Researchers discover how to steal data via WiFi from computers that… don’t have WiFi

In computing, we call air-gapped the computers that are on a separate network from the internet, so that they can store highly sensitive information without the risk of suffering from the threats we find on the web. It is an interesting strategy and one that has proven to be effective for a long time; however, the scenario has just changed after a discovery by an Israeli researcher.

Dr. Mordechai Guri, head of Research & Development at the Cyber ​​Security Research Center at Ben-Gurion University of the Negev, designed a very creative attack that he called AIR-FI. The idea is to filter data from air-gapped computers even if they are not connected to a WiFi network and do not even have the necessary hardware (receiving antennas) to receive such signals.

How is it done? Well, Mordechai found a way to use the DDR SDRAM rails (responsible for connecting the RAM sticks to the main controller of the machine) so that they emit electromagnetic waves at the frequency of 2.4 GHz, which, coincidentally, is the same used by most WiFi networks today.

Using another malicious device, he can then intercept such waves and decode the processed data and transmitted on that frequency; from there, just send the “gold” to a remote command and control server. The entire technical explanation of the attack was published in a scientific article called “AIR-FI: Generating Covert Wi-Fi Signals from Air-Gapped Computers”.

This is not the first time that the Israeli researcher has discovered curious methods to steal data from air-gapped machines – in May of that same year, he demonstrated the POWER-SUPPLaY attack, which transformed the target computer’s energy sources into a kind of speaker to transmit sensitive data at frequencies inaudible to humans.

Obviously, there are not many reasons to despair, since, in both hypothetical situations, the attacker would need to be very close to the isolated machines to be able to intercept the data. Still, studies show that air-gapped computers are not as safe as we all thought.

Source: arXiv, The Hacker News