Sinowal has infected hundreds of thousands of PCs worldwide during its run, and continues to attack machines. Once on a system, it waits for the user to enter the address to an online bank, credit card company site or other financial URL, then substitutes a fake in place of the real thing. It's triggered by more than 2,700 specific Web addresses, a massive number compared to other Trojans.
The fake sites collect log-on usernames and passwords to banks and other financial institutions, and also dupe users into disclosing information those organizations never collect online, such as Social Security numbers. The Trojan then transmits the stolen credentials and data to the drop server.
"This is one of the more sophisticated pieces of malware out there," said Brady.
One reason Sinowal has been so successful is that it's rarely detected by anti-virus software. "They struggle to find this one," Brady said. That's not surprising: the Trojan includes rootkit elements that infect the PC's master boot record (MBR), the first sector of a hard drive. Because the hardware looks to that sector before loading anything else, Windows included, the Trojan is nearly invisible to security software. Security vendors have complained for months about how tough the malware is to spot.
RSA suspects that the group responsible for Sinowal is based in Russia. "The distribution was truly global, but the one statistical anomaly that we noticed was Russia was the one region that had no infections." Cyber crooks will often forgo infecting machines in their own country in the hope that local law enforcement will not come calling, or if they do find out about the attacks, will put any action low on their priority list.
"This is the biggest find we've made to date," confirmed Brady. "But one reason why we're talking is so we can connect to [the affected] financial institutions." RSA has notified authorities and the banks and credit card companies with which it has existing relationships, but needs help in contacting others, he said.