They may be wired to the power line. I think the goal is more to give the kernel some way to know the mic/camera is explicitly disabled and not disconnected/missing/broken.

Wouldn't that tell any spy device / software that the subject has switched off the means he or she can be surveiled by? I cannot see how this could help with anything. They should rather do a physical switch that would 0 the data lines from these devices, so that camera or the microphone would be seen as working, but not sending any signal. Even better if you could pre-program some kind of ambience sound and pre-recorded cam video, so that once you turn it off, the perpetrator will think that they are still getting something.

Why would you care about fooling surveillance? The goal is to prevent a potential adversary from getting any video/audio footage, them being aware of you actively blocking any attempts is not really relevant.

Besides, the vast majority of users will not be under active attack. Having an on-screen popup when you try to use the webcam telling you that it has been hardware-disabled is quite a must-have. If you don't have something like this, you'll get a lot of support calls which boil down to "you accidentally pressed the kill switch, press it again to re-enable".

> Why would you care about fooling surveillance?

For example, when you are "required" [1] to run surveillance software on your computer.

[1] https://www.vice.com/en/article/n7wxvd/students-are-rebellin...

...then you just cover the camera and/or mic with a physical cover, such a piece of tape.

> and/or mic

How well would tape work on that?

These exam proctoring softwares are only required to be run during the time you are actively taking an exam. The rest of the time, there would be zero issue for a student with hardware disabled camera and microphone.

The invasive proprietary software used to prevent cheating cannot be trusted to work only when the students want it work. Its purpose can and will be twisted to fit the agendas of whoever owns the software. It probably introduces several security vulnerabilities into the system just by being installed.

It's a Chrome extension.

> If you don't have something like this, you'll get a lot of support calls which boil down to "you accidentally pressed the kill switch, press it again to re-enable".

Yep. This was an extremely common issue in the mid-2000s, when laptops started integrating wireless hardware with hard power switches, often on the side of the laptop where they could easily be toggled by accident.

But was it a "fault" of the switch itself or lack of meaningful feedback that the switch was engaged? It seems like they have not implemented it properly and then say it wasn't a good idea, without really giving it a chance.

It might be for usability reasons: having your video conferencing application tell you "Your webcam appears to be disabled by the privacy switch, is that intentional?" probably saves a lot of time in tech support calls.

Also, having your video conferencing application send some prerecorded audio and video data to your colleagues because you inadvertently turned the kill switch would not be a highly desirable outcome.

Unless you record infinite video and sound it's pretty easy to check if the video is a loop. Even static video of an empty room would have variations over time while a recording would be identical. Even auto-generated audio and noise would have a pattern which can be matched on. And if an attacker has control over your machine they can trivially correlate it with other activity to detect fake input.

It's basically a false sense of security which is generally worse than doing nothing.

If you can pattern match all auto generated audio you can prove there’s no one way functions and that cryptographic hash functions don’t exist.

Detecting the pattern in a prng stream is equivalent to finding its Kolmogorov complexity. https://en.m.wikipedia.org/wiki/Kolmogorov_complexity#Chaiti...

You're not pattern matching all auto-generated audio. You are pattern matching the audio generated by a specific algorithm. An attacker who has access to your microphone will know which laptop you have and what hardware it has.

This assumes an attacker is targeting you specifically since otherwise this is all moot (a broad attack could care less as to why your microphone is off).

You wouldn't be using a PRNG for this, because what would be the point? The idea would be to generate some plausible-sounding audio, not garbage that a listener would obviously know isn't real.

Really, though, in general there's just no point to this altogether; just cutting power/data to the mic is fine. There's no need to attempt to fool someone with fake audio, outside of some very edge-case scenarios that I'm sure Dell (rightly) does not care about.

>Wouldn't that tell any spy device / software that the subject has switched off the means he or she can be surveiled by?

And the spy device/software knowing the user has "switched off the means" vs "they are broken" is important because?

>They should rather do a physical switch that would 0 the data lines from these devices,

What exactly do you expect that to accomplish. Anyone actively targeting you getting literally NO SOUND OR VIDEO is going to know that you've flipped the switch just the same.

Even the quietest apartment has HVAC that will be picked up. If they're recording for hours they're going to hear people walking by. The camera itself will still provide an image, even if it's black, that looks different than no signal at all.

That's why the idea of having some pre-recorded stuff on tap, but sending no signal could waste some of the perpetrators resources, which I think is something nicer to have than letting them know it is switched off.

Sorry but if you're going to those lengths you should be buying a laptop without a camera or mic. Do video calls from your phone and put it in a soundproof/wireless transmission proof box.

If a nation state is able to get to your laptop they're going to figure out pretty quickly that you're "feeding something pre-recorded" into the mic and camera every time you have a meeting. Ignoring the insane effort you'd have to put out to feed that in and make it even semi-believable. For starters they are presumably tracking who you're meeting with - are you going to have a meeting before your meeting to pre-record? Hope they don't figure out that you're saying the exact same thing in two different meetings? Somehow have root on your laptop but aren't bright enough to figure out you're feeding data from a local file into your mic and camera?

Thank you! Great answer

I believe the switches are there for the user as a simple way of activating or deactivating the microphone and camera and for them to know (via LEDs) the current state.

If you have a spy device connected to your computer or have malware running, you are very screwed in a million different ways already. Limiting knowledge of hardware state to malware doesn't buy you much.

If it is switched off, then you cannot be surveiled by it. Mission accomplished.

I belive you can blacklist that driver if needed.

> Why not just wire the LEDs up to the same power line that goes to the camera?

It's just difficult enough to not bother considering the market doesn't care.

Webcams are typically USB 2.0 devices using generic drivers from the operating system or manufacturer. It's easy from a hardware and software perspective to send a command to the webcam to disable itself and turn off its LED. If you want to completely cut power then you need to add power switching circuitry.

You could use one of your CPU's limited GPIO pins to control the switching but now you probably need a smart power switch (~$0.30, which is significant) since the low voltage (1.2V?) GPIO can't handle switching a regular mosfet gate. GPIO writes are usually easy (just write to a memory address), but you'd still need to modify the vendor driver to do this and then distribute the driver.

Motherboards typically have embedded controllers which have GPIO - on desktops there is a SuperIO chip, I believe laptops typically use a regular microcontroller. Now you have some 3.3V GPIOs that can handle gate switching so you can use a regular MOSFET (~$0.10). You still need to modify and distribute the webcam driver, and now it might have to communicate with another driver which is handling the embedded controller.

Now you have to deal with the webcam disconnecting and reconnecting as you switch power to it. You want the device to always be present even if it's not enumerating on the USB bus, so you can select the webcam in zoom and turn it on and so you're not constantly playing the hardware connect/disconnect sound - even more driver changes. Maybe the webcam takes significantly longer to turn on now because it has to boot and enumerate.

That was all somewhat informed speculation, but I think it illustrates how a seemingly simple thing gets complicated. The electronics industry could easily solve these issues if there was motivation, but there just isn't.

Edit: Well, I'm posting this on an article talking about a vendor which is doing the work to make this happen. I guess I should say there's just enough motivation to eventually get around to solving this problem in a mature market.

False.

The market does care.

People want: hardware kill switches.

They want to cut their camera. (I've seen tape many times)

They want to mute their microphone for real.

Even non-nefarious "on-screen" mute buttons are subject to abuse.

For instance, in webex the conference host can unmute one or all of other people's mute buttons remotely. (To be clear there is a use case for this)

I wonder how many apps are listening even while mute is on. I would expect many of them.

and then there are exploits, which are lower probability but can do much more damage.

Or you can just bake the functionality into the webcam itself (like apple) and a cheap commodity item becomes complicated and expensive.

You'll need a special firmware for the cam (like apple device), need to ensure integrity of the said firmware and also need a customized driver which needs maintenance work.

I have an old Logitech Pro 9000 camera with a lot of bells and whistles but, when I found out that its light can be managed by the driver and the UVC client in Linux AND it can turned off while it's recording, I've never kept it connected longer than it should be.

So yes, custom and secure hardware is hard.

Connect the LED via current mirror to webcam power line? You will know when webcam is recording because it draws far more power.

That seems to be an issue with most webcams - the indicator light itself can be compromised and disabled.

I remember having a usb Logitech webcam that included disabling the indicator as a first class option in their control panel - not a big leap to imagine malware doing it

Third party webcams, yes.

Basically any modern laptop with a build-in webcam has a hardware controlled LED, not software controlled.

I don't see that this is necessarily true or easy to figure out.

I remember a hack were basically if you just light up the camera, take a pic, and power off it, the led don't have enough time to emit light.

Even if the LED remained on, the victim would be powerless to do anything about the picture that was taken. I've seen videos on youtube of scammers doing this to blackmail their victims.

Kill switches should be mechanical and should physically disconnect the device from the system. Kill switches and lights that are controllable by software will be exploited.

I know, was just showing that LED wired on power is not enough.

Perhaps because all it takes is 1/24th of a second to make a picture?

Or because once the light is on, it's too late?

Or because I don't want to risk missing the light being on, just because the computer is on but I m not behind it?

It would be super nice for manufacturers to start doing that, but this is not a silver bullet. There's been so many times where I've just had my laptop stay open and on for different reasons. If in such scenarios the webcam comes on, the likelihood of me seeing the camera light on is quite low. I'm sure I'm not the only person either. Hardware switch is still the best solution.

My lenovo laptop has basically a builtin webcam cover, and I absolutely love it.

...Another LED for the data wire then?

What would that achieve exactly?

This one wouldn't be always on, but blink on signal. Way to differentiate between activity and just being plugged in.

A “kill switch” is more preferable because it prevents an attack, whereas wiring the LED to the power line only notifies you when you’ve been attacked; by then it’s too late; you’ve already been compromised.

So the NSA/CIA/FBI can enable the camera/mic without you knowing.

Lovely; care to enlighten the rest of us?

It’s a rhetorical question. There’s no good reason not to do it.

The main reason is cost and hardware complexity, which would be negligible if the camera asic simply had an “I am on” pin to drive an LED. Laptop manufacturers clearly don’t care about this issue enough to insist that camera and audio hardware manufacturers include such a pin on future models.