Symantec false alert floors Macs

Anti-virus cure causes more harm than disease

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A false positive in Norton AntiVirus (NAV) for Macintosh left many Apple fans fearful that their machines had become infected with a Trojan last week. The glitch - triggered by a rogue virus definition update - left Mac users running various versions of NAV for Mac under the false impression that their swap files were infected with malware called "Hacktool.Underhand". The bogus warnings were frequently accompanied by system crashes on machines running Mac OS X.

Symantec quickly released updated definition files to resolve the problem but not before the SNAFU severally inconvenienced a significant number of Mac fans, who have vented their frustration on online discussion forums or by mailing El Reg. "I personally had to rebuild my machine as a result of instruction from Symantec staff," Mac user James Hackett from South Australia writes. "I'm not happy about losing three days work and having to do a full rebuild but am somewhat amused by the irony. As a long-term Mac user and previous net admin, who can't remember seeing a malicious Apple virus/Trojan ever it seems only right that I should be exposed to this trauma as a result of poorly written [anti-]Virus software."1

In a statement, Symantec confirmed that there was a false alarm problem with recent anti-virus updates to its Apple Mac security software, adding that the problem has now been fixed. The issue was restricted to users running Norton AntiVirus 9.x for Macintosh with virus definitions dated 28 April or Norton AntiVirus 7.0.2 or 8.x for Macintosh with virus definitions dated 1 June, it added. Norton AntiVirus for Macintosh 7.x on Mac OS 9 was not affected by the problem.

Symantec wasn't able to say how many times the dodgy definitions had been downloaded so the scope of the problem remains unclear. Users should download updated virus definition files to resolve the problem, Symantec advises. Customers should also delete all quarantined files.

Over-sensitivity in the automatic detection of viruses (or heuristics) leading to false alarms about virus infection is something of an Achilles Hell for anti-virus scanners, which by their nature need frequent updating. Last month a duff anti-virus signature update from Trend Micro floored the Windows PCs of many who applied it. The Japanese firm pulled the update 90 minutes after it was issued but the error caused mayhem to affected systems, particularly in Japan which because of the timing of the release was particularly badly hit. BitDefender, Sophos and McAfee have all been hit by similar (those less severe) glitches in the past. ®

1 Only a handful of computer viruses have ever infected Mac machines, compared to thousands that bedevil Windows users. But the comforting notion that Mac fans are immune from malware malfeasance has been called into question by the development of a proof-of-concept attack against Safari on OS X Tiger. Zaptastic - described as a "slightly evil" dashboard widget - is automatically downloaded onto machines running vulnerable Mac software that visit the site "stephan.com/widgets/zaptastic". The widget doesn't do any harm but it needs to be manually deleted and illustrates that Mac fans are becoming more exposed to security problems.

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