[tr1ck5t3r]

I dont know about ultrasonic, but I certainly have a camcorder recording of some high frequency sounds which could be used to jump air gaps much like dial up modems used to make when handshaking. You wouldnt hear the sound in a normal office environment only in a silent office, because the external speakers & amp were turned up close to max but not playing anything which is also not normal for most offices. Its quite likely whilst highly technical those behind this form of attack are not able to deduce what environment the attack is taking place in like a normal office or a silent office.

As speakers can be used as microphones (technology is essentially the same just different ohms and materials used for the cone) and modern motherboards can detect when a 3.5mm jack plug is plugged into a headphone socket, it might be possible to have the speakers acting as a microphone in some situations. Its something I'm still looking into, but I have noticed the some DJ mixes on Youtube will play up ie going quiet when you have headphone's plugged in but not when using built in speakers like those found on a laptop. You can reset the mix going quiet by unplugging the 3.5mm stereo jack, now whether this is some sort of DRM technology being used as some of the DJ mixes will be illegal copies uploaded to Youtube, I dont know yet just like I dont know if these are related or separate events to BadBios. Its not unheard of big corps to employ methods to disrupt illegal copies of music & films, the Sony rootkit on some of their music CD's is one such example of big corporations hacking their customers. https://en.wikipedia.org/wiki/Sony_BMG_copy_protection_rootk...

[geofft]

Yes, you could use it to jump air gaps. (In fact, that technology is already deployed in production in Chromecast pairing, when your phone is not on the same network as your Chromecast.)

But don't you need something on the other side to receive and decode the data being sent? What's the BadBIOS story for how the infection initially happened?

(Is the assertion that something along the lines of Intel ME is already listening for control instructions over ultrasound?)

[zdkl]

The CIA has been known to tamper with electronics, so between that and pre-backdoored hardware (IME) it's fairly likely that a determined opponent has one or more means to passively wait for a payload in a hard to detect manner.

From there, it's turtles all the way down; you "only" need to deliver an ulterior, possibly tailored, payload from any of the several methods described in this thread.

[nitrogen]

Could those high pitched sounds you recorded just be capacitor whine or noise on the power supply? All cheap sound interfaces in computers produce noise that correlates with CPU, GPU, or bus activity, and many power supplies make squealing sounds that can be heard in quiet rooms. It's conceivable these could be manipulated as side channels in an already compromised system, but they exist regardless of compromise.

[zdkl]

That's the beauty of such methods. Anytime an avenue for compromise seems "noisy", I'd be willing to bet someone smart organised and well funded has investigated using it for hi-value penetration.