It now has its own Wikipedia page called Conficker as the worm is also known as Downup, Downadup, Conficker, and Kido.
According to the Wikipedia article, the computer work first appeared in October 2008 but spread fast after the first of the year. It specifically targets Microsoft Windows and Windows Server services using Windows 2000, Windows XP, Windows Vista, Windows Server 2003 and Windows Server 2008. It has infected a few governments and hospitals, but mostly corporate computer networks.
On October 15, 2008 Microsoft released a patch to fix the bug. Heise Online estimated that it had infected 2.5 million PCs by January 15, 2009, while The Guardian estimated 3.5 million infected PCs. By January 16, 2009, an antivirus software vendor reported that Conficker had infected almost 9 million PCs making it one of the most widespread infections in recent times. Conficker is reported to be one of the largest botnets created because 30 percent of Windows computers do not have a Microsoft Windows patch released in October 2008.
The virus can spread through websites and USB drives, like flash drives, cameras, portable hard drives, and other USB connecting devices that trigger AutoRun, so Microsoft is recommending people upgrade their Windows programs and turn off AutoRun. read more