Be sure to use caution when withdrawing cash from some automated teller machines.
NCR Corporation, a Georgia-based ATM manufacturer, has reported an uptick in "deep insert" skimming devices on ATM machines around the world, including countries such as the United States, United Kingdom, Greece, Ireland, Italy, Switzerland, Sweden, Bulgaria and Turkey.
Insert card skimmers are hidden inside of the card acceptance slot on a cash machine and are almost invisible to consumers.
In an alert sent to banks and customers, NCR said deep insert skimmers — usually made of metal or PCB plastic — are difficult to detect.
"Neither NCR Skimming Protection Solution, nor other anti-skimming devices can prevent skimming with these deep insert skimmers," the company wrote. "This is due to the fact the skimmer sits well inside the card reader, away from the detectors or jammers of [NCR's skimming protection solution]."
Charlie Harrow, solutions manager for global security at NCR, told Krebs On Security that earlier insert skimmers ran on watch batteries and used rudimentary wireless transmitters to send card data to a nearby base station.
The company believes that tiny pinhole cameras are used to record customers' PIN information, and can also be used as a receiver for the stolen card data sent by the skimmer inside the card slot.
According to Harrow, earlier skimmers were not designed to be retrieved due to the way card readers work on ATM machines.
"Usually what happens is the insert skimmer causes a card jam," he said. "These skimming devices can usually cope with most cards, but it's just a matter of time before a customer sticks an ATM card in the machine that is in less-that-perfect [sic] condition."
Newer models include tiny memory chips that hold private data skimmed off the cards. Harrow says this is preferable to sending data wirelessly because writing it on a memory chip saves more power from the coin battery.
While deep skimmers have very short duty cycles, they're also designed to be retrievable, according to Harrow.
"The ones I've seen will snap into some of the features inside the card reader, which has got various nooks and crannies," he said. "The latest ones also have magnets in them which are used to hold them down against the card reader."
