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

[coderman]

On Sun, Nov 3, 2013 at 12:47 AM, grarpamp <grarpamp at gmail.com> wrote:
> ...
> Unlikely the average laptop would adequately cover
> the airgap in this frequency range. Signal to noise
> ratio and packet loss are further inhibitive to data
> transmission.

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 ;)


best regards,