Security experts have long urged vigilance against nefarious skimmers placed inside or on ATM machines. But a new generation of skimmers deployed by criminal elements may be even harder to detect.
Indeed, stealthy and "cleverly disguised" skimming devices capable of swiping card details and PINs are now being planted in close proximity - rather than inside - ATM machines.
"The most common skimmer can be found near cash machines located in the antechamber of a bank or building lobby, where access is controlled by a key card lock that is activated when the customer swipes his or her ATM card," explained security analyst Brian Krebs.
"In these scams, the thieves remove the card swipe device attached to the outside door, add a skimmer, and then reattach the device to the door. The attackers then place a hidden camera just above or beside the ATM, so that the camera is angled to record unsuspecting customers entering their PINs."
According to Krebs, criminals typically return later in the evening to retrieve the skimmers and encode the stolen data onto counterfeit cards, allowing them to easily withdraw money from compromised accounts.
"[One] incident [in California involved] a key card door lock [that was] stolen and modified a total of nine times in 2009.
"[And] bank security cameras at the scene of the crime [also] show [a] fake mirror installed over [an] ATM.
"Behind the glass was a battery-operated hidden camera. A tiny hole was cut out of the bottom of the mirror housing to enable the camera to record PIN entries."