I posted this on my Discord, one of our members is a security guy and pointed out that anyone concerned about things like this would be using a device called a NLJD, Non-Linear Junction Detector: https://reiusa.net/nljd/, which can detect circuit boards:
> The NLJD antenna head is a transceiver (transmitter and receiver) that radiates a digital spread spectrum signal to determine the presence of electronic components. When the energy encounters semi-conductor junctions (diodes, transistors, circuit board connections, etc.), a harmonic signal returns to the receiver. The receiver measures the strength of the harmonic signal and distinguishes between 2nd or 3rd harmonics. When a stronger 2nd harmonic is represented on the display in red, it indicates an electronic junction has been detected. In this way, a hand-held ORION is used to sweep walls, objects, containers, furniture, and most types of surfaces to look for hidden electronics, regardless of whether the electronic device is turned on.
Exactly the kind of thing I was looking for! Although, I guess for a bug hidden within an electrical device (like that in the article), this approach wouldn't work?
I wonder how well these work against shielding? Might it be possible to build your own device like this?
On the keyboard and the USB controller on the host (right next to the port) however…
So unless they’re dumb enough to put it literally in the middle of the cable? My point stands. These tools don’t typically have the resolution to tell.
The article covers that under the section "detection".
TL;DR: You can easily detect it while it communicates via GSM, and the device is also shielded quite badly, resulting in lots of easily detectable RF interference while it works.
All you need is a cheap RF detector. Having access to a full spectrum analyzer or a SDR will make this even easier.
All this gets much harder while the thing lies dormant, waiting for noise activation or commands. So the "quick bug sweeps" you see in the movies are more difficult.
Good ones record long spans of audio, then transmit them in short infrequent bursts outside of working hours. You can leave GSM recording equipment overnight and analyze logs, but even when you see it in the logs it'll be hard to locate the device physically when it's not transmitting.
We used to have keychain lights that would start to blink whenever a nearby phone went off, I can imagine it could be set off by a device like this lol.
