If you believe common wisdom, it shouldn’t be possible to take over most webcams without alerting users. The indicator LED is supposed to be hack-proof, after all. However, a pair of Johns Hopkins researchers have recently published a research paper showing that it’s possible to control the camera while keeping the indicator dark. Their proof-of-concept app, iSeeYou, reprograms a controller chip on pre-2009 Macs to separate the camera and LED functions; users can flick the light on and off like a switch. Apple is aware of the issue with its own systems, but it hasn’t said whether or not there will be a fix. It’s also unclear how many newer Macs or other PCs are at risk. Regardless of the exact threat, the study isn’t very reassuring in an era of widespread surveillance — if a pair of academics can stealthily record your activity, it’s likely that professional spies can do the same.