Signature-based technologies are now "crumbling under the pressure of the number of attacks from cybercriminals," said Art Coviello, president of RSA Inc., the security division of EMC Corp. This year alone, about 200,000 virus variants are expected to be released, he said. At the same time, antivirus companies are, on average, at least two months behind in tracking malware. And "static" intrusion-detection systems can intercept only about 70 percent of new threats.

"Today, static security products are just security table stakes," Coviello said. "Tomorrow, they'll be a complete waste of money. Static solutions are not enough for dynamic threats."

What's needed instead are multilayered defenses -- and a more information-centric security model, Coviello said. "[Antivirus products] may soon be a waste of money, not because viruses and worms will go away," but because behavior-blocking and "collective intelligence" technologies will be the best way to effectively combat viruses, he said.

Unlike the low-variant, high-volume threats of the past, next-generation malware is designed explicitly to beat signature-based defenses by coming in low-volume, high-variant waves, said Amir Lev, president of Commtouch Software Ltd., an Israeli vendor whose virus-detection engines are widely used in several third-party products.

Until last year, most significant e-mail threats aimed for wide distribution of the same malicious code, Lev said. The goal in writing such code was to infect as many systems as possible before antivirus vendors could propagate a signature. Once a signature became available, such viruses were relatively easy to block.