Microsoft Windows 7 Hit By Zero Day Vulnerability

Laurence Gaffié, a security researcher, has discovered a weakness in Windows 7 and published all the relevant details on the full disclosure mailing list archives at Insecure.org.

The bug has been recognised by Microsoft but its importance has been minimised by the software company. On his blog, Gaffié went as far as providing with a proof of concept which he used to remotely crash Windows 7 (and Windows Server 2008 R2) on a local area network.

Such an attack is also possible through any version of Internet Explorer even older ones (or broadcasting NetBIOS Name Server "trick") even if the system's firewall is activated. The vulnerability, which is found in the Server Message Block (SMB) file sharing protocol, could effectively be used to perform a denial of service (DOS) attack through an infinite loop.

Canada-based Gaffié also maintains that the bug was a "real proof" that Microsoft's Security Development Lifecycle had failed. The temporary solution, according to him would be to, "Close SMB feature and ports, until a real audit is provided." However, the flaw doesn't allow hackers to gain unauthorised remote access to information on any machine.

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Microsoft has rapidly released a security advisory and suggests that two ports at the firewall could be blocked to protect users from any external attacks. Older versions of Windows, Vista, Server 2008 R1, Server 2003, Windows 2000 and Windows XP are not affected by the bug.