A few weeks back we posted about some slides from the Defcon conference by information security researcher Melissa Elliot which detailed how she used an RTL-SDR to explore the world of unintended radio emissions.
The talk to go with the slides is now available on YouTube
Over on Reddit, user cronek discovered by using his RTL-SDR that the microphone on his HP EliteBook 8460p laptop computer was continuously and unintentionally transmitting the audio from the built in microphone at 24 MHz in FM modulation. He found that the only requirement needed for the microphone to transmit was that the laptop needed to be turned on – even muting the microphone did nothing to stop the transmission.
Click here to read the original post.
I accidentally stumbled upon a signal in the 24MHz range, appearing to be 4 carriers. I tuned to it and heard silence, then someone came into my office and started talking and I could hear them speak. The signal appeared to be coming from my other laptop (not the one running the SDR) and was pretty weak (my antenna, the crappy one that comes with the dongle, stuck to a metal stapler was right next to the HP laptop).
This is of potential concern as as the US Military is apparently transitioning to this particular laptop. However, this may be an isolated incident, as in the thread cronek explains that other laptops he tested did not display this behavior.
