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White hats release exploit for critical Windows vuln

Microsoft not immune to Immunity

White-hat hackers have released reliable code that remotely exploits a critical vulnerability in the Vista and Server 2008 versions of Microsoft's Windows operating system.

The exploit code, released Wednesday by security firm Immunity, came as separate researchers with the Metasploit penetration testing project said they were close to releasing their own software targeting the network file-sharing technology known as SMB2, or Server Message Block version 2. It was first added to Vista and has since been put into other Microsoft operating systems.

The progress of ethical researchers in exploiting the bug is important because it's an indication of how other, less scrupulous hackers are likely faring. It shows that the bug, which affects newer operating systems built under a program designed to prevent such security flaws, is far from being a mere theoretical risk to the millions of people who use the products. Rather, it means attackers can use the internet to take over vulnerable machines located half-way around the globe.

"This is the kind of vulnerability that hits everybody who is sharing files with other users," Dave Aitel, CTO of Immunity, told El Reg. "It affects the most secure operating system Microsoft has put out other than Windows 7."

Aitel said it took a team of four researchers to develop an exploit for the vulnerability, which surfaced last week. Immunity researcher Kostya Kortchinsky led the effort. The exploit code works on all versions of Vista and the Service Pack 2 version of 2008, he said.

The vulnerability, which is the result of the SMB2's failure to adequately parse network negotiation requests, affects all versions of Vista, versions of Server 2008 other than R2 and the release candidate (but not the release to manufacture) version of Windows 7. Microsoft has said it plans to release updates patching the vulnerability as soon as they're ready.

Members of the Metasploit project, which produces an open-source program that tests networks for a comprehensive list of vulnerabilities, indicated they are close to releasing exploits of their own. Team member Stephen Fewer has identified the exploit identification pointer needed to remotely exploit the vulnerability in Service Pack 1 version of Windows. Once an exploit is released, they expect it to work on other vulnerable platforms as well.

Beginning with Vista, Microsoft introduced a variety of counter measures designed to make it harder for hackers to exploit bugs that inevitably escape notice during development. Address space layout randomization, data execution prevention are just two of them. While they clearly making exploitation harder, Wednesday's release by Immunity shows they are by no means foolproof.

"Lots of people, good and bad, have been trying to exploit this bug, I'd guess," Charlie Miller, a security researcher not involved in either project said. "Koysta is the first to actually succeed, which goes to show he's an awesome exploit writer." ®

Updated to add comment from Charlie Miller and to add that the exploit also works against Windows 2008 SP2.

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