Several security firms are warning that a new version of the Bagle e-mail worm has appeared, and is spreading quickly. The worm, which now has some 80 known variants, first appeared in January of 2004 and has continued to mutate. This latest version, which has an empty subject line and body text, has probably been released so that its masters can harvest new e-mail addresses or bots for use in their nefarious activities.

Damage from the new Bagle variants should be minor as anti-virus vendors react quickly to the attacks, said Ken Dunham, director of malicious code at iDefense, another cybersecurity vendor. The first two variants were tentatively dubbed Bagle.CA and Bagle.CB, which would make them the 79th and 80th Bagle variants.

"We're a long way down the line of Bagle worms," Dunham said. "It's very similar to former Bagle attacks."