How Do Skimmers and Shimmers Differ? What Credit Card Users Need to Know

Credit card skimming is nothing new, but newer devices called shimmers can steal more data than conventional skimmers. Here's what you need to know.

Modern credit cards come with a range of security features that help keep your financial details safe, like chip technology and tokenization. Criminals, however, use a variety of tricks to bypass these features and steal credit card info.

Skimmers and shimmers are two similar but distinct tools that criminals use to steal credit card details. This is a look at how they work, how they're different, and what the average consumer can do to protect themselves from these devices.

What Are Skimmers and Shimmers?

Skimmers and shimmers are small devices that criminals attach to ATMs, gas station pumps, parking payment machines, and other places where people swipe credit or debit cards.

Skimmers are older than shimmers and likely more common. These devices fit over the actual card reader and function in the same way—gathering information from your card's magnetic stripe when you swipe your card through the reader. However, unlike a legitimate card reader, the skimmer or shimmer funnels your card information to criminals. With this info, those criminals can effectively clone the card they scanned.

Certain security features make cards harder to dupe—like cards with chips that generate new payment information every time a person uses the card to make a payment. However, while skimmers can't steal chip data, newer data-stealing devices called shimmers can.

How Are Skimmers and Shimmers Different?

Shimmers are like skimmers but fit into the chip reader of a credit card terminal, between the terminal itself and a user's credit card. These devices are paper-thin and card-sized, making it easy for criminals to install them into a card slot.

Unlike skimmers, they capture chip data in addition to information from the card's magnetic stripe. Some devices can even gather your PIN and card number. The chip data that shimmers collect from cards is offloaded to criminals wirelessly via a small radio module built into the device.

Right now, these shimmers are still rare—the term "shimmer" was first coined just a few years ago, in 2018, by electronics retailer SparkFun. However, they're likely to become more common as criminals find ways to make the devices more inexpensively.

Protecting Yourself From Credit Card Shimmers and Skimmers

Simple precautions can go a long way in protecting your card info from both skimmers and shimmers.

If possible, limiting your use of physical cards can keep your info safe. Financial professionals note virtual cards offer several advantages over conventional credit and debit cards, like greater convenience and spending controls. They also prevent skimmers and shimmers from stealing your info. Without a physical connection, those devices can't grab information from your card.

Related: How a Criminal Can Use a Credit Card Skimmer Against You

When virtual cards aren't an option—or if you simply prefer physical cards—knowing how to spot a skimmer or shimmer will also help. Looking for signs like loose or unsecured card readers, different-looking card readers, and thicker-than-usual PIN pads can help you identify skimmers in the wild.

Know the Difference Between Skimmers and Shimmers

While your credit or debit card likely comes with security features that protect it from skimmers and shimmers, you're probably still vulnerable to these devices.

Using a virtual card or knowing how to spot skimmers and shimmers—as well as the differences between the two tools—can help you keep your card information safe from criminals.

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