'Rock Phish' blamed for surge in attacks

And just as browser makers have been building phishing filters into their products, the group has begun creating unique URLs for its phishing messages to get around blacklists of known phishing addresses.

These single-use URLS make it extremely difficult for antiphishing researchers to identify and block phishing pages, Symantec's Ramzan said.

This is bad news for products such as the Firefox browser, which uses a blacklist. "Ultimately, technologies that rely heavily on blacklists are going to be useless," Ramzan said.

Rock Phish has contributed to a surge in the number of phishing Web sites over the past few months, according the Anti-Phishing Working Group. In August, the group counted 19,000 phishing URLs. By October, the most recent month for which data is available, that number had nearly doubled to 35,000.

Security experts guess that Rock Phish is run by an extremely small group of technically savvy criminals -- probably about a dozen hackers -- who set up the phishing Web sites, manage the domain name registration and ensure that the stolen financial information is funneled into a central server, which researchers call "the Mother Ship."

This group then sells the credit card and banking information in Internet-based chat rooms to a much wider range of money launderers who actually extract money from these accounts, according to researchers who asked not to be identified.

Rock Phish uses a network of hacked computers to redirect Web visitors to the Mother Ship, and the group has been particularly adept at exploiting the decentralized nature of the Internet for its illegal activity. One successful trick has been to register new phishing addresses in little-used country domains -- São Tomé and Principe (.st) and Moldovia (.md) have been recent targets -- where law enforcement and phishing take-down groups may not have establish contacts, according to researchers.

During the time it takes to establish contacts with the domain name registrars and have them take down the fraudulent Web domains, Rock Phish can continue to collect information.

"They're the innovators in the phishing space," said Symantec's Ramzan. "Whenever there's a new technique that comes out, it can be traced back to the Rock Phish group."