14 DAY TRIAL // Computer tech expert William Entriken has created a C library that can make a computer emit radio waves even if the device doesn't include any radio transmission hardware.
His program, called System Bus Radio, is written in C and relies on code that makes the computer's CPU emit electromagnetic radiation at certain frequencies.
The radiation is strong enough to escape the computer's shielding, and with the proper timing at which data is processed in the CPU, it can be forged into radio waves that carry off information away from the target's computer.
At the moment, the attack only works at a distance of two meters
During tests, Mr. Entriken says he managed to transmit a version of the "Mary Had a Little Lamb" song over a distance of up to two meters and one meter if a drywall separated the computer and the receiving antenna.
Mr. Entriken used a stock Sony STR-K670P radio receiver for his tests and explained he picked up the radio waves on the 1580 kHz on AM, but that this frequency may vary based on the distance from the target and the transmitting computer's hardware.
"Nobody has tried a fancy, directional antenna," Mr. Entriken told Softpedia. "This should be able to increase range up to 3 times."
"Also, nobody has tried amplification, we are all using VERY cheap equipment," the researcher also added. "It is possible we could [achieve] much better results with some fancier equipment. Different model[s] of computers give off different levels of radiation and so far nearly every one was able to get a signal."
EM radiations have been used in data exfiltration attacks before
For now, System Bus Radio is only a theoretical attack, but once more details are gathered and the algorithm is smoothened out, this can be a very complex method for exfiltrating data from an air-gapped computer.
In the past, other researchers have studied the possibility of using electromagnetic radiation to exfiltrate data from nearby devices. One such experiment was carried out only recently, when a group of researchers from the Tel Aviv University managed to retrieve an encryption key from a computer in another room, through the wall.
You can get System Bus Radio from GitHub, test it on your own hardware, and add your results to Mr. Entriken's findings. Below is a short video demonstration of System Bus Radio in action.
UPDATE: The article was updated to include some of the answers Mr. Entriken's provided Softpedia with via email.
