Sophos has apologised after releasing a faulty signature update that flagged up legitimate Mac OS X system files as infected with a new low-risk worm, Inqtana-B.
The faulty signature file, issued on Tuesday, February 21, falsely identified a number of component files of Microsoft Office applications as infectious.
The UK-based anti-virus firm issued a new update in short time, two hours after the dodgy signature files went out. Inqtana-B has not been detected in the wild, so the false alert on legitimate files triggered by the Sophos update is doubly annoying for anyone affected, particularly if users had set their software to auto-detect infected files. As one Reg reader notes: "This will completely break MS Office and any users this has happened to will have to reinstall Office."
A Sophos spokesman said that its anti-virus software would not delete files by default and would normally ask for permission. He added that a "relatively low" number of Sophos clients had been affected. But this small number did include a couple of US Universities. "Only enterprises with Mac OS X computers would be affected and, of those, only those that did a scheduled scan during the short time the update was available would have been affected. Most got away with it."
Faulty anti-virus signature updates are not uncommon. Sophos blamed this week's mishap on testing particular to its security software on the Mac OS X platform, which is a relatively recent addition to its portfolio. The firm is to revamp testing procedures to prevent repetition.