Scientists from two Israeli universities have come up with a way to use flatbed scanners as relay points when sending commands to malware installed on an air-gapped computer. Further research also revealed the scanner could also be used to relay stolen data to a nearby attacker.
The technique they come up with revolves around the idea that a beam of light could be interpreted as a binary 1 and the lack of visual stimulant can be considered a binary 0.
For this technique to work, two conditions must be met. First, the flatbed scanner lid must be left open in an upright position so an attacker can aim light beams at its sensors.