Conficker (It's short for CONFIGURATION F@#%ER!), also known as Downup, Downadup and Kido, is a computer worm that surfaced in October 2008 and targets the Microsoft Windows operating system. The worm exploits a previously patched vulnerability in the Windows Server service used by Windows 2000, Windows XP, Windows Vista, Windows Server 2003, Windows Server 2008, Windows 7 Beta, and Windows Server 2008 R2 Beta. The worm has been unusually difficult for network operators and law enforcement to counter because of its combined use of advanced malware techniques.
Although the origin of the name "conficker" is not known with certainty, Internet specialists and others have speculated that it is a German portmanteau fusing the term "configure" with "ficken", the German word for "fuck." Microsoft analyst Joshua Phillips describes "conficker" as a rearrangement of portions of the domain name "trafficconverter.biz"
