Manufacturers and Traders Bank Corp. has developed an anti-skimming device, appropriately called the Blocker, to prevent card theft at its ATMs by making fraudsters' tampering blatantly obvious.

Fraudsters typically steal card data by attaching a well-camouflaged reader to an ATM's card slot. M&T's stainless-steel blocker works by making the real card-reader too bulky to modify discretely.

"If the criminal tried to attach a skimmer, which can look exactly like an ATM card reader, to the Blocker it would stick out so far it would be completely obvious it was not the real reader," says Blocker inventor Caroyln Criscitiello, M&T Bank's vice president of alternative banking and retail services.

Over a four-month period that started in July, Criscitiello developed the Blocker concept and worked with Bear Metal Works Inc. of Buffalo, N.Y., to manufacture the patent-pending product for installation on the ATMs, she says.

M&T, which is also based in Buffalo, has attached the Blocker to its 400 Diebold Inc. ATMs, but the device fits on any brand of ATM, Criscitiello says.

"It's a simple solution for all ATMs — just a coated steel plate that serves like a shield for the card reader," Criscitiello says. "People using an ATM probably won't notice a difference because the Blocker never touches the card."

Criscitiello would not disclose the cost to manufacture the Blocker or what the bank expects to charge others for the device.

However, the bank's research determined the Blocker would cost 1% of the expense of other advanced fraud-protection options available for ATMs, such as locks, cameras and software programs, she says.

"We would like to stop fraud in the industry by making the Blocker available to others," she says. "This is brand new; there is nothing else like it on the market, which is why we were able to file for a patent."

However, no single fraud-protection device will ever supply all of the answers for ATMs or other banking services, says Julie Conroy McNelley, senior analyst and fraud expert with Aite Group.

Blockers on ATMs will help stop some fraud, but banks always should use a layered fraud-prevention approach that relies on more than one defense mechanism, she says.

Aite cybercrime research suggests skimming ranks second behind malicious software as bank executives' greatest fraud concern, McNelley says. Fraudulent attacks on debit cards are three times more severe than on credit cards in overall "common point-of-purchase" losses, indicating ATM skimming remains a serious problem, McNelley says.

Many banks have an employee check ATMs at least once a day to ensure no skimming devices were placed on any of them, while others have installed a "jitter device" that shakes an inserted card enough to make it difficult for a skimmer to obtain the mag-stripe data, McNelley says.

Criminals placing skimmers typically target ATMs at bank branches on weekends, causing an estimated $50,000 in losses on average from a single weekend skimming attack, she says.