It appears that whoever wrote Zotob had access to the Mytob source code, ripped out the email-spreading section, and plugged in the Microsoft exploit. It's possible that several people have access to the Mytob source code - so it may not be the last we see of this Internet scourge.
It appears whoever wrote Zotob had access to the Mytob source code, ripped out the email-spreading section and plugged in the Microsoft exploit.
In this case it appears that they were being used primarily for displaying unwanted pop-up advertisements, filling the hacker's pockets with cash.
However, when examined by an experienced virus analyst the similarities become clear. It appears that whoever wrote Zotob had access to the Mytob source code, ripped out the email-spreading section, and plugged in the Microsoft exploit.