As the MSBlast worm continues its spread--to approximately 2,500 new computers each hour--antivirus firms said Wednesday that a new variant had been released. Security company Symantec, which directly measures the spread of the worm via sensors distributed throughout the Internet, said the number of computers compromised by MSBlast--aka W32/Lovsan and W32.Blaster--had reached 228,000 by midmorning Wednesday. Alfred Huger, senior director of engineering for the company's security response team, estimated that millions of computers may still be vulnerable to the flaw, leaving administrators scrambling to patch systems before they fall victim to the worm's relentless spread.

"If people don't patch, there could be millions of infections," Huger said. Symantec and rival antivirus companies Network Associates, Kaspersky Labs and Central Command all warned users of a modified version of the worm that apparently differs by only a few file names but otherwise is identical to the original. Network Associates also discovered a third version of the worm that apparently changes a file name and a registry key.

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