked to implement the patch and
vulnerability management program throughout the organization. The PVG
is the central point for vulnerability remediation efforts, such as
implementing patching and configuration changes for operating system
and application software. Since the PVG should work actively with
local administrators, large organizations may need to organize several
PVGs;  these groups could work together or they could be structured
hierarchically with an authoritative top-level PVG.

The duties of a PVG include the following:

1. Inventory the organization's IT resources to identify the hardware
equipment, operating systems, and software applications that are used
within the organization.

2. Monitor security sources for vulnerability announcements, patch and
non-patch methods of remediation, and emerging threats that match up
with the software within the system inventory of the PVG.

3. Prioritize the order in which the organization addresses the
remediation of vulnerabilities, based on analysis of risks to systems.

4. Create a database of remediation methods that need to be applied
within the organization.

5. Conduct the testing of patches and non-patch remediation methods on
IT devices that use standardized configurations.

6. Oversee the vulnerability remediation process in the organization.

7. Distribute vulnerability and remediation information to local

8. Perform automated deployment of patches to IT devices using
enterprise patch management tools.

9. Configure automatic updates of applications whenever possible and

10. Verify vulnerability remediation through network and host
vulnerability scanning.

11. Train administrators on how to apply vulnerability remediation.

Use automated patch management tools to expedite the distribution of
patches to systems.

Widespread manual patching of computers is becoming ineffective as the
number of patches that need to be installed grows and as attackers
continue their rapid development of code that exploits
vulnerabilities. While patching and vulnerability monitoring may
appear to be overwhelming tasks, the use of automated patching
technology can make the job less burdensome.  Enterprise patch
management tools allow the PVG, or a group they work closely with, to
automatically distribute updates and patches to many computers
quickly. All medium- to large-size organizations should use enterprise
patch management tools for most of their computers.  Even small
organizations should consider migrating to the use of automated
patching tools.

Deploy enterprise patch management tools using a phased approach.

Implementing patch management tools in phases allows process and user
communication issues to be addressed with a small group before the
patch application is deployed throughout the organization. Most
organizations should deploy patch management tools first for their
standardized desktop systems and single-platform server farms of
similarly configured servers.  Once this has been accomplished,
organizations should address the more difficult issue of integrating
multiplatform environments, nonstandard desktop systems, legacy
computers, and computers with unusual configurations. Manual methods
may be needed for operating systems and applications not supported by
automated patching tools, as well as for some computers with unusual
configurations, such as embedded systems, industrial control systems,
medical devices, and experimental systems. For these systems, there
should be a written and implemented procedure for the manual patching
process, and the PVG should coordinate the local administrator

Assess and mitigate the risks associated with deploying enterprise
patch management tools.

Enterprise patch management tools, while usually effective at reducing
risk, can also create additional security risks for an organization.  
For example, an attacker could break into the organization’s central
patch management computer and use the enterprise patch management tool
as a way to distribute malicious code efficiently.  Organizations
should partially mitigate these risks through the application of
standard security techniques that should be used when deploying any
enterprise-wide application.

Consider using standardized configurations for IT resources.

Organizations will find it much easier and less costly to implement a
patch and vulnerability management program when they use standard
configurations. Further, the PVG may not be able to test patches
adequately if IT devices use nonstandard configurations. Enterprise
patch management tools may be ineffective if deployed within an
environment where every IT device is configured uniquely, because the
side effects of the various patches on the different configurations
will be unknown. Comprehensive patch and vulnerability management is
almost impossible within large organizations that do not deploy
standard configurations. Organizations should focus their
standardization efforts on the systems that make up a significant
portion of their IT resources.

Measure the effectiveness of the patch and vulnerability management
program in a consistent manner and apply corrective actions as

An organization can measure its susceptibility to attack, based on the
number of patches needed, the number of vulnerabilities identified,
and the number of network services running on a per-system basis.
These measurements should be taken individually for each computer
within the system, and the results then aggregated to determine the
system-wide result. A second measure to be made is the mitigation
response time, which is based on how quickly an organization can
identify, classify, and respond to a new vulnerability and mitigate
the potential impact of the vulnerability within the organization. The
third measure to be made is the cost of the patch and vulnerability
program. This may be difficult to measure because actions are often
split between many different personnel and groups. The four main costs
that should be taken into consideration are: the PVG, system
administrator support, enterprise patch and vulnerability management
tools, and incidents that occurred due to failures in the patch and
vulnerability management program.

The patch and vulnerability metrics that are taken for a system or IT
security program should reflect the patch and vulnerability management
maturity level. For example, attack susceptibility metrics such as the
number of patches, vulnerabilities, and network services per system
are generally more useful for a program with a low maturity level than
a high maturity level. Organizations should document what metrics will
be taken for each system and the details of each of those metrics.
Realistic performance targets for each metric should be communicated
to system owners and system security officers. Once these targets have
been achieved, more ambitious targets can be set. The level of patch
and vulnerability security should be set carefully to avoid
overwhelming system security officers and system administrators.

NIST Publications That Support Patch and Vulnerability Management

NIST publications can help you in planning and implementing a
comprehensive approach to IT security. For information about the NIST
publications that are referenced in the patch and vulnerability
management guide, as well as other security-related publications, see

NIST Special Publication (SP) 800-18, Revision 1, Guide for Developing
Security Plans for Federal Information Systems, helps federal agencies
develop plans for their IT systems, by documenting their security
requirements and describing the controls that are in place or that are
planned for meeting those requirements.

NIST SP 800-23, Guideline to Federal Organizations on Security
Assurance and Acquisition/Use of Tested/Evaluated Products, helps
organizations acquire and use security-related information technology

NIST SP 800-26, Security Self-Assessment Guide for Information
Technology Systems, provides a method for organizations to determine
the status of their information security systems and to establish a
target for improvement, if needed.  The guide defines maturity levels
for various aspects of an IT security program.

NIST SP 800-51, Use of the Common Vulnerabilities and Exposures (CVE)
Vulnerability Naming Scheme, describes methods for identifying and
organizing known IT system vulnerabilities and provides guidance in
the acquisition of CVE-compatible products and services. The CVE is a
resource for the IT security community, providing a comprehensive list
of publicly known vulnerabilities, an analysis of the authenticity of
newly published vulnerabilities, and a unique name for each

NIST SP 800-55, Security Metrics Guide for Information Technology
Systems, describes the security metrics development and implementation
process. Implementation of this process will help demonstrate the
adequacy of in-place security controls, policies, and procedures. It
also will help justify security control investments and can be used in
identifying necessary corrective actions for deficient security

NIST SP 800-61, Computer Security Incident Handling Guide, discusses
how to organize a security incident response capability and how to
handle incidents including denial of service, malicious code,
unauthorized access, and inappropriate use of systems.

NIST SP 800-70, Security Configuration Checklists Program for IT
Products­Guidance for Checklists Users and Developers, provides
guidance on creating and using security configuration checklists,
which are helpful tools for standardization. NIST SP 800-70 describes
the Security Configuration Checklists Program for IT Products, which
collects reviewed checklists for a variety of operating systems and
applications.  Information about the checklists repository is
available at http://csrc.nist.gov/checklists/index.html.

Federal Information Processing Standard (FIPS)  199, Standards for
Security Categorization of Federal Information and Information Systems
(February 2004), establishes security categories for federal
information and information systems.  The categories are determined
based on the potential impact of a loss of confidentiality, integrity,
or availability of information or an information system. The security
categories should be used to prioritize multi-system vulnerability
remediation efforts.

The National Vulnerability Database (NVD)  integrates all of the
US-CERT vulnerability mitigation products, including vulnerability
notes and National Cyber Alert System products.  It contains a
fine-grained search engine that allows users to search for
vulnerabilities containing a variety of characteristics. For example,
users can search on product characteristics such as vendor name,
product name, and version number, or on vulnerability characteristics
such as severity, related exploited range, and type of vulnerability.
The NVD provides a vulnerability summary for each CVE vulnerability.
Each summary contains attributes of the vulnerability (including a
short summary and vulnerable version numbers) and links to advisories,
patches, and other resources related to the vulnerability. The NVD is
available at http://nvd.nist.gov/.

Any mention of commercial products or reference to commercial
organizations is for information only; it does not imply
recommendation or endorsement by NIST nor does it imply that the
products mentioned are necessarily the best available for the purpose.

Elizabeth B. Lennon
Information Technology Laboratory
National Institute of Standards and Technology
100 Bureau Drive, Stop 8900
Gaithersburg, MD 20899-8900
Telephone (301) 975-2832
Fax (301) 975-2378

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