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A little-known Russian security firm claimed Monday that it's spotted vulnerabilities in Microsoft Windows XP SP2, and has taken the unusual step of producing its own patch for the bug.
Researchers at Moscow-based Positive Technologies said that they uncovered the flaws in Windows XP SP2's DEP (Data Execution Mechanism) back in early October, and reported it to Microsoft more than a month ago.
When it didn't receive a response, Positive released details of the vulnerability on its Web site, and posted a patch that supposedly temporarily fixes the problem.
As implemented in SP2, DEP is a collection of hardware and software technologies that do additional checks on memory to protect against malicious code exploits like buffer overflows. While hardware DEP technologies -- such as those in some AMD processors and in upcoming CPUs from Intel -- can protect code throughout the system from such exploits, the software-only DEP that Positive claims is buggy only protects a specific number of Windows' system files.
The utility which can be downloaded from the Positive Web site sets a global flag on the system to block at least one possible exploit vector.
But analysts warn users to be wary of applying non-vendor patches.
"It's just too dangerous," said John Pescatore, a vice president at Gartner, and one of the research firm's security experts. "We tell clients 'never accept patches from anyone but the vendor.' There's no way a major firm -- like an Oracle or a SAP -- could do full regression testing on a patch for another vendor's product, much less a little company like [Positive]."
Recently, Microsoft has been vocal in its denunciations of security firms and researchers who publicize details of vulnerabilities before the Redmond, Wash.-based developer has a chance to create and release a patch.
Although Pescatore dismissed self-patching, he sympathized with the Positive Technologies of the world when it comes to releasing information.
"I don't believe disclosure should wait forever. We tried that a couple of years ago, and what happened was that vendors never released patches," he said. "You don't want a vulnerability disclosed the exact instant it's discovered, or even days later, but a month is right on that borderline of reasonableness.
"Even if [a vendor] doesn't have a patch, they usually have a workaround by then."