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How do headphones work? Do they contain any firmware or any instruction set? Are they vulnerable to anything? Good old wired analog Jack ones, not USB wired, wireless, Bluetooth which have lot of fundamental flaws in design...

  • Cheap headphones won't have any firmware, high end head phones might have some for EQ, active noise cancelling headphones will. Not sure you could do much of interest though. Change someone's bass settings maybe. – iainpb Mar 11 '18 at 13:15
  • @iainpb I'd actually be surprised if noise-cancelling headphones had firmware. I imagine the circuitry is entirely implemented in hardware (after all, all it needs to do is echo a 90° copy of the sound). – forest Mar 12 '18 at 2:48
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    See also security.stackexchange.com/q/127111/165253 – forest Mar 12 '18 at 8:10
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Analog audio cables do not carry any digital information. While some higher-end audio products may have firmware for equalization, sophisticated noise cancelling, or filtering, the firmware cannot be updated over the audio jack. The connections are entirely analog. They usually connect directly to each speaker's voice coil, although they sometimes pass through powered amplifiers first in the case that the driver has a resistance too high to power directly. See also Phone connector.

Do they contain any firmware

Some high-end devices do have firmware for post-processing of the analog audio. This firmware is either not meant to be updated, or can only be updated over a dedicated digital interface. The analog audio cable would not be used for updates unless the manufacturer is silly updates the firmware by encoding digital information in a frequency range supported by the computer's DAC.

or any instruction set

An instruction set is specific to CPUs (whether it's a simple 4-bit MCU or a modern, sophisticated x86 CPU). An IC that has firmware may or may not have an instruction set. This is generally irrelevant to the capabilities of an IC and its security implications, as you can still have a turing-complete circuit with no real instruction set.

  • what about 'speaker driver' are they hardware/software interacting installing / device detector 'drivers'? – Aoi. T_015 Mar 12 '18 at 8:37
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    @Aoi.T_015 This is a speaker driver. A speaker driver is a transducer coil around a magnet connected to a diaphragm. It's the part of the speaker that creates the actual noise. A speaker driver is classified as either a woofer, a tweeter, or a midrange. This gives a more full explanation. They are not software. – forest Mar 12 '18 at 8:44
  • I see, so doesn't have any 'codes' but what about chip, does it have any chip that can be modified/ exploited? BTW are analog headphones plug n' play cause realtek audio manager & windows audio detects headphone when inserted, lets switch between the two – Aoi. T_015 Mar 12 '18 at 8:56
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    @Aoi.T_015 Some may have a chip for the reasons I mentioned (equalizers, etc), but they cannot be updated over the audio cable. And they are not part of the Plug N' Play specification, but the computer can detect when the jack is inserted. Unlike PNP where the device actually communicates with the computer, this is an entirely analog process (i.e. it's detecting the fact that something is letting electricity through). – forest Mar 12 '18 at 9:00
  • Could this headphone amazon.in/gp/product/B005643FD4 have firmware? – Aoi. T_015 Mar 30 '18 at 10:46
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"How do headphones work" is not a security question, and could be answered by doing some online research.

"Good old wired jack" headphones are entirely analog. Have you ever taken apart some cheap earbuds before? You'll see the wires connect directly to an electromagnet in each speaker.

Any vulnerabilities would be limited to physical security; e.g. tapping the cable to record what you are hearing, or cutting the cable to cause a denial of service.

If the headphones use batteries, it is not infeasible that they contain firmware but it is unlikely in most cases. It would be difficult to know what vulnerabilities could exist without specific examples of such implementations.

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See this site: https://www.cnet.com/products/apple-airpods/review/

Apparently Apple's Airpods have received a software update. Which implies there is a processor, an operating system, software running on the operating system, and firmware that can be updated.

I suppose they are not the only ones, and I would expect a trend where sound quality is improved not by using better sound hardware, but more sophisticated software.

As far as vulnerabilities are concerned, these Airpods are most likely only supposed to ever receive firmware updates from Apple, so that can be made safe. And if there is a vulnerability, what could it do? Shout in your ears? There's no microphone, no ability to send any data anywhere.

  • What can it do? Record what it hears (including sensitive information) and transmit it to an adversary either wirelessly or through whatever vector it uses to get firmware updates. – forest Mar 12 '18 at 2:49
  • uh, spread to other devices like BADUSB? – Aoi. T_015 Mar 12 '18 at 6:10
  • what about not 'modern', but traditional cheap avg analog jack ones – Aoi. T_015 Mar 12 '18 at 6:16

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