Keyboard Lights As An Airgap Attack Vector

What do you do when you need to get data into an airgapped machine? Well, you might find yourself limited to basic input devices to interact with the computer in question. As [Nikolay Valentinovich Repnitskiy] demonstrates, though, you can do some fun stuff amidst such limitations.

[Nikolay] created what he calls a “unidirectional network” connection via a keyboard. Specifically, he took two Dell SK-8115 keyboards, and stripped them down to their controller PCBs. On one, he soldered photoresistors to a couple of the keyboard matrix pins, such that they’d fire a keypress when lit up.

He then placed the other keyboard PCB such that the Num Lock and Caps Lock LEDs are lined up with the photoresistors. This made it possible to have one PC flash the keyboard LEDs in order to “type” on the other machine. This can be used to move data on to it, such as a little program which [Nikolay] prepared which can be made executable and used to further break into the machine and make it easier to pull data across more efficiently in future.

We looked at an earlier version of this hack some time ago. If you’ve been imagining creative ways to talk to airgapped computers, be sure to let us know on the tipsline!