I know this is all in good fun, but you all are uncomfortably close to describing things that will soon get added to the practical threat landscape.
As long as you have a flexible hardware platform that lets you crank up some of the voltage regulator outputs, gpios that can be attached to a long trace/external wire as a makeshift antenna and have a decently fast cpu clock you have all the ingredients for a crude but usable software defined radio. maybe not super fast if you can't repurpose a hardware phy or radio interface, but more than enough bandwidth to exfil a secret key or 10 for maybe a couple dozen meters.
Tools to do sdr utilizing only general purpose processors and no radio specific gear are already available here and there as research implementations, and code that uses gpus/audio dacs/ and re-purposed phys to make a radio interface with a different spec or broadcast frequency is already in production use (wifi phy using a dvb radio interface -> tv whitespace communicator).
Using an approach like that to exfil or bridge an air gap is just too tempting for it to not happen. Honestly, I'd be willing to bet there's already an example of that somewhere out there in the wild today.
Paranoid thinking is an extremely valuable asset for security researchers. The things we're all joking about are impractical for an average person, but in a spy vs. spy scenario, especially when each side is well funded, these are the kind of things that will actually get used.
Examples of genuine vulnerabilities that would make you look paranoid just by defending against:
* Make educated guesses about passwords from a microphone recording of the keypresses. Both the intervals between keypresses indicate the region of the keyboard being touched, and the sound of each key differs slightly. Given a statistically significant sample of typing, you could deduce which keys are which based on the frequency of their use. http://www.securityfocus.com/news/11318
As long as you have a flexible hardware platform that lets you crank up some of the voltage regulator outputs, gpios that can be attached to a long trace/external wire as a makeshift antenna and have a decently fast cpu clock you have all the ingredients for a crude but usable software defined radio. maybe not super fast if you can't repurpose a hardware phy or radio interface, but more than enough bandwidth to exfil a secret key or 10 for maybe a couple dozen meters.
Tools to do sdr utilizing only general purpose processors and no radio specific gear are already available here and there as research implementations, and code that uses gpus/audio dacs/ and re-purposed phys to make a radio interface with a different spec or broadcast frequency is already in production use (wifi phy using a dvb radio interface -> tv whitespace communicator).
Using an approach like that to exfil or bridge an air gap is just too tempting for it to not happen. Honestly, I'd be willing to bet there's already an example of that somewhere out there in the wild today.