Protect Your Credit Card By Building a Skimmer Detector with a Raspberry Pi

Credit card skimmers are so effective because they’re very simple. Usually, they’re small modules that are connected to the magnetic stripe reader on a machine that you actually want to use. When you slide your card, you inadvertently pass the data through the skimmer as well, and unknowingly give away your credit card information. One of the most common places for skimmers to be placed is on gas pumps, and Tyler Winegarner has a device you can build to detect them and protect yourself.

Winegarner’s design is built on the earlier work of SparkFun Electronic’s Nathan Seidle, and both rely on identifying credit card skimmers by their Bluetooth names. Not all skimmers use Bluetooth, but it’s a popular choice because the black hat hacker who is trying to steal your credit card information doesn’t have to physically touch the skimmer after it has been placed in the gas pump. That reduces the chances of them getting caught, but the skimmers themselves tend to just use a few unique Bluetooth names, which can be cataloged and detected.

The research done by Winegarner, and Seidle before him, shows that these skimmers usually have a name like HC-03, HC-05, or HC-06. So, Winegarner’s solution was to use a Raspberry Pi Zero W to scan for those names every 10 seconds. If one of them is found, it gives you a warning on a small OLED screen. The device, when placed in a 3D printed enclosure, is small enough to sit unobtrusively in your car. All you have to do is glance at it when you pull up to a gas pump to make sure there aren’t any skimmers with those names within Bluetooth range.