Researchers from Hunan University, UC San Diego, and Michigan State University presented ESauron at USENIX Security ’24, a system that finds hidden spy cameras by listening for the electromagnetic radiation their memory gives off.

The idea rests on something every camera has to do. Raw images get encoded and compressed before they are sent anywhere or written to storage. That work happens in read-write memory, and the memory clock drives switching voltage regulator activity that varies with the workload. The result is EM radiation at the clock frequency.

When the scene in front of a camera changes, the encoder suddenly has more to do, and the EM signature jumps. ESauron triggers that on purpose by causing a scene change, then watches for the surge. Because it reads radiation and not network traffic, it works on wireless, wired, and offline cameras that record to a card.

Tested against 50 camera products, the prototype detected every one with 100% accuracy after four stimuli.…