alert tcp $HOME_NET any -> $EXTERNAL_NET 25 (msg:"BLEEDING-EDGE VIRUS Bagle-BB SMTP Outbound"; flow:to_server,established; content:"UEsDBBQAAAAIA"; content:"XjAAAAQ4AAA"; distance:10; within:22; reference:url,www.sophos.com/virusinfo/analyses/trojdropperbb.html; reference:url,isc.sans.org/diary.php?date=2005-09-12; classtype:trojan-activity; sid:2002367; rev:1;)