Overnight we’ve seen a rash of new variants of Downloader-BAI being seeded.  Within a few hours time, over 20 new variants have been released.

This trojan can choose from the following list of subjects:

• U.S. Secretary of State Condoleezza Rice has kicked German Chancellor Angela Merkel
• Naked teens attack home director
• A killer at 11, he’s free at 21 and kill again!
• British Muslims Genocide
• 230 dead as storm batters Europe

and the following attachment names:

• Read More.exe
• Full Clip.exe
• Full Story.exe
• Video.exe

The large number of variants underscores a topic that’s been discussed much lately - The biggest trend in malware is a sort of buck-shot approach.  Create a very large number of different variants in a short span of time, hoping to gain at least a few extra hours in which to be undetected by at least some traditional AV scanners.  This reminds us again of the need to have a multi-layered defense.  Even something as simple as filtering EXE files at the gateway would have made this seeding event a non-issue.