VSkimmer trojan steals card data on point-of-sale systems

Researchers have discovered a new trojan capable of stealing credit card data from point-of-sale (POS) systems, and it appears to be an updated version of Dexter, similar malware targeting card-swiping devices.

On Thursday, Chintan Shah, a security researcher for McAfee Labs, blogged about VSkimmer, which is capable of grabbing data – account numbers, expiration dates and service code numbers – stored on the magnetic strip of credit cards.

In the post, Shah also said the trojan targets Windows machines.

“The malware, vSkimmer, can detect the card readers, grab all the information from the Windows machines attached to these readers, and send that data to a control server,” Shah said.

McAfee researchers noticed participants on an online Russian forum discussing a potential sale, and began to analyze the trojan.

“The author of the thread also discusses other capabilities of this malware, which appears to be a successor of Dexter, but with additional functions,” Shah said.

Dexter was originally detected in December 2012 by researchers at Seculert, an Israel-based security firm. It too targeted POS terminals, devices swiped during purchases.

According to Shah, the fact that VSkimmer was targeting terminals running Windows showed how “financial fraud is actively evolving and how trojans are developed and passed around in the underground community,” he wrote.

In a Friday interview with, Adam Wosotowsky, messaging data architect at McAfee Labs, said that attackers likely started infecting machines with VSkimmer via USB devices.

“A USB [infection vector] would require an inside job or confidence scam – talking people into allowing you to [access] these machines,” Wosotowsky said.

McAfee has yet to confirm the number of infections. Its oldest sample of the malware dates back to February 13. Wosotowsky said, however, that efforts to leverage the trojan have been very “targeted,” so VSkimmer cases are likely not widespread.

“This is specialized malware, and it's a trend we are seeing more of – [attackers] going directly after point-of-sale systems,” he said. "There's a lot of activity moving in this direction."

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