Post-Patch Tuesday reports of XP SP2 and SP3 users being unable to restart their systems after applying the new MS10-015 patch led Microsoft to suspend its automatic distribution of that patch while it investigated whether the patch itself was causing the problem. The director of Microsoft's Security Response Center, Mike Reavey, said in a blog post today that the issue occurs when a system is infected with the so-called Alureon rootkit.
"The restarts are the result of modifications the Alureon rootkit makes to Windows Kernel binaries, which places these systems in an unstable state. In every investigated incident, we have not found quality issues with security update MS10-015," Reavey said. "Our guidance remains the same: customers should continue to deploy this month's security updates and make sure their systems are up-to-date with the latest anti-virus software."
The finding syncs with what some security researchers concluded earlier in the week, after initial concerns that the patch itself was flawed.
Meanwhile, distribution of the MS10-015 patch is still on hold for some systems via Automatic Update until Microsoft comes up with a fix for the issue, which it says only affects 32-bit machines. Automatic Updates for 64-bit systems are now again pushing the MS10-015 patch, which fixes a bug in the Windows kernel.
"A malware compromise of this type is serious, and if customers cannot confirm removal of the Alureon rootkit using their chosen anti-virus/anti-malware software, the most secure recommendation is for the owner of the system to back up important files and completely restore the system from a cleanly formatted disk," Reavey said.
Microsoft is working on a "simpler solution" to detect and eradicate the rootkit from infected systems, which it plans to release in a few weeks, according to Reavey.
Setting a machine to "standard" rather than "administrator" account mode typically prevents kernel malware from infecting systems, he said, and keeps antivirus signatures up-to-date is also helpful.
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