According to Symantec;

Transmission through newsgroups
The worm will enumerate the registry looking for newsgroup server
addresses, then attempt to contact that newsgroup server. If no
newsgroup server is configured on the system, the worm will randomly
select one from a predefined list. The worm will download the
available groups and post messages to randomly selected groups. The
messages posted to the newsgroups are generated according to the same
routine utilized for email sending.

http://securityresponse.symantec.com/avcenter/venc/data/w32.swen.a@mm.html

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jurgen