We are being hit pretty hard by Trojan Clampi. 

I have read that this Trojan tries to spread itself by using the PsExec process.  There was an article on Symantec's web site that even suggesting to block that process.  However, the MD5 hash they listed doesn't seem to work.  Keeps telling me the finger print isn't valid after trying to save it.  I have setup other Application Blocking rules and they all seem to work.  The MD5 has and the link to the support document is listed below.

http://www.symantec.com/security_response/writeup.jsp?docid=2008-011616-5036-99

0x9178451979c2192c71eb286de3e1b2f7