User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6b) Gecko/20031205 Thunderbird/0.4
Uses the Mydoom backdoor to upload itself (over Mydoom ports).
Seeded over the weekend, it is out now and spreads fast.
Blocking: block Mydoom ports.
Gadi Evron.