Patch Tuesday: Gaping security hole in Windows Media Player

The disclosure forms part of this month's Patch Tuesday release where Microsoft shipped three bulletins with patches for security holes in Windows and Microsoft Office.

The most serious of the three bulletins is MS11-015 and Microsoft is urging all Windows users to apply this update immediately because of the severity and the likelihood of working attack code within 30 days.

This security update resolves one publicly disclosed vulnerability in DirectShow and one privately reported vulnerability in Windows Media Player and Windows Media Center. The more severe of these vulnerabilities could allow remote code execution if a user opens a specially crafted Microsoft Digital Video Recording (.dvr-ms) file. In all cases, a user cannot be forced to open the file; for an attack to be successful, a user must be convinced to do so.

The Windows Media update is rated "critical" for affected editions of Windows XP (including Windows XP Media Center Edition 2005); all supported editions of Windows Vista and Windows 7; and Windows Media Center TV Pack for Windows Vista.

The biggest problem exists in the way that Windows Media Player and Windows Media Center handle .dvr-ms files.

This vulnerability could allow an attacker to execute arbitrary code if the attacker convinces a user to open a specially crafted .dvr-ms file. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

For businesses using the Microsoft Groove workspace sharing product, pay special attention to MS11-016, which covers a remote code execution issue in Groove.

This security update resolves a publicly disclosed vulnerability in Microsoft Groove that could allow remote code execution if a user opens a legitimate Groove-related file that is located in the same network directory as a specially crafted library file.

The vulnerability exists in the way that Microsoft Groove 2007 handles the loading of DLL files. "An attacker who successfully exploited this vulnerability could take complete control of an affected system," Microsoft warned.

This month's Patch Tuesday batch also includes MS11-017, an "important" bulletin covering a code execution flaw in the Windows Remote Desktop Client.

The vulnerability could allow remote code execution if a user opens a legitimate Remote Desktop configuration (.rdp) file located in the same network folder as a specially crafted library file.

It's important to note that there are several outstanding issues that were not patched this month.