It's the fastest-spreading computer virus ever circulated by email. That's how an anti-virus company is describing the virus that exploded across the Internet this week.
MessageLabs says in the first 24 hours, it scanned more than one million copies of the "F" variant of the Sobig virus. It's been blamed for computer disruptions at businesses, colleges and other institutions around the world.
The previous record was held by Klez, which spawned about 250,000 copies during its first 24 hours earlier this year.
There have been faster outbreaks on the Internet, but they didn't spread through email. Instead, they circulated through networking functions that were built into Windows operating systems.
The Sobig virus started appearing on Tuesday, just a week after a separate virus plagued computer systems around the world. That one was called Blaster.