Predicted outcome: Not applicable

Actual outcome: First worm to carry a destructive payload; infected 12,000 machines

The Witty worm, first detected in 2004, was an for a number of reasons--namely, it was the first worm to carry a malicious "payload" that slowly destroyed the host computers it infected.

Although Witty infected only about 12,000 machines--none of them home PCs--the worm was still . It in Internet Security Systems firewall and security software packages, and it spread rapidly just days after the vulnerability was announced. The was called the "Witty" worm because the payload featured the phrase "(^.^) insert witty message here (^.^)."

The worm was particularly frightening for network administrators because it infected computers that should have been more secure (because of the ISS software).