In Pictures: 20 notorious worms, viruses and botnets

Sasser

In 2004, Sasser malware exploited a vulnerability in Microsoft Windows to propagate, which made it particularly virulent. What’s more, due to a bug in the worm’s code, infected systems turned off every couple of minutes, says Lovet.

More than one million systems were infected, AFP’s communications satellites were interrupted for hours, Delta Airlines was forced to cancel flights, the British coast guard had to go back to print maps, and a hospital had to redirect its emergency room because its radiology department was completely paralyzed by the virus. The damage amount was estimated to be more than $18 billion.

Microsoft placed a $250,000 bounty on the author’s head, who turned out to be an 18-year old German student.