Security researchers have demonstrated that MacBook Pro keyboard audio can reveal what you are typing, with an accuracy of between 92% and 95%. They say the attack is a practical one on things like Zoom calls …
The attack relies on the different sounds made by different keys on the keyboard. Impressively, it was demonstrated on a MacBook Pro keyboard, rather than a noisier mechanical keyboard.
Bleeping Computer says that an attacker would first need to calibrate their data to your specific keyboard, but notes that this may be perfectly practical during video calls where participants also type messages into a group chat.
The first step of the attack is to record keystrokes on the target’s keyboard, as that data is required for training the prediction algorithm. This can be achieved via a nearby microphone or the target’s phone that might have been infected by malware that has access to its microphone.
Alternatively, keystrokes can be recorded through a Zoom call where a rogue meeting participant makes correlations between messages typed by the target and their sound recording.
The researchers gathered training data by pressing 36 keys on a modern MacBook Pro 25 times each and recording the sound produced by each press.
It could also work when people are combining video calls with things like Slack chatrooms.
With a malware attack, where an attacker can hijack a smartphone microphone to record audio locally, accuracy was 95%. When recording the keyboard over Zoom, it fell remarkably little, to 93%. Skype audio reduced accuracy slightly more, to 91.7%, but this still proved perfectly usable.
The researchers suggest altering your typing style if entering a password or other sensitive data during a live call, but a simpler solution against most attacks would seem to be simply ensuring your microphone is muted when not speaking, and not typing anything sensitive while you are.
That wouldn’t approach against a malware attack, but if someone has managed to hijack your iPhone microphones, you have bigger concerns than them listening to your MacBook Pro keyboard audio …
Photo: Moritz Kindler/Unsplash
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