Those groups, most based outside the United States, are now well-funded and well-organized, with technology experts working side by side with old fashioned scammers and "mules" or foot soldiers, Crooks said.

"Nobody is doing anything about them," Crooks said. "We can put up walls and swamps, but nobody is going after them," he said.

Although credit card fraud has been rampant online for years, checking and savings accounts have largely been spared. But that is changing.

A major security breach at an online retailer, reportedly OfficeMax, in 2005 led to the reissue of hundreds of thousands of debit cards by U.S. banks in early 2006, as well as sporadic reports of consumer debit card fraud and identity theft tied to that theft.

"Customers are more sensitive to their money being stolen from checking and savings accounts than from credit cards," Crooks said. "In the end, banking is a confidence game. If you don't have confidence in the [banking] channel, that's not good for a bank."