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I would like to learn how to search a laptop/computer/cell for processes scanning the mic input. Additionally, short of physically disabeling the mic input, is there a way to make sure nobody is tapping the input signal?

Edit: I do trust neither the OS (Windows) nor the driver.

Edit 2: It is not an option to disconnect the device (permanently) from the internet.

Current status:

  • For windows there is no better way than physically disabeling the microphone or to disconnect completely from the internet.
  • For Linux/Android there is the possiblility to check the sources.
  • One could try to inspect all outgoing packages for audio content.

Since there is some discussion on wether or not the driver vendors and big os companies are trustworthy, here some additional information:

  • NarusInsight is a "network traffic intelligence system that supports real-time precision targeting, capturing and reconstruction of webmail traffic" NarusInsight.
  • Magic Lantern is keystroke logging software developed by the United States' Federal Bureau of Investigation Magic Lantern.
  • It seems NSA access was built into Windows NSAKEY.
  • Microsemi put a backdoor insida a US military chip Microsemi

I would be very interested on how to make sure my laptops microphone is not used for surveillance.

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If you're on Linux, then you might be interested in reading answers to the Can I query which processes (if any) are currently accessing the microphone? question. On Windows, you could either disable the microphone in your drivers (if supported, there's many of different ones), or set the recording volume to its lowest point, mute mic or "Mute all" in the Recording Control dialog. Some computers will also have ability to disable microphone in BIOS, but it will greatly depend on your hardware and operating system used how to do that. –  TildalWave Jul 6 '13 at 18:31
Of course, the easiest is to simply disconnect your devices from accessing Internet. Pop the battery out of your phone, disconnect your computer / notebook from any wireless access points, or pull the network cable out. Even better - don't even take your devices with you to wherever confidential information will be exchanged verbally. –  TildalWave Jul 6 '13 at 18:38
What if a virus turn the buzzer into mic (technically a buzzer is a near a mic)? –  F. Hauri Jul 9 '13 at 16:56
@F.Hauri Turning the buzzer into a microphone seems way more sophisticated than simply using the drivers API. –  user27997 Jul 9 '13 at 18:21
On Windows, you ought to be able to find a terrible broken driver that will foil any attempts to get the mic working. Ever since Realtek got big it seems that everyone has forgotten how to write basic drivers :P –  Matthew Read Sep 15 at 20:16

4 Answers 4

up vote 1 down vote accepted

You can't. If they want to spy on you they will and it will be difficult for you to find out end of story.

  • If you don't want them to hear you through the PC mic drill a hole through it.
  • If you don't want them seeing you on the built in web cam cover it up or drill a hole through it.
  • Don't use windows rather build your own flavor of linux from scratch.
  • They will still find a way to spy on you if they really want to these are very smart people and their job is to spy.
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Yes, this seems to be the concensus. I am less concerned about targeted spying (I am not very interesting), but rather about mass surveillance. This could be done for example by scanning the microphone input on all windows computers and sending a ping when some classification criterion is met. I wonder how I would detect such a thing. Watching outgoing packets will not work as long as the classifier is not hit. –  user27997 Jul 12 '13 at 18:10
The only thing that can really be done is to understand how the monitoring is done so you can avoid incriminating yourself. Almost every modern device has a camera and microphone. All of my new laptops have cameras, my phone has 2 cameras, all of those devices have microphones and all of them are connected to the internet and therefore all are potential spy tools for badguys or government. You could watch outgoing packets but they're probably going to be encrypted and not going directly to the source. –  Four_0h_Three Sep 18 '13 at 13:53
It's sad that we have to have this mindset but just like in the book 1984 we all now have cameras and microphones in our houses, at our workplaces, where we shop, in public areas and in our cars. We're under constant surveillance and the only thing that can stop that is a massive public outcry. We have seen some outcry but it's not been enough yet. –  Four_0h_Three Sep 18 '13 at 13:57

In order to combat a roving bug you can install a switch to disable your microphone.

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It depends on what level you trust your device. If you trust the drivers, you could simply mute it in the driver and as long as the kernel and driver are secure, it shouldn't be possible for an application to read the input from the mic unless it has kernel level access. If you don't trust the security of the kernel or driver, then all bets are off unless you physically disable the mic.

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No, I do not trust the drivers or the OS. I would trust a generic open source driver, but such a thing does not seem to exist. –  user27997 Jul 8 '13 at 11:02
@user13247 - Why don't you trust the operating system? In the case of a desktop just disconnect the mic, in the case of a laptop, disable the device in Device Manager. –  Ramhound Jul 9 '13 at 15:23
@Ramhound: Device Manager means Windows, i.e. Microsoft. Its trustworthiness is well-known (and zero). –  MSalters Jul 10 '13 at 14:38
@MSalters - Where exactly has it been proven that Microsoft's trustworthiness is zero? I mean if it was proven to be zero why would governments use Microsoft's products? There are a ton of rumors that have never really been proven by anyone with actual knowlege on the subject. –  Ramhound Jul 10 '13 at 15:59
@user13247 - You can inspect the incoming and outgoing packets for one. –  Ramhound Jul 11 '13 at 10:50

You can disable sound output in your operating system and then block it but the operating system you use is only one aspect of a computer's functionality. This will be ineffective if somebody with good resources wants to spy on you.

You can also disable the microphone in the BIOS but that would be a software switch, there are work arounds to this and the BIOS can be hacked without you knowing.

Simply disconnecting from the internet is not enough, you will have to connect again eventually and the microphone can be recording audio to send somewhere as the computer is running. In later computers using Intel CPUs there has also been some 3G chips found which can be used to wake the computer remotely or mess with the BIOS without you knowing about it.

The only way to ensure that the microphone is fully disabled is to fully remove it or if you know somebody with the skill to do so withoit damaging the motherboard (if it is integrated) ask him to drill a hole through it. On some laptops plugging something into the hifi microphone port can be done to disable the microphone but that depends on the individual laptop model.

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