This security update resolves one privately reported vulnerability and one publicly disclosed vulnerability in Microsoft Windows. The vulnerabilities could allow elevation of privilege if an attacker logs on to an affected system and runs a specially crafted application that exploits the vulnerability. An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability. The vulnerability could not be exploited remotely or by anonymous users.

This security update is rated Important for all 32-bit editions of Windows XP and Windows Server 2003; Windows 7 for x64-based Systems; and Windows Server 2008 R2 for x64-based Systems. 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 Windows User Mode Scheduler handles a particular system request and the way that Windows manages BIOS ROM. 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.

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.

Known Issues. None

Reference: http://technet.microsoft.com/en-us/security/bulletin/ms12-042