I had an interesting thought while in a big division-wide meeting at work this week. We were going through a bunch of slides that were marked confidential — as one does in such meetings. The speaker was emphasizing the secrecy of the info.

As he was speaking into wireless mic.

The problem with the average wireless system is that it simply transmits an FM signal. Not a strong signal — the model that was being used was 10mw — but a signal that can reach quite a ways in case you’re a motivated receiver. Certainly it would reach into the next building over.

But what frequency are they transmitting at? How can you tell?

Well, for less than $300 you can get a broadband RF receiver like the Lime SDR. This’ll slurp down a 120MHz slice of the spectrum and you can easily analyze what’s on the air. It’s easy.

I brought this up to the AV tech and he looked a bit concerned about it.

No one had thought of it.

It’s not a threat vector that you normally think of. But that’s exactly how you’ll start leaking secrets.

(Note: I’m being public with this since it’s a trivial attack vector that’s simply commonly overlooked.)