writes "According to this story at Canada.com, the FBI, along with other authorities, have traced the origin of the Sobig worm. The quick timeline: Apparently, an earlier version of the worm installed a backdoor on a home computer in British Columbia. The creator of the worm used this compromised computer to create a Usenet account with Easynews.com in Phoenix, using a stolen credit card. The worm spread from Usenet, and contained the IP addresses of 20 computers to contact on Friday, and to download an unknown program from those computers. Officials were able to take 19 of these computers offline before the mass-download. However, the 20th computer stayed online, and many copies of the worm were able to get the rogue program. Those that did were merely redirected to a porn site, no damage done. However, now infected computers will continue to try and connect to the other 19 every Friday and Sunday until the worm expires on Sept. 10th."
points out this brief Reuters story
about the investigation, too.