"Researchers Transmit Data Covertly by Altering Screen Brightness"

Researchers at Ben-Gurion University (BGU) of the Negev have demonstrated a new way to extract data from air-gapped computers, which involves altering the pixel density of these computers' LCDs. Air-gapped computers refer to systems isolated from the internet due to its containment of highly sensitive information. Other methods of stealing data from air-gapped computers that have been discovered by BGU researchers, involve using speakers, blinking LEDs in PCs, infrared lights in surveillance cameras, and computer fans. In a recently published paper, the researchers described a covert optical channel that can be detected by cameras, but not users. The idea is to transmit the information by changing a screen's brightness in a sequential pattern. A camera would be used to capture the compromised computer's screen. This article continues to discuss the method discovered by BGU researchers that can be used to covertly transmit data from an air-gapped computer, the limitations of this technique, and other methods developed by researchers to communicate with such computers. 

Naked Security reports "Researchers Transmit Data Covertly by Altering Screen Brightness"