Revision Note: V1.1 (March 8, 2011): Revised advisory FAQ to announce updated version of the MSRT and added Forefront Security for Exchange Server to the list of non-affected software.
Summary: Microsoft is releasing this security advisory to help ensure customers are aware that an update to the Microsoft Malware Protection Engine also addresses a security vulnerability reported to Microsoft. The update addresses a privately reported vulnerability that could allow elevation of privilege if the Microsoft Malware Protection Engine scans a system after an attacker with valid logon credentials has created a specially crafted registry key. An attacker who successfully exploited the vulnerability could gain the same user rights as the LocalSystem account. The vulnerability could not be exploited by anonymous users.
Microsoft Security Advisory (2491888): Vulnerability in Microsoft Malware Protection Engine Could Allow Elevation of Privilege – Version: 1.1