Researchers have configured two computers to talk to each other using a laser and a scanner.
Scanners work by detecting reflected light on their glass pane. The light creates a charge that the scanner translates into binary, which gets converted into an image. But scanners are sensitive to any changes of light in a room -- even when paper is on the glass pane or when the light source is infrared -- which changes the charges that get converted to binary. This means signals can be sent through the scanner by flashing light at its glass pane using either a visible light source or an infrared laser that is invisible to human eyes.
There are a couple of caveats to the attack -- the malware to decode the signals has to already be installed on a system on the network, and the lid on the scanner has to be at least partially open to receive the light. It's not unusual for workers to leave scanner lids open after using them, however, and an attacker could also pay a cleaning crew or other worker to leave the lid open at night.
The setup is that there's malware on the computer connected to the scanner, and that computer isn't on the Internet. This technique allows an attacker to communicate with that computer. For extra coolness, the laser can be mounted on a drone.
Here's the paper. And two videos.