Coming straight out of a spy movie, hackers can now exfiltrate sensitive data from an air-gapped computer by simply adjusting the screen brightness of a computer. What is an air-gapped computer? An air-gapped computer is one that is isolated from unsecured networks and is not connected to any other systems that is connected to the internet. It is also physcially isolated, meaning that data can only be passed in or out to it physcially. It is a procedure that is usually implemented in a high security environments such as military or banks.
So how does information get extracted from an air-gapped computer? Cybersecurity researchers have been able to demostrate an innovative way to covertly exfiltrate data by exploiting a computer’s emmission components such as light, sound, heat, radio frequencies, and even fluctuations in power currents. A computer infected with malware would encode the collected data as stream of bytes and then modulate it as binary 1 and 0 signals. In one case, the signals could be subtle changes in the computer screen brightness that is then captured by a compromised security camera.
https://thehackernews.com/2020/02/hacking-air-gapped-computers.html
Doan's Cybersecurity Blog 