At least three new variants of the damaging Sober worm are circulating on the internet.
Security software companies including F-Secure, Kaspersky Lab and others say the worm, which first appeared in 2003, is continuing to mutate in an attempt to crash networks.
Once the attachment is clicked, Sober is unleashed and spreads itself through users’ address books while spreading spam e-mail and rapidly crashing networks due to the huge traffic it creates.
The worm is also capable of erasing anti-virus software, leaving users powerless to disinfect their systems.
Kaperskey has identified the Sober.u, Sober.v, and Sober.w variants of the worm. In recent weeks, the worm has been used to spread fascist propaganda in Germany.