[New air-gap jumper covertly transmits data in hard-drive sounds]

"DiskFiltration" siphons data even when computers are disconnected from the Internet.

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"The method has been dubbed "DiskFiltration" by its creators because it uses acoustic signals emitted from the hard drive of the air-gapped computer being targeted. It works by manipulating the movements of the hard drive's actuator, which is the mechanical arm that accesses specific parts of a disk platter so heads attached to the actuator can read or write data. By using so-called seek operations that move the actuator in very specific ways, it can generate sounds that transfer passwords, cryptographic keys, and other sensitive data stored on the computer to a nearby microphone. The technique has a range of six feet and a speed of 180 bits per minute, fast enough to steal a 4,096-bit key in about 25 minutes."
"The most effective way to prevent DiskFiltration-style data exfiltration is to replace hard drives with solid-state drives, since the latter aren't mechanical and generate virtually no noise. Using particularly quiet types of hard drives or installing special types of hard drive enclosures that muffle sound can also be an effective countermeasure. It may also be possible to jam hard-drive signals by generating static noise. Intrusion prevention systems may also be programmed to detect suspicious hard-drive seek patterns used to create the transmissions. Yet another solution is to isolate air-gapped computers from smart phones and other devices with a microphone."

Read more at arstechnica.net!