This security update resolves two privately reported vulnerabilities in Microsoft Windows. The vulnerabilities could allow elevation of privilege if an attacker logs on to a users system and runs a specially crafted application. An attacker must have valid logon credentials and be able to log on locally to exploit the vulnerabilities.

This security update is rated Important for all supported editions of Windows XP (except x86-based), Windows Server 2003, Windows Vista (except x86-based), Windows Server 2008 (except x86-based), Windows 7 (except x86-based), and Windows Server 2008 R2. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerabilities by correcting the way that the AFD validates input before passing the input from user-mode to the Windows kernel. For more information about the vulnerabilities, 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 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.

Known Issues. None

Reference: http://technet.microsoft.com/en-us/security/bulletin/MS12-009