One of the two men arrested last week on charges of creating and mailing the Zotob bot worm also authored some, but not all, of the many Mytob worms in circulation, a security firm said Monday. Finnish anti-virus vendor F-Secure identified Farid Essebar, 18, who was arrested by Moroccan authorities, as the author of some Mytobs. "We know that [Essebar] had also authored several of the Mytob variants since February this year," F-Secure's Mikko Hypponen wrote on the company's blog. "However, he's not behind all of them."

Early analysis by others, including Ken Dunham, senior engineer with VeriSign iDefense, pegged Zotob and Mytob as close relations. "Hackers took the Mytob worm code and replaced the e-mail function in Mytob with the exploit of the MS05-039 vulnerability," said Dunham two weeks ago when the Zotob attack first began.

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