Actual outcome: An estimated 10 million home/business/government computers under its control

The (also known as Downup, Downadup, and Kido), first detected in 2008, was a . The worm used advanced malware techniques to take over machines and turn them into that the worm's authors could control remotely. The was believed to be one of the largest computer infections since 2003, and analysts have suggested that were affected.

Conficker : 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 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 for information leading to the arrest and conviction of Conficker's authors.They are still at large.