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Reg reader trapped in McAfee Catch 22

Nimda spawns heuristic headache

A Register reader ran into a Catch 22 situation when he tried to inform McAfee that its antivirus software was generating false warnings about the Nimda worm.

Alarm bells triggered when Russell Elliott tried to browse www.kingcomp.net, when McAfee's antivirus tools warned him that the site was infected with Nimda.

Kingcomp was able to tell him the site had been cleaned up but its "page not available" (404.html) file still had a reference to a text string used by the Nimda. This was still there even though the payload had been wiped off its servers.

Russell tried to advise McAfee it was catching some systems that had been actually been cleaned and wanted to quiz it on its technology.

But since his email contained the text string used to launch Nimda "window.open <"readme.eml", null" (we've changed ( to < in order to avoid getting caught ourselves), his email was quarantined and deleted.

Subsequent correspondence with support staff prompted requests from them to explain what operating system and version of VirusScan he was using, rather missing the point.

You can debate whether automatic detection (heuristics) in virus scanners does more good than harm, and we're inclined to argue that the occasional false alarm is a price worth paying. Being wrongly told a site is infected with Nimda is annoying but how does that inconvenience compare with having a virus slip through your protection(something heuristics is designed to prevent)?

That said, Russell has a reasonable question when he asks McAfee: "wouldn't it be better to define your virus definitions around the PAYLOAD (which is binary and more difficult to modify), instead of the launch mechanism." ®

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