Crooks who make and deploy ATM skimmers are constantly engaged in a cat-and-mouse game with financial institutions, which deploy a variety of technological measures designed to defeat skimming devices. The latest innovation aimed at tipping the scales in favor of skimmer thieves is a small, battery powered device that provides crooks a digital readout indicating whether an ATM likely includes digital anti-skimming technology.

A well-known skimmer thief is marketing a product called “Smart Shield Detector” that claims to be able to detect a variety of electronic methods used by banks to foil ATM skimmers.

The device, which sells for $200, is called a “Smart Shield Detector,” and promises to detect “all kinds of noise shields, hidden shields, delayed shields and others!”

It appears to be a relatively simple machine that gives a digital numeric indicator of whether an ATM uses any of a variety of anti-skimming methods. One of the most common is known as “frequency jamming,” which uses electronic signals to scramble both the clock (timing) and the card data itself in a bid to confuse skimming devices.

“You will see current level within seconds!,” the seller enthuses in an online ad for the product, a snippet of which is shown above. “Available for sale after November 1st, market price 200usd. Preorders available at price 150usd/device. 2+ devices for your team – will give discounts.”

According to the individual selling the Smart Shield Detector, a readout of 15 or higher indicates the presence of some type of electronic shield or jamming technology — warning the skimmer thief to consider leaving that ATM alone and to find a less protected machine. In contrast, a score between 3-5 is meant to indicate “no shield,” i.e., that the ATM is ripe for compromise.

KrebsOnSecurity shared this video with Charlie Harrow, solutions manager for ATM maker NCR Corp. Harrow called the device “very interesting” but said NCR doesn’t try to hide which of its ATM include anti-skimming technologies — such as those that claim to be detectable by the Smart Shield Detector.

“We don’t hide the fact that our ATMs are protected against this type of external skimming attack,” Harrow said. “Our Anti-Skimming product uses a uniquely shaped bezel so you can tell just by looking at the ATM that it is protected (if you know what you are looking for).”

Harrow added that NCR doesn’t rely on secrecy of design to protect its ATMs.

“The bad guys are skilled, resourced and determined enough that sooner or later they will figure out exactly what we have done, so the ATM has to be safe against a knowledgeable attacker,” he said. “That said, a little secret sauce doesn’t hurt, and can often be very effective in stopping specific attack [methods] in the short term, but it can’t be relied on to provide any long term protection.”

The best method for protecting yourself against ATM skimmers doesn’t require any fancy gadgets or technology at all: It involves merely covering the PIN pad with your hand while you enter your PIN!

That’s because the vast majority of skimming attacks involve two components: A device that fits over or inside the card reader and steals data from the card’s magnetic stripe, and a tiny hidden camera aimed at the PIN pad. While thieves who have compromised an ATM you used can still replicate your ATM card, the real value rests in your PIN, without which the thieves cannot easily drain your checking or savings account of cash.

Also, be aware of your physical surroundings while using an ATM; you’re probably more apt to get mugged physically than virtually at a cash machine. Finally, try to stick to cash machines that are physically installed inside of banks, as these tend to be much more challenging for thieves to compromise than stand-alone machines like those commonly found at convenience stores.

KrebsOnSecurity would like to thank Alex Holden, founder of Milwaukee, Wisc. based Hold Security, for sharing the above video.

Are you fascinated by skimming devices? Then check out my series, All About Skimmers, which looks at all manner of skimming scams, from fake ATMs and cash claws to PIN pad overlays and gas pump skimmers.

Tags: alex holden, Charlie Harrow, Hold Security, NCR Corp, Smart Shield Detector