Data theft via screen brightness modulation
At Ben Gurion University in Beer Sheva, a team of researchers at Mordechai Guri's lab showed a new way of stealing data from computers not connected to a network. The group, which has been investigating attacks on air-gapped systems for many years, has used the modulation of screen brightness this way.
They showed how an infected computer can change the screen brightness slightly so that the user doesn't notice it. At the same time, this is sufficient to allow the remote camera to detect changes and the algorithm to output modulated data. The most effective is changing the brightness of red pixels, where a three percent change is sufficient. The human eye does not detect this due to the rapid refresh of the image, but simple webcams have no problems. Data can be transmitted at up to 10 bps.
The attack was called Brightness, and it works until the isolated system can be infected somehow. This is often the hardest part of breaking in, but not impossible. As Stuxnet has shown, most often it comes with USB keys, without even needing a malicious agent in the building. Unsuspecting employees can unknowingly tolerate the dirt on their keys, so it's only a matter of time before they can infect the system.
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