Does a modern MacBook's green "camera light" always turn on when the camera is activated?

Question

Many people are seen to put strips of tape and other adhesive materials on their MacBook camera in an attempt to thwart any potential hacker from accessing their system and camera. MacBooks have a green "camera light" on the right side of the FaceTime camera on the front that seems to turn on when the camera is activated (i.e. the sensor is provided energy and transmits a signal to the motherboard).

Does the camera of a modern MacBook require that the green camera light turns on as well? In other words, is the camera light hardwired to the camera in such a way that if the camera is supplied electricity, that itself would enable the camera light? This would prevent a hacker from being able to obtain any information from the camera without the user being notified by the green light.

I've seen this question come up again and again, but no satisfactory/definitive answers were provided. The last time such a question was posted received an answer that linked to a research paper showing that it is possible to activate the camera without activating the camera light—but only on pre-2008 Macs. The answers to another question question come to a similar conclusion. A user did say that there was "[no] proof that you can do the same in post-2008 laptops," but this doesn't prove that the camera light is in fact hard-wired to the camera.

The fact that there is no proof for such an important security feature is rather strange. There must have been a group of designers and engineers who created the camera system—surely they would know and would have publicized this perhaps in an Apple support article or in an interview? Or perhaps this could have been discovered in a teardown by a group at iFixit (although I am no electrical engineer), but this doesn't seem to have happened yet. Most importantly, I would expect Apple to tout this as a security feature, but there is no mention of it on their site. Is there really 'no proof' as to whether the camera and camera light is hardwired or not?

Answer 1

There must have been a group of designers and engineers who created the camera and camera light system – they would surely know and have told others.

John Gruber received an email from one such former Apple engineer:

https://daringfireball.net/2019/02/on_covering_webcams

Security researchers at Johns Hopkins released a paper in 2013 revealing that the indicator lights on Macs released prior to 2008 could be circumvented by software. I linked to this in 2016, wondering if the same exploit was possible on more recent Macs. Here’s an answer I received from a former engineer at Apple who was intimately familiar with the software drivers for Mac webcams:

The original cameras had the problem that the JHU researchers detailed in the article that your linked to. Problem was that the firmware was downloaded on every boot and there was no security/encryption mechanism for verifying it. The part used was fairly common and the firmware was just in RAM (hence the loading after a cold boot), as oppose to flashed.

All cameras after that one were different: The hardware team tied the LED to a hardware signal from the sensor: If the (I believe) vertical sync was active, the LED would light up. There is NO firmware control to disable/enable the LED. The actual firmware is indeed flashable, but the part is not a generic part and there are mechanisms in place to verify the image being flashed. […]

So, no, I don’t believe that malware could be installed to enable the camera without lighting the LED. My concern would be a situation where a frame is captured so the LED is lit only for a very brief period of time.

The still photo problem — where the light only turns on for the instant the image is being captured — is interesting. But I would wager real money that the camera indicator light cannot be circumvented by software on any Mac released this decade.

^{emphasis mine}

Answer 2

Another source, this time directly from Apple, suggests that it is not possible to enable the camera without turning the indicator on. The quote (emphasis mine):

We design Apple products to protect your privacy and give you control over your information. Our products and features include innovative privacy technologies and techniques designed to minimize how much of your data we — or anyone else — can access. And powerful security features help prevent anyone except you from being able to access your information.

The FaceTime HD camera built into your Mac computer is designed with your privacy in mind and uses a camera indicator light that glows green when the camera is active. So you will always know when the camera is on.

The camera is engineered so that it can’t activate without the camera indicator light also turning on. This is how you can tell if your camera is on.

Source

Answer 3

An article on Forbes.com was talking about Apple warning against the use of camera covers. About halfway through the article, it mentions that the light "is wired in series with the camera".

On some laptops the indicator light can be hacked and turned off. However, as a reader has pointed out to me, Apple has a physical method to ensure the light can not be disabled. It is wired in series with the camera so if you turn off the light, power no longer goes to the camera.

But that doesn’t mean MacBook cameras are unhackable—there is no such thing. Why doesn’t Apple simply tell people to use a post it note to cover their camera—or even like some people I know, a piece of opaque tape?

Or better still, why doesn’t Apple build its own webcam cover into MacBooks? The firm is certainly not shy of bringing out new designs, especially ones that help improve privacy. It’s a small hardware change that could make a massive difference.

Answer 4

It is possible for the camera to be on while the green light is not. I just witnessed this on a 2019 MBP. It wasn't a burned out LED because the light did start working again. Restarts did not fix the problem. It seemed to fix itself, which is scarier in a way.

So, to answer the question, NO, the green light does not always turn on when the camera is on.