Anti-virus companies are reporting the rapid spread of a new variant of the MyDoom worm, which targets users’ e-mail lists on their machines and uses their domains to make repeated searches through search companies such as Google.
Last summer MyDoom almost brought down Google as a result of millions of constant searches being generated by infected computers around the world, with the web’s overall performance also being affected.
Other search companies such as Lycos and Yahoo are also targeted by the worm.
Security companies Sophos, Symantec and others have already issued patches against W32/MyDoom-O, which also has aliases such as WORM_MYDOOM.M, I-Worm.Mydoom.m and W32/Mydoom.bb.
Sophos said the latest incarnation of MyDoom posed a "high" threat.