If you’re carrying around an exposed circuit board and a bunch of wires people are going to notice you. But a dry erase marker won’t turn any heads. And this one holds its own little secret.

The hacking technique lays bare the security vulnerabilities of certain models of Saflok-brand RFID-based keycard locks used in 131 countries worldwide Erin Clack is a Staff Editor for PEOPLE.

The security flaws on this common hotel keycard lock are nothing short of face-palmingly stupid. Look closely at the picture above. This is a hotel room door swinging open. The device he holds in ...