sidebands of great justice [was: Meet “badBIOS,” the mysterious Mac and PC malware that jumps airgaps]

[Andy Isaacson]

On Thu, Nov 07, 2013 at 05:26:24PM -0800, coderman wrote:
> friend and i spent a few hours earlier this week playing around with
> high frequency data transmission over PC speakers and microphones.
> 
> my hearing is rather poor, as sounds > 13kHz are inaudible to me.
> $friend can hear just over 17kHz.
> 
> a few normal laptops and mics were able to emit and receive in the
> 18kHz to 20kHz frequencies just fine, and (unsurprisingly enough)
> there's almost nothing in this range naturally.
> 
> a side channel just waiting for use!
> 
> bit rate is poor in our limited example, however.  i'll leave high
> speed, error correcting implementations to the reader ;)

Or, you know, just look on github.

https://github.com/piannucci/blurt

-andy