A researcher was able to exfiltrate data from air-gapped computers using vibrations produced by controlling the rotation speed of the machines’ internal fans.
Previously, researchers demonstrated that it was possible to exfiltrate data from air-gapped systems via heat emissions, HDD LEDs, infrared cameras, magnetic fields, power lines, router LEDs, scanners, screen brightness, USB devices, and noise from hard drives and fans.
The newly proposed technique relies on the fact that the entire structure on which a computer is placed is affected by the vibrations produced by the device’s internal fans, and uses sensors in modern smartphones to sense these vibrations.
In order to transmit data from networkless computers, researcher Mordechai Guri from the Ben-Gurion University of the Negev, Israel, has implemented AiR-ViBeR, new malware that can encode binary information and modulate it over a low frequency vibrational carrier.
The malware-generated vibrations can then be sensed and decoded by a malicious application on a smartphone placed on the same surface, such as an office desk. Because a mobile device’s sensors such as the accelerometer can be accessed by a malicious application even without asking for the user’s permission, the attack is highly evasive, the researcher argues.
“Our results show that using AiR-ViBeR, data can be exfiltrated from air-gapped computer to a nearby smartphone on the same table, or even an adjacent table, via vibrations,” Guri notes in a research paper (PDF).
To mount such an attack, an adversary would first need to compromise both the air-gapped computer (the transmitter) and the mobile phone of an employee (the receiver). The attack model also assumes that the employee carries the smartphone around the workplace.
Once the attacker was able to compromise the targeted organization’s environment, malware on the transmitter gathers information of interest, then encodes it and sends it to the environment via vibrations on the surface. The nearby infected smartphone receives the data, decodes it, and sends it to the attacker over the Internet.
The research mainly focused on the chassis fan, which produces the highest level of vibrations, but CPU and GPU fans can also be used. The AiR-ViBeR malware, the researcher explains, can manipulate the rotation speed of the chassis fan to create vibrations.
Data modulated on top of the vibrations is transmitted in small packets that contain a preamble header, a payload, and a parity bit. According to the researcher, data can be “exfiltrated at a speed of half a bit per second via the covert vibrations.”
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