FLIR One – Infrared Accessory is a new device that can be fitted into iPhone 5 and 5s cases which allows the camera to pick up thermal heat signatures which are then translated into thermal colour images. Although the device was created for security and detecting home repairs, thieves can use the device to detect thermal heat signatures left on ATM machine keyboards after people enter their PIN's.
The camera produces a thermal colour image of the heat left on ATM buttons by user's fingertips, and using the image, thieves can detect which numbers make up the PIN, and which order the numbers were typed in. With just a PIN, thieves can take other details from cards using a radio frequency identification scanner, which uses electromagnetic fields to transfer data.
This isn't the first mention of thermal imaging being used for illegal activity; in 2011, USENIX Security Symposium revealed that thermal imaging can detect left-over heat from key presses. Volunteers selected random numbers on metal and plastic PIN pads, and it was found that the plastic pad made it possible to see heat signatures to determine the numbers pressed and the order they were pressed in.
It is, however, possible to protect yourself from your PIN being stolen this way: rest a few fingers on other buttons whilst typing your PIN, making it harder to detect which numbers were used, let alone the order.