Apple's T2 chip will prevent hackers from eavesdropping on your microphone • Hacker News Board

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#111

Post by klodolph » Mon, Nov 05, 2018, 3:15 AM UTC

shawnz wrote: post #56

GuB-42 wrote: post #24

Earlier quoted context omitted.

There is already a lid closed sensor. Adding another mechanical switch is more expensive, adds another point of failure, takes space, may interfere with the aesthetics, etc... The T2 chip probably also acts as a controller for a lot of the builtin sensors, including the microphone and lid closed switch. As a result, adding a feature to turn off the microphone when the lid is closed becomes trivial. Basically just add…

Why have the control go through a sophisticated programmable chip and not just use a simple transistor/relay directly connected to the sensor?

A “simple” transistor or relay is bulky and expensive. By comparison, routing through a programmable chip (which is already on the board) is nothing more than routing work—it doesn’t add anything to the BOM.

This is just the way people design circuits these days, because it’s easier and cheaper. A single µC with a few GPIOs, rather than a bunch of logic chips scattered around the board.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#112

Post by klodolph » Mon, Nov 05, 2018, 3:26 AM UTC

petee wrote: post #101

scarface74 wrote: post #70

Earlier quoted context omitted.

The T2 is used for: - image signal processing - an audio controller - a mass storage controller - a dedicated AES engine for encryption. - secure enclave for touch id

Jeez, sounds like the T2 is prime to be merged into systemd. Someday we'll find that the image processing function has a bug that lets you control the microphone when you open some stupid meme. Great separation of security

Running on the same chip does not mean that there’s no isolation. The T2 has an ARM core with an MMU, different processes can be isolated from one another as well as you can on ordinary OSs. Given that you can’t load software on the T2 you’d have to find some remote hole and then do local privilege escalation.

And still certain things will be impossible, even if you control the software on the T2, because there is no hardware access to e.g. read the encryption keys, from what I understand.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#113

Post by dpkonofa » Mon, Nov 05, 2018, 3:27 AM UTC

snacktaster wrote: post #71

dpkonofa wrote: post #63

Earlier quoted context omitted.

The camera already functions this way. The light is connected to the actual power of the camera and cannot be disabled unless the camera is also disabled. The microphone, to my knowledge, doesn't function like this but I don't think it makes sense for it to function like this as the microphone doesn't really need power outside of what's provided to the amps and DACs inside the machine. It would be too easy to work ar…

> The light is connected to the actual power of the camera and cannot be disabled unless the camera is also disabled. This was proven false when malware was discovered that accessed the camera on Mac laptops without activating the LED light. It's mentioned in the article.

This was not proven false. The malware that was discovered only affected iMacs and MacBooks from 2008 and prior when the light was not directly connected to the camera's power. That didn't happen until early 2009.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#114

Post by klodolph » Mon, Nov 05, 2018, 3:32 AM UTC

I think we’re finally at the point where hardware isolation is a standard part of our defense in depth, just like ASLR and W^X. I’d like to see these exposed in more consistent ways to software. T2 should be able to provide U2F, it’s too bad it doesn’t.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#115

Post by bdamm » Mon, Nov 05, 2018, 3:34 AM UTC

djrogers wrote: post #81

ridgeguy wrote: post #75

Earlier quoted context omitted.

Physical switch could be done with a very small magnet behind the lid surface and an opposed micro-reed switch (or other magnetically actuated on/off device) buried behind the body surface. No surface penetrations, no exposed moving parts (reed relays are hermetically sealed).

And a magnetic switch is far too easily defeated

How? The point is to prevent invisible eavesdropping not prevent some spook on the table from hacking you.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#116

Post by modzu » Mon, Nov 05, 2018, 3:39 AM UTC

alphabettsy wrote: post #72

modzu wrote: post #59

Earlier quoted context omitted.

too easy to fix if it breaks

A switch is more likely to break than a sensor and there’s already one for closed lid.

theres just no lolz round here

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#117

Post by brirec » Mon, Nov 05, 2018, 3:47 AM UTC

ridgeguy wrote: post #75

pulse7 wrote: post #53

Earlier quoted context omitted.

Physical switch could be made INSIDE the laptop and would be automatically pressed by the lid itself - when the lid is closed. No sensors needed. No chip needed. When lid is closed - mic is disconnected. When opened - mic is connected... User does not need to do anything else then closing the lid...

Physical switch could be done with a very small magnet behind the lid surface and an opposed micro-reed switch (or other magnetically actuated on/off device) buried behind the body surface. No surface penetrations, no exposed moving parts (reed relays are hermetically sealed).

Reed switches are pretty damned huge when working at the scale of a laptop.

Not to mention it would make the case of the computer microphonic — bump it hard enough and that’ll be transmitted through the reed relay.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#118

Post by jfrankamp » Mon, Nov 05, 2018, 4:18 AM UTC

I'm shocked at how many defenders pop up here for a proprietary chip that cannot be audited. Sure, this hardware/firmware combo might be safe. It also might be terrible, but no one on this thread actually knows either way. It is also vulnerable in ways that a magnetic lid switch would never be. The T2 is the single most important attack target (for desktops) now for large budget attackers. I wonder how long until the HN headline reads T2 vulnerability found.

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#119

Post by justapassenger » Mon, Nov 05, 2018, 4:18 AM UTC

klodolph wrote: post #112

petee wrote: post #101

Earlier quoted context omitted.

Jeez, sounds like the T2 is prime to be merged into systemd. Someday we'll find that the image processing function has a bug that lets you control the microphone when you open some stupid meme. Great separation of security

Running on the same chip does not mean that there’s no isolation. The T2 has an ARM core with an MMU, different processes can be isolated from one another as well as you can on ordinary OSs. Given that you can’t load software on the T2 you’d have to find some remote hole and then do local privilege escalation. And still certain things will be impossible, even if you control the software on the T2, because there is no…

Phew, that's a solid model! No software ever had both remote holes and local privilege escalation!

Re: Apple's T2 chip will prevent hackers from eavesdropping on your microphone

#120

Post by Johnny555 » Mon, Nov 05, 2018, 4:34 AM UTC

dom96 wrote: post #86

pulse7 wrote: post #53

Earlier quoted context omitted.

Physical switch could be made INSIDE the laptop and would be automatically pressed by the lid itself - when the lid is closed. No sensors needed. No chip needed. When lid is closed - mic is disconnected. When opened - mic is connected... User does not need to do anything else then closing the lid...

There are people out there that hook up their laptop to an external display and then use it with the lid closed. Wouldn't be surprised if some of them want to use the mic with that configuration as well.

Then they are out of luck with this new T4 security chip cutoff, Apple says that it cuts off the mic when the laptop is closed, and there's no way even the kernel can override it:

“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,” said the support guide.

So in this respect, there's no difference between the T2 chip cutoff and a physical switch... except that there could still be a backdoor in the T2 chip cutoff that Apple hasn't admitted to.