8 ms·

This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microph

by Akuehne 4mo ago

This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.

weard_beard 4mo ago
Sounds like you've got a great idea for a proof of concept for DefCon next year...
- DANmode 4mo ago
  Probably worth reviewing prior art for inspiration: 0) https://www.usenix.org/conference/usenixsecurity14/technical-sessions/presentation/michalevsky https://www.usenix.org/conference/usenixsecurity14/technical... 1) https://infocondb.org/con/black-hat/black-hat-europe-2014/gyrophone-eavesdropping-using-a-gyroscope https://infocondb.org/con/black-hat/black-hat-europe-2014/gy...
  - adm4 4mo ago
    Sounds salty. https://people.csail.mit.edu/mrub/papers/VisualMic_SIGGRAPH2014.pdf https://people.csail.mit.edu/mrub/papers/VisualMic_SIGGRAPH2... use a potato chip bag as a microphone
smallnix 4mo ago
I thought this has been done to capture keystrokes of a keyboard next to the phone already 2011 https://www.researchgate.net/publication/221609349_spiPhone_Decoding_vibrations_from_nearby_keyboards_using_mobile_phone_accelerometers https://www.researchgate.net/publication/221609349_spiPhone_...
pc86 4mo ago
It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.
- righthand 4mo ago
  The CIA…plug a set of regular headphones into a microphone jack, open a recording application and speak into the headphone speaker, you don’t need a 3 letter agency for that physics open secret.
  - tclancy 4mo ago
    I am crap with physics but was going to say I think the last 50+ years of speaker development has been about making them less a microphone than they inherently are.
    - righthand 4mo ago
      They transmit sound. Anything able to detect the vibrations make it a microphone. Not sure how a speaker gets around that because it’s job is to vibrate.
    - ssl-3 4mo ago
      No, not really. Dynamic loudspeakers and dynamic microphones are the same thing. They always have been the same. They've got the knobs for the design variables turned in different directions, but they're still the same. They even have the same frequency response whether they're being used as speakers or microphones at the moment. Which brings up a valid way to measure the response of a microphone's design: Use two of them. One as a speaker, and the other as a microphone. Play measurement-sounds out of one, and record the results on the other. Plot it out. The deviations are magnified, but eliminating that magnification is just a math problem -- not an instrumentation problem. :)
  - nerdsniper 4mo ago
    Wouldn't you need to rewire the headphones? Headphones use a 3-pin TRS whereas a 4-pin TRRS plug is used when you add a microphone. Regardless if the 4-pin is CTIA or OMTP, it's generally only going to get shorted to ground if a 3-pin TRS plug is plugged into a 4-pin TRRS socket, or if a 4-pin TRRS plug is plugged into a 3-pin TRS socket. Diagram: https://i.sstatic.net/8rSD2.jpg https://i.sstatic.net/8rSD2.jpg
jrflo 4mo ago
I don't think that's realistic. If you're looking at the acceleration sound waves cause against a phone's accelerometer, that's likely far below the sensitivity of the sensor- phones are too massive relative to the force of sound waves from speaking. F=ma, so the acceleration you're looking at is the force of the soundwave (tiny) divided by the phone's mass (relatively large). The only reason this kind of works is because you're putting the phone on an object that's mechanically vibrating. I suppose it would work in certain situations like putting the phone on top of a large speaker, but you'd never get the resolution to decipher audio from sound waves alone for a phone sitting on a desk or in a pocket
jjk166 4mo ago
I doubt the sampling rate is anywhere near what you would need to make out dialog in a sound recording. You might be able to tell who is speaking though if you had a voice profile.
nullc 4mo ago
This is why grapheneos creates 'sensors' as a permission. On android all apps can spy on you this way.

by Akuehne 4mo ago

weard_beard 4mo ago

Sounds like you've got a great idea for a proof of concept for DefCon next year...

DANmode 4mo ago
Probably worth reviewing prior art for inspiration: 0) https://www.usenix.org/conference/usenixsecurity14/technical-sessions/presentation/michalevsky https://www.usenix.org/conference/usenixsecurity14/technical... 1) https://infocondb.org/con/black-hat/black-hat-europe-2014/gyrophone-eavesdropping-using-a-gyroscope https://infocondb.org/con/black-hat/black-hat-europe-2014/gy...
- adm4 4mo ago
  Sounds salty. https://people.csail.mit.edu/mrub/papers/VisualMic_SIGGRAPH2014.pdf https://people.csail.mit.edu/mrub/papers/VisualMic_SIGGRAPH2... use a potato chip bag as a microphone

smallnix 4mo ago

I thought this has been done to capture keystrokes of a keyboard next to the phone already 2011 https://www.researchgate.net/publication/221609349_spiPhone_Decoding_vibrations_from_nearby_keyboards_using_mobile_phone_accelerometers https://www.researchgate.net/publication/221609349_spiPhone_...

pc86 4mo ago

It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.

righthand 4mo ago
The CIA…plug a set of regular headphones into a microphone jack, open a recording application and speak into the headphone speaker, you don’t need a 3 letter agency for that physics open secret.
- tclancy 4mo ago
  I am crap with physics but was going to say I think the last 50+ years of speaker development has been about making them less a microphone than they inherently are.
  - righthand 4mo ago
    They transmit sound. Anything able to detect the vibrations make it a microphone. Not sure how a speaker gets around that because it’s job is to vibrate.
  - ssl-3 4mo ago
    No, not really. Dynamic loudspeakers and dynamic microphones are the same thing. They always have been the same. They've got the knobs for the design variables turned in different directions, but they're still the same. They even have the same frequency response whether they're being used as speakers or microphones at the moment. Which brings up a valid way to measure the response of a microphone's design: Use two of them. One as a speaker, and the other as a microphone. Play measurement-sounds out of one, and record the results on the other. Plot it out. The deviations are magnified, but eliminating that magnification is just a math problem -- not an instrumentation problem. :)
- nerdsniper 4mo ago
  Wouldn't you need to rewire the headphones? Headphones use a 3-pin TRS whereas a 4-pin TRRS plug is used when you add a microphone. Regardless if the 4-pin is CTIA or OMTP, it's generally only going to get shorted to ground if a 3-pin TRS plug is plugged into a 4-pin TRRS socket, or if a 4-pin TRRS plug is plugged into a 3-pin TRS socket. Diagram: https://i.sstatic.net/8rSD2.jpg https://i.sstatic.net/8rSD2.jpg

jrflo 4mo ago

I don't think that's realistic. If you're looking at the acceleration sound waves cause against a phone's accelerometer, that's likely far below the sensitivity of the sensor- phones are too massive relative to the force of sound waves from speaking. F=ma, so the acceleration you're looking at is the force of the soundwave (tiny) divided by the phone's mass (relatively large). The only reason this kind of works is because you're putting the phone on an object that's mechanically vibrating. I suppose it would work in certain situations like putting the phone on top of a large speaker, but you'd never get the resolution to decipher audio from sound waves alone for a phone sitting on a desk or in a pocket

jjk166 4mo ago

I doubt the sampling rate is anywhere near what you would need to make out dialog in a sound recording. You might be able to tell who is speaking though if you had a voice profile.

nullc 4mo ago

This is why grapheneos creates 'sensors' as a permission. On android all apps can spy on you this way.