Microsoft Windows vulnerability - rated EXTREMELY CRITICAL

Microsoft is investigating new public reports of a vulnerability in Windows. Microsoft is also aware of the public release of detailed exploit code that could be used to exploit this vulnerability. Based on our investigation, this exploit code could allow an attacker to execute arbitrary code on the user's system by hosting a specially crafted Windows Metafile (WMF) image on a malicious Web site. Microsoft is aware that this vulnerability is being actively exploited.

A vulnerability has been discovered in Microsoft Windows, which can be exploited by malicious people to compromise a vulnerable system.

The vulnerability is caused due to an error in the handling of Windows Metafile files (".wmf") containing specially crafted SETABORTPROC "Escape" records. Such records allow arbitrary user-defined function to be executed when the rendering of a WMF file fails. This can be exploited to execute arbitrary code by tricking a user into opening a malicious ".wmf" file in "Windows Picture and Fax Viewer" or previewing a malicious ".wmf" file in explorer (i.e. opening a folder containing a malicious image file).

The vulnerability can also be exploited automatically when a user visits a malicious web site using Microsoft Internet Explorer.

NOTE: Exploit code is publicly available. This is being exploited in the wild. The vulnerability can also be triggered from explorer if the malicious file has been saved to a folder and renamed to other image file extensions like ".jpg", ".gif, ".tif", and ".png" etc.

The vulnerability has been confirmed on a fully patched system running Microsoft Windows XP SP2. Microsoft Windows XP SP1 and Microsoft Windows Server 2003 SP0 / SP1 are reportedly also affected. Other platforms may also be affected.

Microsoft Windows Metafile (WMF) format images are graphical files that can contain both vector and bitmap-based picture information. Microsoft Windows contains routines for displaying Windows Metafiles. However, a lack of input validation in one of these routines may allow a buffer overflow to occur, and in turn may allow remote arbitrary code execution.

Originally Posted by Bennett

The actual exploit has been around for awhile I believe.