August 31, 2013

Potential Major Security Flaw on HP Laptop Discovered with RTL-SDR

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.

HP Laptop Microphone Leak at 24 MHz

August 9, 2013

Exploring Unintentional Radio Emissions with the RTL-SDR

Melissa Elliot (0xABAD1DEA), an infosec security researcher has uploaded slides on the topic of investigating unintentional radio emissions from various electronic devices, and the security issues these emissions can cause. She used the RTL-SDR as the radio receiver to show that sophisticated equipment isn’t needed. One interesting experiment she performed was trying to recover a checkerboard image displayed on an LCD screen entirely via its unintentional radio emissions received with the RTL-SDR. She got close, as you can sort of make out the checkerboard pattern on the recovered image below. Update: Tomsguide have written an article on Melissa’s talk.