The Conficker worm (also known as Downup, Downadup, and Kido), first detected in 2008, was a virus that targeted Windows operating systems. The worm used advanced malware techniques to take over machines and turn them into zombie/host computers that the worm's authors could control remotely. The Conficker infection was believed to be one of the largest computer infections since 2003, and analysts have suggested that as many as 10 million machines were affected.
Conficker spread in three ways: It attacked vulnerability in the Microsoft Server service, it guessed administrator passwords, and it infected removable devices with an autorun file that executed as soon as someone plugged the device (such as a USB flash drive) into another machine. The virus was particularly notable for its ability to spread rapidly throughout business networks; home computers were less likely to be infected.
The last known variant of Conficker was effectively quashed in mid-April 2009, but the authors of the worm remain unknown. The threat was so serious that Microsoft and ICANN offered a $250,000 reward for information leading to the arrest and conviction of Conficker's authors.They are still at large.
Predicted outcome: Not applicable
Actual outcome: The fastest-spreading e-mail worm ever
In January 2004 a new e-mail worm began spreading around the Net, appearing as a transmission-error message with an attachment. If the victim ran the attachment, the worm would not only send itself out to everyone on any address book it could find but also would attach itself to any copies of Kazaa to spread via peer-to-peer networks.