Can surge strips be used for surveillance using electrical inductance ringing of building wiring?

[Dr.Strangelove]

@electronbee

Old paper but still relevant. Not too many use serial now a days but Ethernet waveforms are somewhat similar. I think at higher data rates this would become difficult.

The paper claims that data rates up to ~10 Mb/s should be possible, but also that the LAN cards they tested didn’t exhibit the problem. Of course, a 1-cent capacitor would solve the problem completely.

I’d be surprised if you could get a signal through a PSU with something as low powered as an LED (not to mention the data rate), but if you really had to smuggle a signal out of a building, I’ll bet you could run a program that ramps the CPU utilization up/down at a few bits per second, and have the result be detectable at the circuit breaker.

[Stranger_On_A_Train]

@engineer_comp_geek

Inductive and capacitive coupling has been used for surveillance in the past though. Several decades ago, I worked for a defense contractor and worked on classified stuff. Some of the buildings in our facility had no indoor plumbing. You literally had to go to another building if you wanted to pee. The reason for this is that electrical signals from computer monitors were found to be able to travel down water and drain pipes and could be picked up and deciphered. The building had its own generator and was as isolated as possible from the rest of the world electrically. It also had a high fence with barbed wire around the building.

Not to doubt you, but I find it hard to see how a building could meet fire codes without having some kind of plumbing system, and I can think of several ways to prevent pluming from acting as waveguides or conduits for coherent electrical signals. I have worked in facilities with wire-shielded rooms (essentially a faraday cage including an ‘airlock’ to ensure that there was always a continuous grounded shield) where highly secure processing was performed. The only facilities I’ve ever seen that don’t have some kind of a water-based fire suppression system (even as a secondary system or only for the administrative facilies) were warehouses and processing facilities for hydroreactive chemicals (primarily used in energetic electrochemical batteries or pyrotechnic/ordnance manufacture), which had very expensive perfluorooctanesulfonic fire suppression systems.

@engineer_comp_geek

People have been able to pick up sounds by shining a laser at windows to measure the window vibrations.

You can build an interferometer that can do this with an inexpensive presentation pointer grade laser for under a hundred dollars. The defense against it is equally simple, however; a white noise generator can make it all but impossible to extract the useful information from a signal, and a direct surface agitator can completely saturate the auditory signal, albeit at the price of having to listen to a persistent buzzing. A much easier solution is just to have a discussion in an interior room with no windows.

Unfortunately, no one has yet figured out a way to prevent the greatest vulnerability to security, to wit appeal to human ego and desire to compromise secrets from the inside. Essentially every major leak in US and UK intelligence history was due to human fallibility. (The greatest publically revealed US intercept of Soviet signals was Operation Ivy Bells, tapping an undersea cable in the Sea of Okhotsk, but there were numerous other examples of Soviet, most notably Arkady Shevchenko, Oleg Gordievesky, and of course Oleg Penkovsky, who firsted warned of and gave the location of IRBM launch sites in Cuba and also informed the US about the actual size of the operational Soviet nuclear arsenal.

Stranger