Although Witty infected only about 12,000 machines--none of them home PCs--the worm was still a pretty big deal. It exploited a hole in Internet Security Systems firewall and security software packages, and it spread rapidly just days after the vulnerability was announced. The worm 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).
Years: 2008-Present (new variants)
Predicted outcome: Not applicable
Actual outcome: Still not dead
Koobface, introduced in 2008, is a computer worm that targets social networking Websites. It can infect all three of the major operating systems--Windows, Mac OS X, and Linux (to a limited extent)--and can gain username/password information, but not financial information, from infected computers.
"Koobface" infects users via Facebook messages. Unlike some worms, Koobface requires some effort on the part of the user in order for it to infect a computer. First, it delivers a Facebook message with a link from the account of an infected user. The potential victim must then click on the link, download a file (usually disguised as an update to Adobe Flash Player), and then run the file. If they do so, Koobface can infect the computer and use it to send more messages.