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Tempest, it uhhhh finds a way. (sh.itjust.works)
submitted 5 months ago by to c/cybersecuritymemes@lemmy.world
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I knew that it was possible to spy on CRT displays due to the signals they radiate, but apparently that is a problem with HDMI too.

Here a very interesting write up on how to extract frames from leaked RF from HDMI cables and using said RF to transmit a webcam stream even: https://www.windytan.com/2023/02/using-hdmi-radio-interference-for-high.html

Here a example of someone using HDMI RF to transmit LoRa signals: https://www.youtube.com/watch?v=HDbdAZd6cLw

This makes for a interesting attack vector for locating a user, if said user clicks on a video (or even a gif) that crafts LoRa frames to radiate from his HDMI and there is for example a Meshtastic receiver near by that relays those frames into a wider network.

There are ways to migrate this issue, for example using the encrypted version of HDMI usually used to enforce content copyright protection, or using a fiber optic HDMI cable (by now they are almost as cheap as the copper ones and are not restricted to a max lenght of 5m).

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[–] 12 points 5 months ago (2 children)

Close, the NES actually broadcasts a standard NTSC RF signal on its output. The old TVs were acting as a broadcast antenna for the others to pick up. You can do the same thing with some decent rabbit ears by just putting a paperclip into the center pin of the RF output on the side of the console. Don't play that way though, you would be technically operating a pirate TV station if you didn't have a license to broadcast on that channel. The NES should be a low enough output power that it doesn't matter either way.

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  • [–] 10 points 5 months ago* (1 child)

    Fun fact: before superheterodyne radios were invented, you needed a license to operate a radio including just to plug it in and tune it.

    The reason is simple regenerative radios back In the day were also transmitting a small amount of signal back when they were receiving a station. As a result, at least in the US you needed a radio operator's license to listen to a radio since you were technically transmitting.

    Super heterodyne radios fixed this though by having extremely levels of sensitivity and basically now backfeed signal transmitted.

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