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Microsoft Investigating Color Management Bug In Windows 7

Vulnerability could provide an attacker with kernel-level access, but Microsoft's Patch Tuesday won't have a fix.
New reports have surfaced of a previously undisclosed buffer overflow vulnerability that affects Microsoft Windows 7, among other Windows operating systems. The vulnerability was discovered by a security researcher dubbed Arkon, who made the bug public in his blog on Friday.

The timing is awkward for Microsoft, which has already released one out-of-band patch this month against the Windows Shell vulnerability, and which is preparing to release a record-setting slew of Patch Tuesday security updates.

Security research service Vupen Security warns that the vulnerability "could be exploited by local attackers to cause a denial of service or potentially gain elevated privileges." The firm says it has confirmed the vulnerability exists on fully patched versions of Microsoft Windows 7, Windows Server 2008 SP2, Windows Server 2003 SP2, Windows Vista SP2, and Microsoft Windows XP SP3.

According to security research service Secunia, the vulnerability stems from "a boundary error in win32k.sys," called when copying color values into a buffer with a fixed size that's been created via the device-independent bitmaps palette. Using a clipboard API, an attacker could specify more than 256 colors, triggering a buffer overflow, and allowing "malicious people to gain escalated privileges," said Secunia.

"Successful exploitation may allow execution of arbitrary code with kernel privileges," said the firm.

Thankfully, according to a blog post written by Arkon, the bug should be difficult to exploit. "It's really funny for me to read that people say it's exploitable," he wrote. "It's very hard to exploit it for code execution, on the edge of impossible. That's why I felt safe about releasing it publicly."

As a workaround for temporarily patching the vulnerability -- just in case -- Arkon says that a fix would involve changing user permissions for accessing the clipboard as well as display resolutions.

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