As technology keeps evolving, hackers are also becoming masters in their acts. Today, researchers have said that hackers can silently steal sensitive information from air-gapped computers by manipulating the brightness of their screen by just three percent. This is according to researchers from Israel’s Ben-Gurion University of the Negev and the Shamoon College of Engineering.

The researchers showed how a piece of malware could collect valuable data from a device for example, passwords, encryption keys, files, modulate it in screen brightness, and transmit it to a nearby camera.

How it works

The researchers have proposed modulating harvested data by assigning a “1” value to a certain screen brightness and a “0” value to a different brightness; quickly changing the screen brightness results in a sequence of bits that can be captured by a camera pointed at the screen.

While it may seem that a screen whose brightness keeps changing would attract attention, the experts determined that it’s enough to change the red colour of each pixel by only three per cent. This small change in brightness is not visible to the naked eye, but it can be captured by a camera, which allows the exfiltration process to take place even while a user is working on the targeted computer.

The attack was tested using two displays – a 24″ PC monitor from Dell and a 40″ LED TV from Samsung-and three types of cameras, namely a Sony security camera, a Microsoft webcam, and the camera of a Samsung Galaxy S7 smartphone. The security camera and the webcam performed the same.

They captured data from up to 9 meters (30 feet) at a bitrate ranging between 5 to 10 bits per second. The smartphone camera only worked over distances of up to 1.5 meters (5 feet) with a bitrate of 1 bit per second. The researchers have pointed out that the room where they conducted the experiments only allowed for a maximum distance of 9 meters between the screen and the cameras, but the attack likely works over longer distances as well.

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