Year-old Storm virus still infecting PCs

Anti-spam experts in the United States predicted the year-old, constantly mutating Storm virus could send up to 500 million messages during the holiday season.

The virus, one of the nastiest and most persistent, has infected at least 1 million personal computers around the glove and e-mail managers said it is responsible for billions of unwanted e-mail -- spam -- clogging in-boxes.

"There does not seem to be any let-up in sight," Adam Swidler, a senior manager at Postini, an e-mail management company in San Carlos, Calif., told USA Today. "Storm is perfectly capable of virtually unlimited mutations."

Storm began its e-reign in November 2006 as Nuwar, an e-mail attachment claiming to be a story about a nuclear war between the United States and Russia but was a computer virus that hijacked the victim's PC, spitting out penny-stock-fraud spam. In December 2006, the attachment mutated into a New Year's greeting, with the same payload. In January, it was reborn Storm and carried an e-card linking to a tainted Web site.

Alone, none of the virus' techniques are innovative, experts said. But the mutations and morphing techniques keep it just out of the reach of anti-virus vendors.