'Ruthless' Trojan steals 500K bank, credit card log-ons

Russian gang kept 'extraordinary' malware on the prowl for nearly three years

A sophisticated cybercrime group that's maintained an especially devious Trojan horse for nearly three years has stolen the log-ons to more than 300,000 online bank accounts and almost as many credit cards during that time, a security company said today.

Researchers at RSA Security's FraudAction Research Labs tracked the Sinowal Trojan, also known as Mebroot and Torpig, to a drop server that contained the stolen credentials, said Sean Brady, the product marketing manager for RSA's ID and access assurance group.

"The sheer enormity of this makes this unique," said Brady. "And the scale is very unusual." All told, the gang behind Sinowal managed to obtain access to nearly half a million bank accounts and credit cards, a volume RSA dubbed "ruthless" and "extraordinary."

"And the fact that the Trojan was managed by one group through its history, and maintained for nearly three years is also very unusual," Brady said. RSA uncovered records that showed the Trojan had been in active operation since at least February 2006. "In malware life cycles, that's ancient, and to keep it up required a high degree of resources and effort."

The company's researchers first got onto Sinowal's trail after they captured a sample of the Trojan. An analysis of its code laid out a map back to the drop server. That server was another unusual characteristic of the malware. "Infection points and drop points go up and down all the time," Brady said. "They typically have very short life spans. But this drop site not only stayed up, it showed a sustained collection of log-ons."

Brady also credited Sinowal's longevity to its authors' skills and secrecy.

The Trojan has been revised more or less constantly, although there were periods when its creators ramped up the number of variants. After a lull last February, for example, the number of different versions again spiked in June, then hit slightly-lower peaks in August and this month.

The group is also more secretive than most, a trait that served it well. "They don't outsource," said Brady, "and [they] have all the necessary expertise in-house. They don't open their toolkits to other hackers, either. We suspect that the closed-loop nature of the group contributed to their ability to remain undetected."

These crooks, like many at the top rungs of the cyber underworld, work their craft first and foremost as a business. "We see some evidence that they have employed some practices that you may normally find in businesses that maintain high availability [of IT]," Brady continued. "They're using some redundancy, some backup effort for the data. They've clearly invested in this."

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More about BradyFinancial InstitutionsRSARSA, The Security Division of EMC

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