A group of researchers at Israel's Ben-Gurion University has come up with a novel way to extract information from a computer, even when it's disconnected from the internet. The technique is called DiskFiltration, a method for stealing data using the sounds of the hard drive.
How DiskFiltration works
This method takes control of the hard drive's read/write head, which operates similarly to the arm of a record player to read or write data. These movements generate sounds that transfer passwords, cryptographic keys, and other confidential data stored on the computer to a nearby microphone. In the video below, you can see how DiskFiltration works using a smartphone's microphone:
Technical details
DiskFiltration uses acoustic signals emitted from the computer's hard drive to collect data. The method has a range of two meters and a speed of 180 bits per second, which is fast enough to steal a 4096-bit key in about 25 minutes. It may seem too slow to gather such a small amount of data, but it's important not to forget that within it there may be very valuable information that could leave a user completely vulnerable. Additionally, it's worth noting that the computers targeted for data theft must already be infected with malware.
Another point to consider is that receiving data transmitted via sound generated from a hard drive is not very efficient. This is due to the occasional noise from other processes, which can sometimes interfere with or interrupt DiskFiltration transmissions.
How to protect yourself
If you want to prevent data leakage from your computer, the most effective way is to replace hard drives with solid-state drives, since the latter are not mechanical and generate practically no noise at all. Another option is to interfere with the signals emitted by the hard drive units by generating static noise, or to isolate computers from smartphones and other devices with microphones.
