Conficker

Conficker Also known as Downupor Downadup, Conficker is a worm of unknown authorshipfor Windows that made its first appearance in 2008. The name comes form the English word, configure and a German pejorative.It infects computers using flawsin the OSto create a botnet. The malware was able toinfectmore than 9 millions computers all around the world, affecting governments, businesses andindividuals. It wasone of the largest known worm infections to ever surfacecausing anestimatedamage of $9 billion.via WikipediaThe wormworks by exploiting a network service vulnerabilitythat was present and unpatched in Windows. Once infected, the worm will then reset account lockout policies, block accessto Windows update and antivirus sites, turn off certain services and lock out user accounts among many. Then, itproceeds to install software that will turn the computer into a botnet slaveand scareware to scam money off the user. Microsoftlater provided a fix and patchwith many antivirus vendors providing updates to their definitions.