Now, a new study by MIT researchers shows this isn’t such a far-flung idea. The scientists devised a method that allowed them to hack ambient light sensors, tiny components designed to adjust your screen’s brightness, to serve as a window to peer into our private lives. It’s the first time that someone has shown these sensors can essentially be turned into a second camera.

A hidden camera in disguise

At first glance, ambient light sensors appear harmless. They measure the brightness around you, automatically dimming your screen in sunlight or brightening it in darker settings for optimal viewing. However, the researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have found that these sensors can capture images of what’s happening in front of them, without the need for a camera. It’s a huge privacy risk that has remained under the radar until now.