W32/Mytob-HH is a mass-mailing, network and peer-to-peer worm for the Windows platforms. The worm also has an IRC backdoor component.

W32/Mytob-HH will harvest email addresses from the infected computer and then mail itself to those addresses as an attachment with extension ZIP.

W32/Mytob-HH also attempts to terminate a number of anti-virus and security related applications.

More information can be found at this Sophos page.