Security experts warn of nastier Sasser worm

Computer security experts warned on Wednesday that the Sasser worm could merge with earlier virus-like programs to wreak more havoc on the Internet, just as companies and PC users clean up from the last attack and authorities hunt for those responsible.

Since appearing on the weekend, the fast-moving Sasser computer worm has hit PC users around the world running the ubiquitous Microsoft Windows 2000, NT and XP operating systems, but is expected to slow down as computer users download anti-virus patches.

But Sasser could mutate by combining with the two-month-old Netsky worm, making it a launching pad for further Web attacks that would put it on par with Blaster, the destructive worm that appeared last year and used infected computers to attack Microsoft Corp.'s Web site.

For now, the more benign Sasser worm does its harm by duplicating itself and slowing down Internet connections.

"My expectation is that Netsky and Sasser variants will merge and become what we call one 'abundant threat' that attacks through e-mail and software vulnerabilities," said Jimmy Kuo, a research fellow at Network Associates Inc.'s McAfee anti-virus unit.