Microsoft issued a critical security alert relevant to Windows 2000, XP and Server 2003 systems. For more information, please read below.
Executive Summary
This security update resolves a privately reported vulnerability in the Server service. The vulnerability could allow remote code execution if an affected system received a specially crafted RPC request. On Microsoft Windows 2000, Windows XP, and Windows Server 2003 systems, an attacker could exploit this vulnerability without authentication to run arbitrary code. It is possible that this vulnerability could be used in the crafting of a wormable exploit. Firewall best practices and standard default firewall configurations can help protect network resources from attacks that originate outside the enterprise perimeter.
This security update is rated Critical for all supported editions of Microsoft Windows 2000, Windows XP, Windows Server 2003, and rated Important for all supported editions of Windows Vista and Windows Server 2008. For more information, see http://www.microsoft.com/technet/security/bulletin/MS08-067.mspx.
The security update addresses the vulnerability by correcting the way that the Server service handles RPC requests.
Recommendation. Microsoft recommends that customers apply the update immediately.