Using a computer monitor as a radio transmitter!

[lost_soul]

Some of you may have noticed at one point or another that a monitor can generate interference with an AM radio. People can actually manipulate the thing to

though... but it goes even further than this. Supposedly, you can remotely VIEW the contents of a display just by receiving these signals and interpreting them some how. Apparently this scientist Van Eck presented research and demonstrated this back in the 1980s. Here is some more information on it.

 

I've made the mistake of connecting an RCA video cable to a speaker input in the past, and the result was a hum... so could one actually remotely "recover" the signal from one of these displays?

[jaxa]

https://techrising.wordpress.com/tag/keyboard-espionage/

[Midnight]

It's even older than that, certain governments have been easedropping on (or at least known about) display emanations since the 60's, and many installations require a TEMPEST rated physical shielding to prevent these emanations from leaking. Here's a bit of info for those interested: Tempest

 

Another cool easedropping technology is using a laser to listen in on conversations by recording vibrations on objects / windows: Laser microphone

Edited September 2, 2011 by Midnight

[stumpy]

one of the places I worked at had shielding and were hardened against a emp attack on the monitors, bloody heavy things to move, took two people to move them, the towers were also shielded as well, it was also a closed network. the shields were thick sheets of alluminium with holes in the sheets, it was the holes that blocked the transmissions as the wavelength was too big to go through the holes.

 

another place I worked at doing simular type of work, non of their equipment was shielded, when I ask why they weren't using shield equipment I got a funny look, they had no idea what I was talking about.

 

with current wi fi, people can sit several yards away and hack into your wi fi signal and watch what you are doing, same with credit card readers, they can monitor the signals given off by a credit card reader and get your details, and hardened monitors dont seam to be used in government places any more, they've all switched to flat screen monitors, which also can be viewed with the right equipment from outside the building. plus you can also pickup signals from unshielded cables.

 

I noticed the other day that a local bar were using wi-fi tills, not going to use my credit card in there.

Edited September 2, 2011 by stumpy

[lost_soul]

Creepy... I just tried

on my LCD and I went and grabbed a small AM radio. Sure enough, I can hear it with the radio about 2 FT away. Of particular note is the last half of the video where he is panning his camera around. It makes the tones through the radio shift dramatically. Somebody could record this and then match the tones up, constructing a crude representation of what was on the original screen. The thicker bars tend to produce lower frequencies.

[lost_soul]

Also discovered the Timex Datalink the other day, which was a series of watches that came out in the 90s. One could send information to these watches through the use of a CRT monitor. The watch had what looks like an IR receiver at the top and they would be placed in front of the screen.

 

Demonstration: http://www.youtube.com/watch?v=tIvr850-EI0

 

It is odd because these aren't compatible with an LCD. I wonder if that is because of the way CRTs update the screen, or the generally worse contrast on LCDs, or something else?