"LF Electromagnetic Radiation Used for Stealthy Data Theft From Air-Gapped Systems"
Mordechai Guri, a cybersecurity researcher from the Ben-Gurion University of the Negev in Israel who specializes in air gap jumping, has recently released a paper detailing yet another method that can be used to stealthily exfiltrate data from systems isolated from the internet and local networks. The researchers stated that the new method involves using the dynamic power consumption of modern computers and manipulation of CPU loads in order to cause the device to generate specific low-frequency (LF) electromagnetic radiation in the 0-60 kHz band. Guri was able to show how a malicious actor who has managed to plant a piece of malware on the targeted device can exfiltrate small pieces of highly sensitive information, such as passwords or encryption keys. The researcher demonstrated that the attack can be conducted over distances of 2 meters (6.5 feet) and even more. The attack method has been named COVID-bit because this distance is often recommended for preventing Covid-19 transmission. Guri noted that the malware planted on the air-gapped computer can cause the device to generate a certain frequency to represent a "1" bit and a different frequency for a "0" bit. The transmitted data can then be captured from a short distance, including through a wall, by a smartphone or laptop that has been fitted with a $1 antenna that can be hidden inside a case or within harmless-looking objects such as headphones. Guri noted that the smartphone records the frequency and translates it to the corresponding "0" or "1" bit. In addition to the actual payload that is being exfiltrated, the attacker can add calibration bits and bits used for error detection, which leads to a reduction in speed, but makes the exfiltration channel more reliable. The researchers stated that experiments showed that the COVID-bit attack can achieve data transmission rates of up to 1,000 bits per second, which would allow an attacker to exfiltrate a Bitcoin private key in less than a second and a 4096-bit RSA encryption key in 4 seconds. The researcher noted that keylogging can be conducted in real time.