"Invisible" laser helped a hacker determine from a distance what a MacBook user was typing

White hat hacker Sami Kamkar, who runs the YouTube channel Applied Hacking, has attempted to enhance a long-known technology to detect what a MacBook user is typing from a distance using an infrared laser, all without a direct line of sight to the keyboard.

The principle of using a laser beam to detect and decode sound waves has been demonstrated for some time: for instance, systems could easily determine what people were saying behind glass. However, it has also proven effective for identifying text being typed by a user at a distance.

Kamkar directed a beam through glass to the back of the MacBook, where he recorded the vibrations in the casing caused by key presses and then sought to decode them.

Sami mentioned that he first planned to create his own laser-based spying setup 15 years ago after watching a presentation by two hackers who demonstrated basic keystroke detection using a laser aimed at a laptop from across the room.

“It blew my mind,” says Kamkar. “But I also wanted to improve the system. Could I replicate the hack from outside, firing the laser from afar — and do so without being detected?”

In the end, he succeeded, although the results were not completely perfect. Screenshots reveal the text typed by the user and the text captured by the system:

The MacBook turned out to be an ideal target for the attack, as the hacker benefited from a high-quality reflective surface provided by the almost mirror-like Apple logo.

Source: 9to5mac, Wired