The Sobig.F worm is officially the fastest spreading virus to date, according to antivirus firm MessageLabs, which has stopped nearly two million infected emails since the virus was first reported at the beginning of this week.

Unsuspecting email users have been hit in droves, with hundreds of thousands of home and business PCs infected over the past few days.

At its peak, one in every 17 emails intercepted by MessageLabs was infected by Sobig.F and according to reports, ISP AOL has blocked more than 11.5 million copies of the worm since its first appearance on Monday.

The worm has spread faster than the infamous Klez and Kournikova viruses. Its nearest competitor was September 2000's LoveBug where one in every 28 messages was infected.

According to MessageLabs, Sobig.F performs a mass-mailing routine every 10 minutes on infected machines and attempts to spread over open networks shares every 30 minutes. It also attempts to update itself every hour and install malicious code via various remote websites.

If you haven't already downloaded a patch then click here. As always if you are suspicious of an email you receive then delete it.

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MessageLabs