A dodgy update to Microsoft's anti-virus software on Tuesday meant users of the software were wrongly warned that Google's homepage was infected with the infamous Blackhole Exploit Kit.
Users of Microsoft's Forefront corporate security products (here) and freebie Security Essentials scanner software (here) were both affected by the snafu. Following the false positive update, surfers who visited Google.com were falsely warned* that it had been contaminated with a "severe" threat – specifically Exploit:JS/Blacole.BW.
Taken at face value, the warning implied that users visiting the site were being hit with scripts that attempted to use browser exploits and the like to push malware onto vulnerable PCs. Microsoft's Technet support forums soon filled up with notes and queries over the alarming warning, which turned out to be entirely bogus. Microsoft published updated definition files that avoided the false positive within four hours of the first report of the glitch.
False alarms involving anti-virus software affect all vendors from time to time. Such problems, as is the case with Microsoft's misfiring Valentine's Day update, normally only cause minor inconvenience and confusion. False positives only really become a serious problem when system files are incorrectly classified as malign, leaving users with unstable – and in some cases unbootable – Windows boxes. ®
*IE users were hit by the false positive as soon as they visited Google.com. Firefox fans were only warned when they initiated a search, according to posts on Microsoft's Technet support forum. There have been no reports of alerts for Windows users using either Google Chrome or Opera.