Source: http://www.engadget.com/2014/07/07/bank-skimmers-virtually-invisible/
Bank machine skimmers, which swipe your account as you insert your card, have been getting increasingly harder to spot as the years go by; now, it looks like they're just about undetectable. Researchers at the European ATM Security Team have found skimmers that not only fit neatly into a card slot, but do a good job of hiding any other equipment they need to steal your info. One example (shown below) combined a virtually invisible skimmer with a cleverly hidden spy camera that recorded PIN code entries. Another disguised a system that captured card info through audio, and there are now translucent mini-scanners that even a keen eye might miss.
These surreptitious gadgets may not go away for a while, either. While a number of major countries have moved on to chip-based card verification, Americans will still be relying on old-fashioned magnetic stripes for a long time. Until then, there's no guarantee that the ATM you visit will be entirely safe, no matter how good you are at noticing discrepancies. However, you can thwart many camera-equipped skimmers simply by covering the keypad when you enter your PIN -- thieves can't take what they can't see.
[Top image credit: AP Photo/Peter Dejong]
Source: Krebs on Security