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An Anonymous Coward writes:

https://www.rtl-sdr.com/trojpix-covertly-transmitting-data-from-air-gapped-systems-via-video-cable-emissions/ [rtl-sdr.com]

Researchers from the University of Shandong have recently demonstrated in a paper [usenix.org] that they can transmit data from an air-gapped PC by using a Trojan to implement imperceptible pixel modulation in a monitor.

Every electronic device unintentionally emits RF, and PC monitors, TVs, and screens are no exception. In the past, we have shown [rtl-sdr.com] that with simple TEMPEST tools, it is easy to recover the image on a screen over a distance using an RTL-SDR or Airspy SDR.

TrojPix relies on the unintentional emitted RF from a PC monitor's video cable. By subtly modulating the pixels on a screen, it is possible to enable data transfer via the unintentional emissions. This means that any PC infected with the TrojPix Trojan could transfer data wirelessly to a snooper, even if the PC is totally disconnected from any wired or wireless network. The only way to stop such an attack would be to completely shield the PC with a faraday cage.

The team note that they were able to achieve a peak data throughput of 8.1 MBps over a max range of 208 meters. They tested nine commercially available monitors and fifteen digital video cables, each demonstrating significant usable RF leakage.

The receiver hardware used was a USRP X310 software-defined radio sampling at 10 MHz and the transmissions appear to have been at 148.5 MHz and 297 MHz.

Original Submission