At the core of the AIR-FI technique is the fact that any electronic component generates electromagnetic waves as electric current passes through.
Since Wi-Fi signals are radio waves and radio is basically electromagnetic waves, Guri argues that malicious code planted on an air-gapped system by attackers could manipulate the electrical current inside the RAM card in order to generate electromagnetic waves with the frequency consistent with the normal Wi-Fi signal spectrum (2,400 GHz).
In his research paper, titled “AIR-FI: Generating Covert WiFi Signals from Air-Gapped Computers,” Guri shows that perfectly timed read-write operations to a computer’s RAM card can make the card’s memory bus emit electromagnetic waves consistent with a weak Wi-Fi signal.
This signal can then be picked up by anything with a Wi-Fi antenna in the proximity of an air-gapped system, such as smartphones, laptops, IoT devices, smartwatches, and more.
It looks like you’d need a friendly within feet of the corrupted system, or a dupe carrying a smartphone, laptop, etc, that had also been corrupted.
Still, a fascinating hack.