Topic: Avast has apologised for mistake in Web detection (virus defs 110411-1)

[Samker]

Major freebie anti-virus scanner Avast has apologised for a cock-up defining the vast majority of the web as malign.

Rather than a Howard Beale-style insight into the state of the modern interwebs, the finding of any sites with scripts or frames - including Avast's own support forums - as malign was the result of a rogue virus definition update: http://www.imdb.com/character/ch0013121/quotes

The Czech Republic-based firm quickly realised its mistake, and released a revised definition file within a hour of discovering the problem on Tuesday morning.

In an advisory, Avast said sorry for the snafu: https://blog.avast.com/2011/04/11/false-positive-issue-with-virus-defs-110411-1

    "Virus definition update 110411-1 contained an error that resulted in a good number of innocent sites being flagged as infected. Generally, all sites with a script in a specific format were affected."

The problem is simple enough to resolve by simply manually updating definition files. Faulty definition updates are a well known shortcoming of security software suites.

Such screw-ups often result in the quarantine of benign files, bricking systems if the falsely flagged files happen to be system files. No local files were quarantined in the Avast case.

Anti-virus definition updates are routinely tested prior to release. In the Avast case this seems to have been done on a machine without internet access, hence the failure to detect a glaringly obvious problem.

An estimated 130 million users worldwide use Avast's software. The firm, like AVG and Avira, offers basic anti-virus scanner software free to consumers while making money selling security suites with added features and scanners to companies, mostly targeting small businesses.

(ElReg)