You know the LED light on your hard drive. You’ve probably seen it… Do you think computers that aren’t connected to a network are safe? Stuxnet proved for the first time that they can be hacked “over the air.” But other than that, does it seem completely safe to plug a USB drive into a computer that isn’t connected to the internet?
Security researchers from Ben Gurion University in Israel have demonstrated that if an attacker manages to infect a computer, they could steal data remotely using a camera that can read the hard drive's (HDD) LED light.
The computer LEDs flash when the drive is in the read and write stage, but data can also be transmitted optically.
As Wired reports, the malware the researchers devised can cause a HDD LED to flash 6,000 times per second. If these lights are visible from a window, a drone or a telescopic camera lens can capture the signals from some distance.
The researchers explain in a paper that data can be leaked from HDD LEDs at a speed of 4kbps. Yes, the speed is incredibly slow by today's standards, but it's enough to steal all the encryption keys.
The “good thing” about this attack is that the HDD LED lights are blinking anyway, so no one can tell if the infected system is transmitting data.
It should be mentioned that with other malicious programs, researchers have managed to intercept data from unconnected computers through computer speakers, FM waves, and heat.
The coding system used to transfer data from HDD LEDs is called on-off keying, which is one of the methods of communication via visible light.
The researchers used a Nikon DSLR, a high-end security camera, a GoPro Hero5, a Microsoft LifeCam, a Samsung Galaxy S6, Google Glass, and a Siemens Photdiode sensor to steal data.
The Siemens sensor was the fastest at transferring data (4kbps), while the Galaxy S6 and GoPro Hero5 had bandwidths of 60 bits per second and 120 bits per second, respectively.
Fortunately, there are inexpensive methods to counter this attack. Covering the LED or disconnecting it, or moving the computer away from windows.
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