They bought a Galileo CompuSafe on eBay. The most egregious problem they found is a fully functional USB port on the side of the safe. That allowed them to plug in a keyboard and a mouse, which worked.

The CompuSafe has a nine-inch touchscreen that runs an application that is used for entering authentication credentials. They found a way to escape that application -- known as a kiosk-bypass attack -- through a help menu, gaining access to the backend Windows XP embedded operating system.

At that point, it was game over for the safe. Petro and Salazar had administrator access to a Microsoft Access database file, which retains information on how much money the safe contains, user accounts on the system, when the door has been opened and other log files.

"By just editing that file, you can make the safe do anything you want," Salazar said.