Inquiring minds in the federal government want to know whether Sobig.F actually made its first appearance last week on an adult Web newsgroup.
The FBI subpoenaed an unnamed Arizona Internet service provider before the weekend to help finding the instigator who first posted Sobig.F to the adult site in question, according to Reuters, which said Sobig.F's disguises included a link claiming a sexually-graphic image which infected the user's computer with the self-multiplying, self-spreading worm.
"Sobig.F was first posted to a porn Usenet group," said Network Associates research fellow Jimmy Kuo to Reuters, adding that Sobig.F infected as many as 100,000 computers and launched "millions upon millions of infected e-mails."
There were no further details available regarding this investigation as this story went to press.
Sobig.F spreads when a user opens a file attachment that comes with an e-mail with subject lines ranging from "Thank You!" to "Re: Details" or "Re: That Movie." If the attachment is opened, Sobig.F sends itself to e-mail addresses it takes from the infected computer and signs with random names and addresses from the computer's address book.
