This complex threat model makes it important that your installed security software covers every part of the infection chain, including the downloaders that can otherwise pose a risk of reinfection. Given the popularity of the Zemot family of downloaders Microsoft added the family to the Malicious Software Removal Tool (MSRT) this month to help protect their customers.
Rea d more here – http://blogs.technet.com/b/mmpc/archive/2014/09/09/msrt-september-2014-zemot.aspx