Is a computer worm infect corporate networks or institutions and open a link position to which pull information from computers on the network was launched in October 2008 and targeted at Microsoft operating system taking advantage of a weakness in one of the Windows Services ,a (windows server service ) to spread across computers and network and is the Conficker worm of the most difficult the most serious worms to deal with it because it uses many of the techniques and complex instructions to prevent anti-virus software control , this worm infected about 15 million servers from Microsoft servers which Microsoft in February 2009 to pay the announcement of the reward of 250 thousand dollars to anyone who cast information for designers this worm ! Microsoft , in collaboration with several companies to eliminate completely Conficker worm by mid -April 2009