Windows Security Bug Revealed After Microsoft Patch Tuesday

A security researcher discovers a bug that could be used to trigger a crash in Windows 7 and Windows Server 2008 Release 2.

Less than 24 hours after Microsoft's Patch Tuesday, a security researcher revealed a zero-day bug affecting Windows 7 and Windows Server 2008 Release 2.

Researcher Laurent Gaffie posted proof-of-concept code as well as information about the flaw on his blog and the Full Disclosure mailing list Nov. 11. The exploit takes advantage of the implementation of SMB (Server Message Block). An attacker can use the bug to remotely crash Windows 7 and Windows Server 2008 R2 on a LAN or via Internet Explorer. Technical details can be found here.

A Microsoft spokesperson said the company is looking into the matter.

"Microsoft is investigating new public claims of a possible denial-of-service vulnerability in Windows Server Message Block," the spokesperson said in an e-mail. "We're currently unaware of any attacks trying to use the claimed vulnerability or of customer impact. Once we're done investigating, we will take appropriate action to help protect customers. This may include providing a security update through the monthly release process, an out-of-cycle update or additional guidance to help customers protect themselves."

While users await a patch, Gaffie advised users close the SMB feature and ports.

November's Patch Tuesday update addressed 15 security vulnerabilities affecting Windows and Microsoft Office.