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Vista raises the bar for flaw finders
Robert Lemos, SecurityFocus 2007-01-29

Microsoft launched its latest operating system--Windows Vista--on Monday, a move that will make finding easily exploitable vulnerabilities a lot harder, according to security researchers.

In a launch event in New York City, the software giant took the wraps off of both Windows Vista and its Office 2007 productivity suite. Long awaited, Windows Vista brings together a number of security features, some aimed at hardening the operating system against attack and others designed to encourage users to make security a priority when using their PCs.

"None of the features in Windows Vista, either individually or together, are meant to be bulletproof," said Stephen Toulouse, senior product manager for Microsoft's Security Technology Unit. "But the defense-in-depth will significantly raise the security level compared to Windows XP."

The launch of its latest operating system comes five years after the company restructured its approach to software security with the Trustworthy Computing Initiative. The revamped strategy--prompted by the Code Red and Nimda worms that struck a massive number of the software giant's customers in the summer of 2001--led to a massive push to educate developers and provide tools to weed out software bugs. In 2004, Microsoft refocused Windows XP Service Pack 2, making the update almost completely about security.

While other applications, including Internet Explorer 7 and Office 2007, have benefited from Microsoft's secure development lifecycle, the development of Windows Vista was the first time the software giant's consumer operating system was designed from the ground up with a focus on security. For example, the operating system enforces least-privilege rules of access, requesting the user's password to execute certain higher privilege tasks. The software giant has also improved the operating system's firewall and revamped the Security Center to give more information to users. Internet Explorer 7 bring additional security enhancements, such as limiting ActiveX controls and significant anti-phishing features.

For security researchers, however, it's what's under the hood that matters. Three major features will make Vista more difficult to exploit even when vulnerabilities are found: Kernel Patch Protection, Data Execution Prevention and Address Space Layout Randomization.

The controversial Kernel Patch Protection, also known as PatchGuard, limits the practice of some software developers of creating add-on features for the operating system by patching the kernel, the core system software. Many security software makers have criticized the feature because it limits their software's ability to modify the core features offered by the Windows operating system.

"This is especially popular among anti-virus products, which sometimes use exactly the same hooking techniques as some popular malware, like rootkits," Joanna Rutkowska, senior researcher for COSEINC Advanced Malware Labs, said in an e-mail interview with SecurityFocus. "This is not good, not only because it may have potential impact on system stability, but it also confuses malware detection tools."

Such restrictions are good for the overall security of the Windows platform, but it's not comprehensive by any means, Rutkowska said. PatchGuard only protects against modifications to code and static-kernel objects, what Rutkowska calls type-I infections. It does not detect modifications to dynamic structures (type-II infections) nor does it detect modifications to code running through hardware virtualization (type-III infections), she said.

That's not surprising, because PatchGuard is not really about stopping malicious software from subverting the kernel, but preventing any software from destabilizing the system, said Ken Johnson, a software developer at remote-access provider Positive Networks.

"As far as I can tell, (PatchGuard) is a mechanism to force third-party driver (developers) to clean up their act and stop releasing poorly written drivers that destabilize customer computers and introduce security holes," Johnson said.

In a recent article in the technical publication Uninformed, Johnson--writing under the pseudonym "Skywing"--described several deficiencies in the latest version of PatchGuard, version 2. Microsoft's programmers are currently studying the claims, said the software giant's Toulouse.

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