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Headphones can be hijacked to surreptitiously record audio

wired.com

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Re: Headphones can be hijacked to surreptitiously record audio

#91

Post by enraged_camel »

bcheung wrote: post #83

Here's a neat party trick for you. I had a MacGyver moment in the past where I made a phone call with only are pair of old earbuds and a phone cord (no switches, no dial pad). A speaker is basically the same thing as a microphone in reverse. Normally it takes an electrical signal to move a physical element that creates the sound waves. But you can also move the element and it will generate an electrical signal. To di…

I don't know what kinds of parties you attend, man...

But that sounds like a fun trick!

Re: Headphones can be hijacked to surreptitiously record audio

#92

Post by mark-r »

a3n wrote: post #89
mark-r wrote: post #10

Earlier quoted context omitted.

Most people don't play sounds all day. But this does point to a viable defense, if the headphones are always playing something they can't be used to record.

Why couldn't you switch between input and output fast enough that you can't hear the difference, prioritizing output, and get low fidelity but viable input?

Producing output requires vibrating the headphone elements. That vibration will completely swamp any vibration induced by the sound in the room. Cutting the output long enough to dampen those vibrations will certainly be noticeable.

Re: Headphones can be hijacked to surreptitiously record audio

#93

Post by ChuckMcM »

IshKebab wrote: post #57

The bit you want to know: > Their malware uses a little-known feature of RealTek audio codec chips to silently “retask” the computer’s output channel as an input channel

Not a "little known" feature, it is the feature that lets you plug your head phones into any of the 6 jacks that it looks like it fits in on the back of your computer and the little pop up says "Are those headphones you just plugged in?" you say yes and that jack is retasked as as headphone jack even though it was the subwoofer output according to the legend on the computer plate.

Its a "feature" that they have sold to a lot of manufacturers as an ease of use thing for people who are frustrated because they plugged in their headphones but get no sound.

Re: Headphones can be hijacked to surreptitiously record audio

#94

Post by anigbrowl »

bcheung wrote: post #83

Here's a neat party trick for you. I had a MacGyver moment in the past where I made a phone call with only are pair of old earbuds and a phone cord (no switches, no dial pad). A speaker is basically the same thing as a microphone in reverse. Normally it takes an electrical signal to move a physical element that creates the sound waves. But you can also move the element and it will generate an electrical signal. To di…

You don't even need to disconnect the ear bud, just tap it. The voltage pulse from an audio signal is sufficient. Back in the days of rotary phones I used to show off how to dial numbers by simply tapping the receiver on the table.

Re: Headphones can be hijacked to surreptitiously record audio

#95

Post by anigbrowl »

mojuba wrote: post #73
Senji wrote: post #59

Earlier quoted context omitted.

It's a selling point. You plug anything at the back then change the jack's purpose in the control panel gui for the audio card.

Possibly, but why isn't the feature exposed to end users then?

As a sound engineer, I can assure you that this feature has been around for ages.

Re: Headphones can be hijacked to surreptitiously record audio

#96

Post by jkaptur »

CogMonster wrote: post #68
posterboy wrote: post #63

makes me wonder if the same thing goes for screens, because the reverse photoelectric effect in LEDs can be reversed.

You would still need a lens to form an image on the screen.

It might be possible to use multiple screens to form a sort-of synthetic lens. Also, there is such a thing as a single-pixel camera (http://dsp.rice.edu/cscamera).

Re: Headphones can be hijacked to surreptitiously record audio

#97

Post by anigbrowl »

egh5oon wrote: post #40
orblivion wrote: post #12

Would be cool if Purism or similar companies had a nice big hardware switch that controlled access to any recording equipment.

A camera/mic switch should be required by law on every laptop and phone. Please don tell me a 5c switch is too expensive for a $300 phone.

And if the switch is too prominent people will whine about accidentally switching things off when they didn't mean to. So the switch would get moved out of the way, and pretty soon people would just turn it off (if it's even on by default, which it probably won't be) and leave it off, because most people can't imagine why anyone would bother to exploit such capabilities.

Re: Headphones can be hijacked to surreptitiously record audio

#98

Post by mojuba »

anigbrowl wrote: post #95
mojuba wrote: post #73

Earlier quoted context omitted.

Possibly, but why isn't the feature exposed to end users then?

As a sound engineer, I can assure you that this feature has been around for ages.

Well then what the article describes is not even a "hack"...

Re: Headphones can be hijacked to surreptitiously record audio

#99

Post by illumin8 »

bcheung wrote: post #83

Here's a neat party trick for you. I had a MacGyver moment in the past where I made a phone call with only are pair of old earbuds and a phone cord (no switches, no dial pad). A speaker is basically the same thing as a microphone in reverse. Normally it takes an electrical signal to move a physical element that creates the sound waves. But you can also move the element and it will generate an electrical signal. To di…

As a DJ, I learned the trick to plugging your headphones into the Mic jack and yelling very loudly into the cans as a cheap microphone. It works in a pinch; not the best sound quality though.
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