Microsoft Security Bulletin MS08-003 – Important Vulnerability in Active Directory Could Allow Denial of Service (946538)

Microsoft Security Bulletin MS08-003 – Important
Vulnerability in Active Directory Could Allow Denial of Service (946538)
Published: February 12, 2008

Version: 1.0
General Information
Executive Summary

This important security update resolves a privately reported vulnerability in implementations of Active Directory on Microsoft Windows 2000 Server and Windows Server 2003 and Active Directory Application Mode (ADAM) when installed on Windows XP and Windows Server 2003. The vulnerability could allow a denial of service condition. On Windows Server 2003 and Windows XP an attacker must have valid logon credentials to exploit this vulnerability. An attacker who successfully exploited this vulnerability could cause the system to stop responding or automatically restart.

This is an important security update for all supported editions of Microsoft Windows 2000, and a moderate security update for Windows XP, and Windows Server 2003. For more information, see the subsection, Affected and Non-Affected Software, in this section.

This security update addresses the vulnerability by validating client LDAP requests. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update at the earliest opportunity.

Known Issues. None
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Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

Affected Software
Software Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by This Update

Microsoft Windows 2000 Server Service Pack 4

Active Directory
(KB943484)

Denial of Service

Important

MS07-039

Windows XP Professional Service Pack 2

ADAM
(KB931374)

Denial of Service

Moderate

None

Windows XP Professional x64 Edition and Windows XP Professional Edition Service Pack 2

ADAM
(KB931374)

Denial of Service

Moderate

None

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Active Directory
(KB943484)

Denial of Service

Moderate

MS07-039

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

ADAM
(KB931374)

Denial of Service

Moderate

None

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Active Directory
(KB943484)

Denial of Service

Moderate

MS07-039

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

ADAM
(KB931374)

Denial of Service

Moderate

None

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Active Directory
(KB943484)

Denial of Service

Moderate

MS07-039

Non-Affected Software
Operating System

Windows Vista

Windows Vista Service Pack 1 (all editions)

Windows Vista x64 Edition

Windows Server 2008 (all editions)

Windows XP Home Service Pack 2

Windows XP Tablet Edition Service Pack 2

Windows XP Media Center Edition Service Pack 2

Windows 2000 Professional Service Pack 4

Note: These editions of Windows are not affected because they do not include ADAM or the Active Directory server component.
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Frequently Asked Questions (FAQ) Related to This Security Update

I am using an older version of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which versions or editions are affected. Other versions or editions are past their support life cycle. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older versions or editions of the software to migrate to supported versions or editions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit Microsoft Support Lifecycle. For more information about the extended security update support period for these software versions or editions, visit Microsoft Product Support Services.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit Microsoft Worldwide Information, select the country, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Windows Operating System Product Support Lifecycle FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software Active Directory Vulnerability - CVE-2008-0088 Aggregate Severity Rating

Active Directory on Microsoft Windows 2000 Server Service Pack 4

Important
Denial of Service

Important

ADAM when installed on Windows XP Professional Service Pack 2

Moderate
Denial of Service

Moderate

ADAM Windows XP Professional x64 Edition and Windows XP Professional Edition Service Pack 2

Moderate
Denial of Service

Moderate

Active Directory on Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Moderate
Denial of Service

Moderate

ADAM when installed on Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Moderate
Denial of Service

Moderate

Active Directory on Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Moderate
Denial of Service

Moderate

ADAM when installed on Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Moderate
Denial of Service

Moderate

Active Directory on Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 200 with SP2 for Itanium-based Systems

Moderate
Denial of Service

Moderate
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Active Directory Vulnerability - CVE-2008-0088

A denial of service vulnerability exists in implementations of Active Directory on Microsoft Windows 2000 and Windows Server 2003. The vulnerability also exists in implementations of Active Directory Application Mode (ADAM) when installed on Windows XP and Windows Server 2003. The vulnerability is due to improper validation of specially crafted LDAP requests. An attacker who successfully exploited this vulnerability could cause the computer to stop responding and automatically restart.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0088.

Mitigating Factors for Active Directory Vulnerability - CVE-2008-0088

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

Microsoft has not identified any mitigating factors for this vulnerability.
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Workarounds for Active Directory Vulnerability - CVE-2008-0088

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
•

Block TCP ports 389 and 3268 at the perimeter firewall

These ports are used to initiate a connection with the affected component. Blocking it at the enterprise firewall, both inbound and outbound, will help prevent systems that are behind that firewall from attempts to exploit this vulnerability. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see the TCP and UDP Port Assignments Web site.
•

To help protect from network-based attempts to exploit this vulnerability, block the affected ports by using IPSec on the affected systems.

Use Internet Protocol security (IPSec) to help protect network communications. Detailed information about IPSec and about how to apply filters is available in Microsoft Knowledge Base Article 313190 and Microsoft Knowledge Base Article 813878.
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FAQ for Active Directory Vulnerability - CVE-2008-0088

What is the scope of the vulnerability?
This is a denial of service vulnerability. An attacker who exploited this vulnerability could cause the affected system to stop responding and automatically restart. Note that the denial of service vulnerability would not allow an attacker to execute code or to elevate their user rights, but it could cause the affected system to stop accepting requests.

What causes the vulnerability?
The LDAP service performs insufficient checks for specially crafted LDAP requests.

What is Active Directory?
The main purpose of Active Directory is to provide central authentication and authorization services for Windows-based computers.

What is Active Directory Application Mode (ADAM)?
ADAM is a Lightweight Directory Access Protocol (LDAP) directory service that runs as a user service, rather than as a system service.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause a user’s system to become non-responsive and restart.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by sending a specially crafted LDAP packet to the ADAM or an Active Directory server. For Windows 2000 Server, any anonymous user with access to the target network could deliver a specially crafted network packet to the affected system in order to exploit this vulnerability. On Windows Server 2003 or systems with ADAM installed, the attacker must have valid authentication credentials in order to exploit this vulnerability.

What systems are primarily at risk from the vulnerability?
Lightweight Directory Access Protocol (LDAP) is a requirement for Active Directory and ADAM. Therefore, any system running as an ADAM or Active Directory Server is affected by this vulnerability.

What does the update do?
The update removes the vulnerability by validating the specially crafted client LDAP requests.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

Other Information
Acknowledgments

Microsoft thanks the following for working with us to help protect customers:
•

Thomas Garnier of SkyRecon for reporting the Active Directory Vulnerability – (CVE-2008-0088).
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Support
•

Customers in the U.S. and Canada can receive technical support from Microsoft Product Support Services at 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates.
•

International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
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Revisions
•

V1.0 (February 12, 2008): Bulletin published.