This is very off-topic for the forum, so I figured Iād just throw this in this thread. I know thereās several other radio nerds here (and security folks), thought you might find this interesting. Iāll put it in a drop down,
Fun security/radio project inside!
I learned today that using the TEMPEST vulnerability, itās possible to read the contents of a monitorās screen, wirelessly, using nothing but an SDR and an antenna. This works by decoding the RF leakage from the monitorās image processing circuits, and itās especially effective on older monitors and cheaper monitors (less shielding).
Obviously, being the proud owner of a HackRF, I had to give it a try. There only seems to be one program for decoding, TempestSDR. It was written in Java, and it was an absolute pain in the ass to get running. It took me a solid hour to get all of the libraries installed that it needed (it needed a whole MinGW installā¦). It also seems to only like windows, I couldnāt get it to run at all on my linux install with my HackRF in particular. It would launch, but no IO. However, I canāt give TempestSDR too much grief, itās the only program I know of that can do what it does.
You also have to first use another SDR program to find the frequency of the leakage, it should be somewhere around 400MHz (mine is ~355MHz).
For my antenna, Iām using a cheap dipole, although sadly I seem to have misplaced my shorter telescopic antennas for it
Ideally Iād have one roughly matched to the proper frequency, but this oneās too long. Regardless, itās good enough to get a basic image.
The range youāll get is dependent on how bad the monitor is. My antenna had to be basically touching the plastic casing of the monitor, but some people have had success from the next room over with some monitors.
I had a really hard time keeping a consistent lock on the signal (and it took me forever to get it to lock on at all), but I got it to work 
Next, I threw up some sensitive data, that no one should ever seeā¦
Totally readable.
While it messes up the tracking, pivoting the antenna can yield even clearer results for text:
Hereās the classic āIndian-head test patternā:
I hope someone else finds this as interesting as I did, it took me about 2-3 hours to get it working. Figured it was worth a post.
