"W32.Blaster.B.Worm is a variant of W32.Blaster.Worm that exploits the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026), using TCP port 135. The worm targets only Windows 2000 and Windows XP machines. While Windows NT and Windows 2003 Server machines are vulnerable to the aforementioned exploit if it is not properly patched, the worm is not coded to replicate to those systems.
This worm attempts to download the penis32.exe file to the %WinDir%\System32 folder, and then execute it. This worm does not have any mass-mailing functionality."