Instant message worm attacks increasing

Experts warn users to be wary of links sent over IM

By Bob Sullivan
Technology correspondent

Updated: 9:09 p.m. ET March 7, 2005A spate of instant message worms released over the last few days has some antivirus researchers concerned: With e-mail viruses less effective than before, virus writers, they say, are now turning their attention to the popular and not very secure chat tools used by millions.

A worm named Kelvir made the rounds on Sunday, with several variants appearing almost immediately.

Kelvir is tricky, pasting a simple message in Microsoft's MSN Messenger chat tool, such as "lol! See it! You'll like it!" The worm then displays a link to a Web page infected with a Trojan horse. Users who click on the link are infected with the worm. Not only do they then send copies of the worm to fellow chatters, a Trojan horse is also installed on their systems.

The ploy is effective because it can appear in mid-conversation with another chatter, convincingly suggesting it's really from someone you are talking to.

"This is a fairly big deal," said John Sakoda, the chief technology officer at IMLogic, an instant message security firm. He said more than 10 percent of his firm's 400 clients reported seeing a variant of Kelvir in recent days.

None of the variants will cause a serious outbreak, antivirus firms say, because they involve two steps to infect users they must see the file name, and then click on a Web site link. Once that Web site is removed from the Internet, the worm no longer operates, and all the Kelvir Web pages have been pulled down.

Still, researchers are worried that virus writers have taken a fancy to IM tools, and expect to see many more worms targeting the tools in the coming months. Already, there have been as many IM worms this year alone as there have been in all the years previous, said antivirus guide Mary Landesman.

"The underlying point is instant message worms are gaining a lot of speed. There is a lot of activity right now," said Craig Schmugar, a virus researcher at "There is definitely a shift in the attention of at least some virus authors."

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