Microsoft Security Bulletin MS11-086 - Important
Vulnerability in Active Directory Could Allow Elevation of Privilege (2630837)
Published: Tuesday, November 08, 2011
This security update resolves a privately reported vulnerability in Active Directory, Active Directory Application Mode (ADAM), and Active Directory Lightweight Directory Service (AD LDS). The vulnerability could allow elevation of privilege if Active Directory is configured to use LDAP over SSL (LDAPS) and an attacker acquires a revoked certificate that is associated with a valid domain account and then uses that revoked certificate to authenticate to the Active Directory domain. By default, Active Directory is not configured to use LDAP over SSL.
This security update is rated Important for Active Directory, ADAM, and AD LDS when installed on supported editions of Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008 (except Itanium), Windows 7, and Windows Server 2008 R2 (except Itanium). For more information, see the subsection, Affected and Non-Affected Software, in this section.
The security update addresses the vulnerability by changing the way that Active Directory verifies certificates against the Certificate Revocation List (CRL). 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. The majority of customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.
For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service.
See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.