
Hardware Microphone Disconnect in Mac and iPad - gtufano
https://support.apple.com/guide/security/secbbd20b00b/1/web/1
======
est31
It's weird how the "hardware disconnect" term for the pre-2019 devices was
stretched to include a firmware, that is software-only, feature. Kinda like
the "end to end encryption" of Zoom. Glad that Apple resolved this for newer
devices. I'd still love to see wiring diagrams or explanations how it actually
works. Which kind of circuit do they use? Is it the power line that's
suppressed or the data line? Is it only an analog line that's suppressed and
if you tune up internal amp you might be getting some residual?

About the iPads, what does their "hardware" based microphone disconnect
entail? It has to be some electro-magnetic based communication instead of
currents so the circuit has to be more complicated. I doubt it's done without
using any kind of software but would be glad to hear otherwise.

Overall, I'm glad that they are responding to concerns and working to address
them.

~~~
jwr
> I'd still love to see wiring diagrams or explanations how it actually works.
> Which kind of circuit do they use?

I'd like to see that too, but I don't think we will. I suspect it's a magnetic
switch and I'm also curious which lines it cuts.

FWIW, you can still get some audio from an accelerometer if you can get it to
report data with a high enough frequency.

Not sure what you mean about iPhones, their information does not mention the
iPhone (and I would not expect it to).

~~~
derefr
I’d think the raw pressure-level input from the force sensors on the trackpad
would be even more accurate. It’s essentially an array of transducers already.

~~~
markrages
An accelerometer on a physical object is a force sensor. F=mA

------
geekifier
Despite Apple's anti-competitive ways, I am often impressed with their
attention to details such as these. Glad there is still sanity out there in
the world of "always listening" devices.

~~~
thebruce87m
I wish people would qualify their “Apple Hate” every time they mention it. It
would make it easier to know who’s opinions to discount.

An alarming number of people still believe Apple slowed down all their old
phones for the sole purpose of selling them new ones for example.

~~~
bakedbeanz
They did absolutely slow down their older phones, but it comes down to whether
you believe that their explanation of why was the whole truth.
[https://techcrunch.com/2020/03/02/apple-agrees-to-
settlement...](https://techcrunch.com/2020/03/02/apple-agrees-to-settlement-
of-up-to-500-million-from-lawsuit-alleging-it-throttled-older-phones/)

I'm not an Apple hater or a fanboy. I've owned a number of Apple devices in
the past. However, they have their issues just like any other tech company,
but their devoted following does seem to be more cultish than that of, say,
Microsoft or Google.

~~~
thebruce87m
I know the intricacies of what they did. To summarise: some phones with older
batteries would suffer brownouts because the internal resistance of the
battery was too high. They updated the OS to detect the brownout and throttle
the CPU to prevent it happening again.

So they didn’t slow down all old phones, only ones that had the problem. They
actually attempted to fix older models. To me this is the opposite of planned
obsolescence and appeals to my environmental view that all manufacturers
should be supporting their hardware as least as long as Apple currently does.

Now they didn’t communicate, and were fined. I think that is fair enough, but
I feel the size of the fine was quite excessive given they were trying to
extend the life of their customers hardware.

Note that the other phone manufacturers that have exactly the same problems
did nothing and are actually better off because of it.

~~~
mthoms
Your "summary" curiously omits one of the most important details — That the
battery could be replaced and the phone would perform _like new_. If not, the
ever deteriorating battery would result in a never ending arms race of
throttling. Inevitably, that phone _and_ battery would be in the landfill
instead of just the latter.

Whether or not the whole thing was intentionally nefarious I'm not convinced.
But the episode _looks_ way worse than your comment suggests.

~~~
jki275
Are you suggesting it wasn’t known that battery replacements were available
for iPhones? I know I personally replaced several batteries over the years in
iPhones, I don’t think that was a big secret. There were shops you could drop
your phone off at and have anew battery put in for fifty bucks in an hour
overseas at least.

~~~
schadara
Apple didn't inform users that battery replacements would make their sluggish
phones fast again.

~~~
acdha
More accurately, Apple didn’t have a UI notification. This was not a secret
and support people recommended it if you actually contacted them.

~~~
mthoms
>This was not a secret and support people recommended it if you actually
contacted them.

False. The retail and support staff were not informed of the throttling. See
my other comment.

~~~
acdha
True, as personally witnessed.

~~~
mthoms
Besides your singular anecdote, do you have any evidence that frontline staff
were notified of throttling? Everything that's come out so far says otherwise.
It's a key part of the class action lawsuit to which Apple agreed to settle.

It's possible that some staff deduced that replacing the battery would help,
based on personal observations, but they were never advised by corporate to do
this as policy. As such, the vast majority of them were not recommending
battery replacements.

You must have got lucky.

------
Qasaur
I always wondered why the microphone on my MacBook Pro would stop working
whenever I closed the lid when using my external monitor. Glad to hear the
"bug" exists for good reasons.

~~~
DaiPlusPlus
What are users meant to do if they _want_ to use their Mac's microphone while
the laptop lid is closed?

~~~
nullc
I remember years ago visiting a customer shortly after many of their
engineering staff had just upgraded to whatever macbook was popular at a time.

Within the week that they had them, two people in the department had broken
their screens/hinges from accidents walking in and out of meetings with the
lids open because there was no way provided in the software to disable suspend
on lid closed which was killing people's SSH sessions. Within the month
someone in my office also managed to do the same, and most of us weren't even
using macs.

(I understand that this was eventually workaroundable with some power users
tools; and I imagine mosh makes the suspends a little less of an issue now).

I'm sad that the popular linux desktops later decided to emulate the bad
software culture that brought anti-features like that mandatory suspend.

So I expect that mic off on hinge close will have similar results. Though, ...
at least this seems a lot more legitimate to me than a refusal to not suspend.

~~~
mvanbaak
A macbook works perfectly in clamshell mode. Just provide power and have a
display connected. (not sure if you have to have a display connected, but it's
how I'm typing this comment right now)

Also, using tmux (or screen) on the other end of the ssh connection helps. And
not only for when you close the lid, but also if the connection gets
interrupted (power failure, internet failure, routing failure, whatever)

~~~
toast0
> A macbook works perfectly in clamshell mode. Just provide power and have a
> display connected.

I can't imagine how much more equipment would be damaged if the people
described were carrying around a power source and a monitor with them so they
could close their laptop and bring it to a meeting without dropping their
sessions.

~~~
folmar
There are fake display adapters specifically to combat stupid problems with
running mac displayless. Maybe we need a fake power source as well...

------
pulse7
I would rather have a physical (manual) switch to disconnect the power to the
microphone and camera hardware on all my devices (laptop, phone, ...). This
way there would be no need to trust the Security Chip and there would be no
attack vectors and possible future zero-day attacks on the security chip...

~~~
bb123
That’s fair enough but you have to accept you’re in the huge minority there.
The average consumer does not want to have to flip a switch for every
microphone on their devices when they want to use it. Not to mention the
reliability implications of adding more moving parts and dust/water ingress
points. There has to be a trade off between usability and security.

~~~
karatestomp
My teacher wife and a bunch of the folks she knows (non-nerds) cover their
webcams with stickers or whatever. They’d all love (separate!) kill-switches
for their cameras and mics. Plus everyone working in tech I know. So that’s...
everyone I know who’s aware their laptops have cameras and microphones.

~~~
reaperducer
I think you're overstating your position.

If all of those people had to flip a hardware switch every time they wanted to
use their phones, they'd complain about it.

~~~
folmar
On a laptop it may often be once in a lifetime.

~~~
reaperducer
Depends on your laptop. My Mac laptops ring when someone calls my phone in
another room.

------
nicebill8
> All Mac portables with the Apple T2 Security Chip feature a hardware
> disconnect that ensures the microphone is disabled whenever the lid is
> closed.

vs.

> On the 13-inch MacBook Pro and MacBook Air computers with the T2 chip, and
> on the 15-inch MacBook Pro portables from 2019 or later, this disconnect is
> implemented in hardware alone.

Do these statements not contradict each other for the 15" 2018 MacBook Pro,
for example, which includes a T2 chip? This would also contradict earlier
documentation provided on the T2 chip by Apple themselves [1].

From [1]:

> All Mac portables with the Apple T2 Security Chip feature a hardware
> disconnect that ensures that the microphone is disabled whenever the lid is
> closed. This disconnect is implemented in hardware alone, and therefore
> prevents any software, even with root or kernel privileges in macOS, and
> even the software on the T2 chip, from engaging the microphone when the lid
> is closed.

[1]
[https://www.apple.com/euro/mac/shared/docs/Apple_T2_Security...](https://www.apple.com/euro/mac/shared/docs/Apple_T2_Security_Chip_Overview.pdf)
(October 2018, page 13)

~~~
alias_neo
I don't think they contradict each other. The way I read it is, the former,
have hardware disconnects controlled by some software/firmware, such as a
relay/MOSFET or something of that kind; an electronic switch.

The latter I read as being hardware _only_; "only" being the key addition to
this sentence. I would expect this implementation to be something like a reed
switch to magnetically disconnect the lines _physically_ rather than
electronically.

~~~
ken
Isn't the whole point of software to control hardware, at some level? How is
hardware-controlled-by-software different from plain old software-controlled?
If a switch can be closed by software, I'm having trouble putting my finger on
exactly what security benefit that might offer.

~~~
derefr
> How is hardware-controlled-by-software different from plain old software-
> controlled?

Perhaps it’s that the hardware interlock on the microphone can be _enabled_ by
software, but can only be _disabled_ by a physical action (i.e. opening the
lid.)

------
_bxg1
Apple in 2020 is such a weird thing. Some of the things they produce - mostly
in the software realm, I guess - have really careless and egregious bugs and
design problems. But then they still come out and make amazing little features
like this one that nobody thought to ask for, and don't get highly publicized,
but really speak to that classic detail-oriented Apple mindset.

It's like there's a huge cultural schism running through the middle of the
company, or something.

~~~
zionic
Is it too much to ask for a small LED next to each camera indicating if the
sensor is powered? Should be standard on every phone.

~~~
artiscode
Ditto. Or even an old-school LED that indicates data transmission like the HDD
LED in old computer cases. Make it in hardware so that if any data is sent
through the wire, it lights up.

~~~
jachee
People already complain about the price and battery life of current phones. I
can’t imagine either of those things making either situation better.

~~~
dandelany
You can get SMD 0603 LEDs that use ~1mA of power for a few pennies in bulk.
Peanuts compared to the power usage and price of the rest of the phone.

------
Edd314159
> iPad models beginning in 2020 also feature the hardware microphone
> disconnect. When an MFI compliant case (including those sold by Apple) is
> attached to the iPad and closed, the microphone is disconnected in hardware

does this mean Hey Siri won't work on an iPad with a closed cover?

~~~
randyrand
Doesn't MFI use software to do verification? If the presence of a MFI software
command is what disables and enables the microphone, that sure sounds like
software control.

Sure, maybe its software on a peripheral that controls it. But it's software
never the less.

~~~
lilyball
I expect in this case it's a matter of having magnets in the correct locations
as specified by MFI.

------
mikece
Why doesn’t Apple have an option for buying a MacBook Pro with the camera and
mic physically disconnected? They could sell this option at an appropriately
priced premium — along with a stylish Bluetooth-connected, 4K webcam with
phased array mics for a very reasonably $499. I’m sure they would sell
hundreds of thousands of them.

If ANYBODY could monetize “security chic” it’s Apple.

~~~
frosted-flakes
How hard is it to stick a piece of tape over the camera and super-glue the
microphone?

~~~
mikece
The underlying sensors are still active. I typically just keep my Logitech
G430 headphones -- with the physical mute switch active -- plugged into my
computer at all times because the system uses that for sound capture... except
Siri/Cortana/Ubuntu One hear nothing when those are plugged in.

------
anonymousiam
Does it really matter if they have a hardware disconnect, when the hardware
disconnect is controlled by software? It's not truly a hardware disconnect
unless there's a physical switch that the user can flip on or off.

~~~
elliottkember
> On the 13-inch MacBook Pro and MacBook Air computers with the T2 chip, and
> on the 15-inch MacBook Pro portables from 2019 or later, this disconnect is
> implemented in hardware alone.

------
bschwindHN
Perhaps this is the hardware people are speculating about with magnetic
switches?

[https://www.ifixit.com/News/33952/apple-put-a-hinge-
sensor-i...](https://www.ifixit.com/News/33952/apple-put-a-hinge-sensor-in-
the-16-macbook-pro-what-could-it-be-for)

Though it seems their "hardware only" solution was on earlier models than
that, so maybe not.

------
1f60c
> _(The camera is not disconnected in hardware, because its field of view is
> completely obstructed with the lid closed.)_

I love this aside xD

------
qwertox
Why not a manual switch? I rarely use the microphone on those devices.

~~~
thih9
This would result in a different UX.

Users would have to remember about turning it on/off, many would forget,
leading to frustration.

Also Apple would have to place that manual switch somewhere, this would change
the device's interface.

~~~
knute
I once had a laptop with a manual switch for the wifi. Its sole purpose, as
far as I could tell, was to get accidentally bumped and cause me to waste time
figuring out why wifi wasn't working.

~~~
Swenrekcah
I feel you, but there would be a really easy solution to that, just make it
clear with the network connectivity icon that the hardware switch is off.
Don’t know why it hasn’t been done.

~~~
simonh
It would require Microsoft to standardise the interface and specifications for
manual wifi switches, and certify and police compliance, to make sure the
hardware and software worked properly together. For Apple this sort of
coordination across teams is routine and simply the way everything works, but
for Microsoft and its hardware OEMs it's a serious time consuming and
expensive pain.

~~~
Swenrekcah
Thanks, I hadn’t thought of that.

------
hwc
I'd rather have a manual switch for both the microphone and the camera.

~~~
adrianmonk
I would too, on every device, but I don't know how the industry is going to
get past two barriers to achieving this:

1\. It costs a little bit of money, and hardware designers love to minimize
costs and eliminate parts.

2\. It's not idiot-proof enough for a lot of people. You're going to have
people who can't find the switch. And who complain and generate support costs.
And annoy their coworkers by being muted during video conferences.

Maybe you could fix the second one by having a flashing light on the switch
that says, "Please switch this switch! The microphone is needed!" This could
also increase awareness of when things are trying to use the microphone.
although it would go against the first point because it's yet another part.

------
jacquesm
They do not reveal how this is implemented at the physical level. I'd think
such a statement should be accompanied by a circuit diagram.

The simplest and most fool proof method is a physical switch that interrupts
the mic lead. If you want it to be 'pop and crackle' free you may have to
fiddle a bit or use a make-before-break switch and connect the other line to
ground. No amount of software hacking will get around that, and the position
of the switch is good feedback that you are not open to eavesdropping.
Anything less than that is likely hackable in some way or other.

------
sneak
And yet they’re still not encrypting iCloud Backups in a way that doesn’t
allow Apple (and by extension the federal police) unfettered access to spying
on iMessage. iCloud Backup is on by default, so this means that iMessage for
almost every iPhone user is insecure. Incongruent.

[https://www.reuters.com/article/us-apple-fbi-icloud-
exclusiv...](https://www.reuters.com/article/us-apple-fbi-icloud-
exclusive/exclusive-apple-dropped-plan-for-encrypting-backups-after-fbi-
complained-sources-idUSKBN1ZK1CT)

------
tachyonbeam
Would also be nice to have little hardware LEDs that automatically turn on
when the microphone or camera are connected. That way you are sure to know if
they are recording.

------
x775
I did not realise this feature existed. Am pleasantly surprised.

------
morpheuskafka
This may be Apple's first real response to the checkm8 vulnerability. It had
already been fixed on the current iOS devices as of its disclosure, but the T2
chip is still shipping (and is currently on computers that will last for a
decade versus phones that last two years) with no fix AFAIK.

Apple could fix T2s going forward, but it would require a BootROM change not
just a software update.

------
jasoneckert
So, the next target for malware creators would be to attack the software that
communicates a "lid closed" event to the T2 chip.

~~~
chithanh
There exist easier targets, such as the loudspeakers which can be turned into
microphones.

[https://www.usenix.org/system/files/conference/woot17/woot17...](https://www.usenix.org/system/files/conference/woot17/woot17-paper-
guri.pdf)

------
jokit
Is there any chance this is true? If so, is there a way to trick the hardware
into switching microphone off, even while being used?

~~~
LeoPanthera
It’s a physical magnetic switch. The article does explain this.

~~~
randyrand
But magnet does not appear in the article?

------
dorongrinstein
I asked my Alexa if this is true, but she didn't know. Anyway, this article
makes me feel safer. I'll keep my Mac shut.

------
mkchoi212
Hmmm I wonder if anyone has done a teardown of the MacBook to show how these
microphone disconnect mechanisms work.

------
walterbell
Feature request: iOS system-wide option to disable all optical cameras. FaceID
can continue to use the IR camera.

------
placard
This is not enough, the sane solution needs physical switches like the Lenovo
T400 had for WiFi.

Where are the real laptops? I'm tired of the glossy short screens, lack of
ethernet connections and crappy keyboards (this applies both to Lenovo and
Apple).

~~~
folmar
Thou shall follow the FrankenPad route.

~~~
kyuudou
Works for the ISS and OpenBSD users

------
enriquto
Why is apple so allergic to physical switches, directly switchable by the
user?

~~~
lotsofpulp
I’m guessing easier to break, causes more troubleshooting issues, looks
cleaner without it. The less moving components there are, the less warranty
and tech support they probably have to field too.

Swapping out devices is probably less costly than fixing parts of it.

~~~
enriquto
Depending on your point of view, only the second "reason" is true.

Software switches like the one described in the article (despite its name) are
definitely easier to break since they can be hacked by software. No need to
have physical access to the computer. A discrete switch definitely looks
cleaner than a piece of duct tape, and is much easier to turn on/off. If you
want to "switch off" your mic, bad luck.

------
mulmen
This is pretty cool. Can I interact with the switch directly? Can I use a
little magnet to trip the switch on an iPad? Or a mac? What about iPhones, do
those have hardware disconnects too?

------
throwawaysea
I think this is a positive thing and like the idea of being protected even if
the machine is compromised. However I would still prefer the convenience of a
switch in addition to this.

------
abinaya_rl
Any idea does other manufacturers does this? Dell or Lenovo?

I'm impressed with Apple's attention to details like this! ️

------
fortran77
My Lenovo Laptop has a little physical shutter you can slide over the camera.
It's very handy.

------
augustl
Does other manufacturers does this?

Maybe it's a standard thing that Dell, HP and others do as well?

~~~
mikro2nd
Purism do hardware switches for mic/camera and wifi on their Librem range.
(Wish I could afford one of those machines!)

------
randyrand
Begs the question - how do they detect the lid is closed? In software? :P

~~~
elliottkember
Magnets!

------
tudorizer
Hold on. How is this hardware? Is there a physical button/hinge that is
triggered? If so, the chip shouldn't matter.

Or is this some piece of logic emebedded in the chip itself or the firmware of
some other component, which makes this solution a software one.

~~~
paxswill
My understanding is that the chip is a proxy for when they started including
it in the design. Similar to how some older macOS/OS X releases had
requirements like, "faster than 867MHz", or "newer than 2012" instead of, "GPU
must support Quartz Extreme" or "CPU must support XYZ instructions".

------
swebs
But how am I supposed to use my computer when the lid is closed?

~~~
jaywalk
With an external microphone, if you need it.

~~~
swebs
I think you misunderstand. I want to use my computer normally while the
microphone and camera are disabled.

------
z5h
"The camera is not disconnected in hardware, because its field of view is
completely obstructed with the lid closed".

How long until someone realizes audio data can be extracted by from the noise
generated by a camera in the dark?

~~~
InitialLastName
Source? Not because I disbelieve that it's possible in practice, but how much
data can you really get out of that? A MacBook Pro camera operates at 60 Hz;
unless you can interpolate samples some way I'm not thinking of (and that
would necessarily degrade your resolution), the highest frequency you can
capture is 30 Hz. Technically, this could be extracting audio, but it's not
audio that meaningfully overlaps with the human experience.

~~~
z5h
No source, but there’s just been such a long history of side channel attacks,
and similar research ([https://nofilmschool.com/2014/08/mit-extract-sound-
audio-sil...](https://nofilmschool.com/2014/08/mit-extract-sound-audio-silent-
video-picture-information)) that it makes one wonder if a non-hardware
disconnect fix is sufficient.

~~~
ricardobeat
> high-speed camera that captured 2,000 to 6,000 frames per second

~~~
z5h
Literally the next lines

> In other experiments, however, they used an ordinary digital camera. Because
> of a quirk in the design of most cameras’ sensors, the researchers were able
> to infer information about high-frequency vibrations even from video
> recorded at a standard 60 frames per second.

------
neycoda
But I want to hardware disable it at any time...

------
6d6b73
How about disconnecting it when you're near the laptop and the lid is open
because you're .. I don't know... working on it?

------
dvfjsdhgfv
great! now give us back the hardware switch

------
amelius
We only get guaranteed privacy when the lid is closed?

~~~
danieldk
The problem is that otherwise "Hey Siri" wouldn't work on (newer) Macs. Still,
you can use something like Micro Snitch to track webcam/mic use.

Also, in macOS Catalina (I don't remember if this was the case in prior
versions), applications are not permitted by default to use the mic or camera
and have to request permission.

These are perhaps not as good as a hardware disconnect, but I think Apple is
trying to balance privacy and usability here. It is clear from what Apple is
doing in hardware and software that they do care about privacy. Linux and
AFAIK Windows do not provide that level of privacy, since applications have
unfettered access to Cameras and Mics.

(Of course, a part of the Linux community is trying to improve this through
Pipewire, Flatpak, and portals.)

~~~
fnord123
>The problem is that otherwise "Hey Siri" wouldn't work on (newer) Macs.

I've never heard anyone use Siri on their Mac. I'm surprised they still bother
supporting it.

~~~
OliverM
I use it all the time. It's a great additional channel for commands in some
workflows.

~~~
fnord123
Can you give some examples? The only way I can think it's helpful is for hands
free use, but that's more a scenario for a phone or tablet rather than a
laptop.

~~~
Reason077
Adding reminders is the only thing I ever use it for. They carry across to the
iPhone, of course, so if I need to remind myself to do something later in the
day it's quite helpful.

I'd use it to set timers, too (by far the most frequent thing I use Siri for
on iPhone) but annoyingly that doesn't work from the Mac.

