Screen brightness and computer hacking: two concepts that seem to go hand in hand

Following experiments in a cybersecurity laboratory, Israeli researchers have managed to demonstrate something quite exceptional.

Indeed, these computer security specialists have succeeded in setting up a computer hacking process that involves using different variations in brightness on LCD screens, in order to intercept digital information from a terminal.

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At the moment it is only at an experimental stage so not very elaborate, but what is sure this technique does work. For the technique used on a PC, for example, using the brightness of the screens, transmissions are limited so far to 5 bits per second, but can be up to 10 bits per second. The researchers behind this discovery are academics from the Ben-Gurion institution of higher education. He is Mordechai Guri, Dima Bykhovsky and Yuval respectively. And they proudly named their technique "Brightness,"

The technique is really impressive because it is not easy to use it. The principle seems to be simple but very complicated. it will consist for the hacker to capture in video, the different fluctuations in the brightness of LCD screens, something that in principle is imperceptible to the naked eye. Once the different fluctuations are detected, the researchers will then extract the different information associated with a set of algorithms, it will then be possible, to steal several documents on a system even if it is not connected to an Internet network. The technique has proven slow but very effective and in the face of a USB stick, discretion is truly assured. "Our experiments show that the best communication performance was to focus on the red color. In this modulation, we changed the red color of each pixel by a maximum threshold of 3%.

These changes are invisible to humans but can be reconstructed from a recorded video stream. With the security camera and webcam, we could reach binary speeds of 5 to 10 bits per second over a maximum communication distance of 9 meters. The resulting bit error rate (BER) was 0% for all experiments."The researchers explain. While in some sense the rates of captures appear to be low, it is still enough to steal some sensitive data such as identifiers or passwords. "The signal is modulated by imperceptible changes in one of the RGB components. Color changes are used for modulation and the camera is used for signal detection. the researchers note.

In addition, it should be noted that this is not the first time that researchers have been able to do this. It has previously had several trials that have worked and this seems to have become something quite classic. In addition to this new "BrightNess" technique, the same researchers have developed other methods to steal data or internet connection. Among them is the LED-it-Go (Activity LED of a hard drive).

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