Swidler said there's always the background thought that an enemy of a country could basically rent the botnet and launch a DoS attack, shutting down government agencies, utilities or financial centers. "It's a lot of computing power that could be focused to do a lot of damage," he added. "It's grid computing gone bad."

Last month, Ren-Isac, a collaboration of higher-education security researchers, sent out a warning that the Storm worm authors had another trick up their sleeves. The botnet actually is attacking computers that are trying to weed it out. It's set up to launch a distributed denial-of-service attack against any computer that is scanning a network for vulnerabilities or malware. The warning noted that researchers have seen "numerous" Storm-related DoS attacks recently.

MessageLabs' Sergeant said the botnet also has been launching DoS attacks against anti-spam organizations and even individual researchers who have been investigating it.

"If a researcher is repeatedly trying to pull down the malware to examine it the botnet knows you're a researcher and launches an attack against you," he said.

Lawrence Baldwin, chief forensic officer of MyNetWatchman.com, said he doesn't have a handle on how big the overall botnet has become but he's calculated that 5,000 to 6,000 computers are being used just to host the malicious Web sites that the Storm worm spam e-mails are linking users to. And he added that while the now-well-known e-cards and fake news spam is being used to build up the already massive botnet, the authors are using pump-and-dump scams to make money.

"That's pretty scary," he said. "Cumulatively, Storm is sending billions of messages a day. It could be double digits in the billions, easily."

Swidler said that since mid-July, Postini researchers have recorded 1.2 billion e-mails that have been spit out by the botnet. A record was set on Aug. 22 when 57 million virus-infected messages -- 99% of them from the Storm worm -- were tracked crossing the Internet.

According to researchers at SecureWorks, the botnet sent out 6,927 e-mails in June to the company's 1,800 customers. In July, that number ballooned to 20,193,134. Since Aug. 8, they've counted 10,218,196.