German antivirus vendor Avira on Wednesday issued a temporary fix for a bug that blocked trusted processes and safe applications, and in some cases even prevented PCs from booting.
Avira also offered up more details about the glitch, which was found in a Monday software update issued to paid subscribers.
A problem with the "Service Pack 0" update for several of Avira's antivirus products for Windows puts the software's ProActiv behavioral monitoring component on "tilt," causing it to block a number of trusted OS processes like the Windows registry editor and task scheduler, as well as programs like Microsoft Office, OpenOffice, Google Updater, and the Opera Web browser, according to security blogs and users on the Avira support forums.
"We contacted all of our users to let them know about our fix to the ProActiv situation this morning," Travis Witteveen, Avira's chief operating officer, said in a statement emailed to PCMag. "The issue only arose on 32-bit Windows Premium, Suite, and Professional products, which had ProActiv turned on.
"By default ProActiv is an opt-in feature, so the infected base was not the entire base," Witteveen continued. "We do not know the exact number of those impacted, but we are confident we reacted immediately and communicated thoroughly."
According to H-Online, Avira's buggy update was downloaded more than 70 million times before the company pulled the plug on it. Those downloads do include installations on machines running the unaffected free version of Avira's AV product as well as systems where ProActiv is not turned on, however.
Avira's new update for users of its affected Avira Professional Security, Avira Antivirus Premium 2012, and Avira Internet Security 2012 products simply turns off the ProActiv component. While the company said that "current versions of Avira's Windows desktop products are now operating smoothly" thanks to the fix, the solution is temporary.
"We are working hard to get to the bottom of the problem. Until a permanent fix is available, the ProActiv module remains disabled," Avira said in a website post detailing the issue and describing the temporary fix.
The post also describes steps to take if the problem persists after installing the fix. Avira users who are experiencing boot shutdowns after installing the original Service Pack 0 update are advised to try starting their PCs in Safe Mode and then deactivating ProActiv by following these steps.
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