Back on Oct. 23, 2008, Microsoft released a critical security update for Windows: MS08-067. Isolated attacks existed at the time of the bulletin release and strongly recommended installing the security update as quickly as possible. Later, a few trojans that exploit this vulnerability were found and a month from the release of the bulletin we blogged again, this time about the first worm which exploited that vulnerability: Win32/Conficker.
KB article 891716 provides information on how to use the MSRT in enterprise environments and you can learn more about Win32/Conficker.B and about preventive measures here. The MSRT released os also addressing Win32/Banload which is a family of trojan downloaders. We will post another blog discussing Win32/Banload later this month.