9 ms·

So to summarise: - Requires physical device access. - Cannot decrypt FileVault without you entering decryption key post-exploitation. - Cannot access secrets

So to summarise: - Requires physical device access. - Cannot decrypt FileVault without you entering decryption key post-exploitation. - Cannot access secrets in the Secure Enclave. This isn't great, but it's not really a huge security issue? The main attack vector here is stolen Macs being re-sold as they can be "un-bricked". I know part of the point of the T2 is to make physical access less interesting an attack vector, but it's typically doing so after a machine has been stolen. This makes it more attractive to do without stealing, but that's an attack style that is only really done by state level threats, and one that was still possible anyway, because hardware access is essentially game-over anyway at that point. I feel like this is over-blown? Am I missing something? Is there another attack vector here that's worse for "regular users"?

totaldude87 6y ago
right on Spot, but also brings an ethical question ! lets say you identified an vulnerability or an hack or found something that will nullify a product's security. what would be the first step one should do? 1). send it to apple(or respective company) and if they don't respond after followups, put it on internet 2) put it on internet so it gains popularity and makes the aforesaid companies do something! in some cases like these (those require physical access) this is fine, but what if someone uncovers a potential remote hack for every android or apple phone out there! which option would be ethical?
- pmx 6y ago
  The right thing to do is follow Responsible Disclosure https://www.bugcrowd.com/resource/what-is-responsible-disclosure/ https://www.bugcrowd.com/resource/what-is-responsible-disclo...
- userbinator 6y ago
  I'd say it depends on what that "security" is. If it is remotely exploitable and can harm user freedom, tell the companies quietly. On the other hand, if it can enable user freedom, keep it to yourself and those who you trust to be on your side.
rocqua 6y ago
What I thought from previous articles is that this helps brute forcing passwords. Note that I do not know this for sure. My thought was that the T2 chip is responsible for rate-limiting access to the Secure Enclave. Specifically, for rate-limiting attempts to derive a key from as user-supplied password and the secret in the Secure Enclave. This allows for weaker passwords to be used, because brute-forcing requires the secure-enclave in the loop, and access to that enclave is rate-limited. Drop that rate-limiting, and the brute-force attack becomes a lot more viable. As far as I know, this was at stake when the FBI wanted apple's help a while ago to decrypt an Iphone. However, I have no idea whether this is the same scheme used for MacOS devices. Nor do I know whether the T2 chip is actually responsible for rate-limiting.
- philistine 6y ago
  I think the rate-limiting is done in hardware by the Secure Enclave itself. It cannot physically respond any faster than it does right now.
  - 95014_refugee 6y ago
    This is correct.
logicOnly 6y ago
It's a huge security issue. Physical device access is reasonable. Stolen phones, people incarcerated, etc.... How difficult would it be to steal someone's phone, but illegal stuff on it, and call the police? Could you figure it out for 10k USD?
- deleted 6y ago
  [deleted]
- donor20 6y ago
  I'm continually reminded that a HN "HUGE!!" security issue is so rarely that. I can think of so many more much more significant security issue, from remote root access to windows machines, potentially intentionally flawed VPN security, TPM on intel machines that are remotely exploitable and provide persistent access to machine and the list goes on and on. There is something about Apple that makes folks blow up. Perhaps it's just they are one of the few with a bit of a reasonable reputation here. Steal someone's phone? You realize iphones since Xs forward are using A12+ chips, they don't even have the intel / T2 combo being talked about as far as I know. And then to get access you need to install a keylogger PHYSCIALLY into the macbook. All this is "possible", but you can probably do a keylogger without breaking T2 and get equivalent access at the end of the day.
  - ziml77 6y ago
    I think a lot of people are looking for any reason to put Apple down. I'm guessing it's both because Apple and its users love to brag about security and because HN users hate the cost that you pay for that security: a device locked down from its own owner.
    - donor20 6y ago
      That is true - apple is locking everyone out - including the person who paid for it. But that does make the iphone relatively better from a security standpoint. The overseas android market is a wasteland security side - no one even pretends, they don't even keep the phones updated.
JAlexoid 6y ago
Regular users don't care about security - that's just a matter of fact. As for security for "other users" - users with high security requirements can be targeted, even with a locked system. As an example - if someone messes with my laptop while I'm away, TPM will fail and Windows will demand I re-enter my bitlocker key upon start. If you can suppress that - that's a big issue.
- danpalmer 6y ago
  > Regular users don't care about security They don't care enough to be inconvenienced for it, but they do care when their identity is stolen, when they are blackmailed with photos, etc. This is what's good about the T2, it secures those sorts of things for regular users in a very convenient way. This vulnerability does not appear to really change that for regular users (although it likely does for orgs with high security requirements, i.e. those considering an APT part of their threat model).
CivBase 6y ago
> Requires physical device access. For what it's worth, we're talking about mostly personal laptops, tablets, and smartphones here - not corporate servers. I wouldn't be so quick to dismiss the "physical access" requirement, although that does at least make it difficult for attackers to exploit the vulnerability at a large scale.
- sprayk 6y ago
  physically target the macbooks of employees that have access to those servers, especially the enterprise device management servers, and you can probably exploit this at a larger scale. You could do a pretty trivial amount of LinkedIn research to figure out your targets.
- danpalmer 6y ago
  Sure, but as mentioned there are basically 2 versions: steal, or modify in place. With the former, the device is already stolen. The only difference here is that the thief can re-sell it. That's not a huge win for the user who it was stolen from. With the latter, you need ongoing physical access in order to install and maintain a presence on the device. That's a sophisticated attack, but sophisticated attackers already have ways of doing this.
  - ampdepolymerase 6y ago
    Or version 3, the powers that be ask you nicely to hand over your device. The fourth and fifth offers only very limited protection in the digital sphere and current precedents on decryption and access can easily be overrode by courts.
    - nkrisc 6y ago
      Yes, they mention that in their original post: > This makes it more attractive to do without stealing, but that's an attack style that is only really done by state level threats, and one that was still possible anyway, because hardware access is essentially game-over anyway at that point.
  - 6y ago
czbond 6y ago
I agree with you. Question for the group, since hardware security isn't my area. Will Apple be able to update this vulnerable in a T2.1 or T3? Gives me a new reason for yet another MBP I guess (just purchased the 16")
- zitterbewegung 6y ago
  T2 is basically a bridge (EDIT: as others have pointed out for this term I meant a temporary fix for non ARM Macs) between Intel Macs and Arm Macs to allow for macOS 11 to work on both platforms with feature parity such as Siri. Its probably a good idea to get a new Arm Mac as your next Macbook Pro because the T2 chip doesn't even need to be there anymore.
  - czbond 6y ago
    Danke - that was enlightening. Would never have known those - great quick analysis.
  - djrogers 6y ago
    That’s not at all what the T2 is. It’s a multi-purpose processor that handles some security related services (like the Secure Enclave), acts as the SSD controller, handles the camera light, touchID, and other stuff. It’s not there as a ‘bridge’ - plenty of macs without T2 processors run macOS 11 and Siri with full feature parity, and neither of those things relies on the T2.
    - derefr 6y ago
      What the GP is saying is that the T2 is effectively “the processor” of Macs it’s in, in the sense that it’s performing the function of a System Management Controller, managing early boot, etc. The Intel CPU in these systems is reduced to being an “application processor”—much like in ARM systems where boot and IO are handled through the GPU. (This is why you can’t install OSes other than macOS on these devices. It’s not because of DRM or anything—though that’s an aspect of it. Rather, it’s because the T2 is in control of boot, and no other OS has had a second-stage bootloader written for it that will load onto the T2 chip to do hardware bringup from that side.) Maybe “bridge” is the wrong word here—though I can see the meaning. A precise term, I think, would be “polyfill.” The T2 is the place where Apple is putting 1. its IP-core customizations that it can’t just plop into the Intel CPU, because it doesn’t control the Intel CPU; and 2. its top-level “BIOS-alike”, allowing them to bring up the hardware in a way they control, rather than having to convince the Intel CPU to do it in a way it understands. The T2 and the Intel CPU acting together, roughly simulates an architecture akin to that of an ARM Mac (as with any other polyfill, where the old runtime and the polyfill acting together roughly simulate the capabilities of the new runtime.) The interesting thing about this, is that it’s likely that because the polyfill roughly simulates the environment of an ARM mac (where these IP cores are accessible directly through the CPU, and where hardware bringup is always done in Apple’s preferred fashion without having to trick the Intel CPU into it), the drivers written for Intel-plus-T2 macOS, are also likely able to be run with only small changes, directly on ARM macOS. That’s why the GP is calling the T2 a “bridge”: it’s a half-step across the chasm between the archtectures; an intermediate architectural target that allows some but not all of the work of developing ARM macOS to be done before any Apple Silicon ARM platforms like the A14Z were actually available to be developed on.
Cthulhu_ 6y ago
It's probably not something an average joe will have to worry about, but it'll definitely be interesting for state agents, secret services, etc.
yannikyeo 6y ago
When you send your Mac to Apple Support, it is assumed that no technician is able to peep at your data, as T2 provide encrypted storage on SSD. With this loop hole, your data is wide open eg when your Mac die before you can wipe your data. Apple often would replace the whole Mac, including new SSD for you. Those who skip FileVault might want to reconsider.
ogre_codes 6y ago
It's a good idea to assume that if physical access is compromised, you are screwed. This just confirms this continues to be the case. Even without this, many people could be owned just by installing a key logger on their external keyboard which would likely be easier to access and hack than the T2/ laptop.
donor20 6y ago
I think to persist the attack you need a persistent hardware device attached so a reboot doesn't reset things? The thing is, can't you just stick a keylogger onto the machine at this point and get an equivalent compromise? I log you login and then use that to authenticate?
NotSammyHagar 6y ago
Every time an apple device is taken from you at the us border, the border patrol could use this vector to capture your password later and send it over the internet without your knowledge. Before you could just assume they couldn't infect you. You aren't safe until you reset the t2 - every time someone takes it from you.
- olliej 6y ago
  But the same is true for any laptop - if someone untrustworthy takes your laptop and you’re at that level of concern then your next step is necessarily erasing the machine.
- danpalmer 6y ago
  Since this is a tethered exploit, simply rebooting the device should prevent that. They could also install a hardware keylogger, so a non-exploitable T2 doesn't really help here in the general case. We just have to hope that the TSA aren't at the level of your average state actor.
  - dimensi0nal 6y ago
    rebooting the mac doesn't reboot the T2
rangoon626 6y ago
It just means that including the T2 chip adds more locks that half work for criminals, but locks that fully work for casual users.
GeekyBear 6y ago
It's the same Checkm8 exploit that was hyped up as the end of the world for iPhones late last year (before it turned out that it was really only useful to allow sideloading software on your own device). https://arstechnica.com/information-technology/2019/09/developer-of-checkm8-explains-why-idevice-jailbreak-exploit-is-a-game-changer/ https://arstechnica.com/information-technology/2019/09/devel...
- saagarjha 6y ago
  This is a fairly uncharitable description of the exploit.
throwaway840274 6y ago
True that physical possession lowers the risk barrier considerably, but still this threat is problematic in a couple of ways. a) An unattended laptop can be compromised in under five mins, all without any obvious indications. There are also loaner situations, at schools etc. where machines are shared. b) no specialized hardware is necessary, so it's really cheap to execute. c) this is probably the worst part - power cycling the laptop does not reset the T2 ("The T2 chip is fully booted and stays on, even if your Mac device is shutdown.") - so there's no practical way to ensure that your machine is not compromised after a brief interlude. For extra fun, if it turns out the attack can be executed by a malicious wall port, then things start to get really interesting.

totaldude87 6y ago

right on Spot, but also brings an ethical question ! lets say you identified an vulnerability or an hack or found something that will nullify a product's security. what would be the first step one should do? 1). send it to apple(or respective company) and if they don't respond after followups, put it on internet 2) put it on internet so it gains popularity and makes the aforesaid companies do something! in some cases like these (those require physical access) this is fine, but what if someone uncovers a potential remote hack for every android or apple phone out there! which option would be ethical?

pmx 6y ago
The right thing to do is follow Responsible Disclosure https://www.bugcrowd.com/resource/what-is-responsible-disclosure/ https://www.bugcrowd.com/resource/what-is-responsible-disclo...
userbinator 6y ago
I'd say it depends on what that "security" is. If it is remotely exploitable and can harm user freedom, tell the companies quietly. On the other hand, if it can enable user freedom, keep it to yourself and those who you trust to be on your side.

rocqua 6y ago

What I thought from previous articles is that this helps brute forcing passwords. Note that I do not know this for sure. My thought was that the T2 chip is responsible for rate-limiting access to the Secure Enclave. Specifically, for rate-limiting attempts to derive a key from as user-supplied password and the secret in the Secure Enclave. This allows for weaker passwords to be used, because brute-forcing requires the secure-enclave in the loop, and access to that enclave is rate-limited. Drop that rate-limiting, and the brute-force attack becomes a lot more viable. As far as I know, this was at stake when the FBI wanted apple's help a while ago to decrypt an Iphone. However, I have no idea whether this is the same scheme used for MacOS devices. Nor do I know whether the T2 chip is actually responsible for rate-limiting.

philistine 6y ago
I think the rate-limiting is done in hardware by the Secure Enclave itself. It cannot physically respond any faster than it does right now.
- 95014_refugee 6y ago
  This is correct.

logicOnly 6y ago

It's a huge security issue. Physical device access is reasonable. Stolen phones, people incarcerated, etc.... How difficult would it be to steal someone's phone, but illegal stuff on it, and call the police? Could you figure it out for 10k USD?

deleted 6y ago
[deleted]
donor20 6y ago
I'm continually reminded that a HN "HUGE!!" security issue is so rarely that. I can think of so many more much more significant security issue, from remote root access to windows machines, potentially intentionally flawed VPN security, TPM on intel machines that are remotely exploitable and provide persistent access to machine and the list goes on and on. There is something about Apple that makes folks blow up. Perhaps it's just they are one of the few with a bit of a reasonable reputation here. Steal someone's phone? You realize iphones since Xs forward are using A12+ chips, they don't even have the intel / T2 combo being talked about as far as I know. And then to get access you need to install a keylogger PHYSCIALLY into the macbook. All this is "possible", but you can probably do a keylogger without breaking T2 and get equivalent access at the end of the day.
- ziml77 6y ago
  I think a lot of people are looking for any reason to put Apple down. I'm guessing it's both because Apple and its users love to brag about security and because HN users hate the cost that you pay for that security: a device locked down from its own owner.
  - donor20 6y ago
    That is true - apple is locking everyone out - including the person who paid for it. But that does make the iphone relatively better from a security standpoint. The overseas android market is a wasteland security side - no one even pretends, they don't even keep the phones updated.

JAlexoid 6y ago

Regular users don't care about security - that's just a matter of fact. As for security for "other users" - users with high security requirements can be targeted, even with a locked system. As an example - if someone messes with my laptop while I'm away, TPM will fail and Windows will demand I re-enter my bitlocker key upon start. If you can suppress that - that's a big issue.

danpalmer 6y ago
> Regular users don't care about security They don't care enough to be inconvenienced for it, but they do care when their identity is stolen, when they are blackmailed with photos, etc. This is what's good about the T2, it secures those sorts of things for regular users in a very convenient way. This vulnerability does not appear to really change that for regular users (although it likely does for orgs with high security requirements, i.e. those considering an APT part of their threat model).

CivBase 6y ago

> Requires physical device access. For what it's worth, we're talking about mostly personal laptops, tablets, and smartphones here - not corporate servers. I wouldn't be so quick to dismiss the "physical access" requirement, although that does at least make it difficult for attackers to exploit the vulnerability at a large scale.

sprayk 6y ago
physically target the macbooks of employees that have access to those servers, especially the enterprise device management servers, and you can probably exploit this at a larger scale. You could do a pretty trivial amount of LinkedIn research to figure out your targets.
danpalmer 6y ago
Sure, but as mentioned there are basically 2 versions: steal, or modify in place. With the former, the device is already stolen. The only difference here is that the thief can re-sell it. That's not a huge win for the user who it was stolen from. With the latter, you need ongoing physical access in order to install and maintain a presence on the device. That's a sophisticated attack, but sophisticated attackers already have ways of doing this.
- ampdepolymerase 6y ago
  Or version 3, the powers that be ask you nicely to hand over your device. The fourth and fifth offers only very limited protection in the digital sphere and current precedents on decryption and access can easily be overrode by courts.
  - nkrisc 6y ago
    Yes, they mention that in their original post: > This makes it more attractive to do without stealing, but that's an attack style that is only really done by state level threats, and one that was still possible anyway, because hardware access is essentially game-over anyway at that point.
- 6y ago

czbond 6y ago

I agree with you. Question for the group, since hardware security isn't my area. Will Apple be able to update this vulnerable in a T2.1 or T3? Gives me a new reason for yet another MBP I guess (just purchased the 16")

zitterbewegung 6y ago
T2 is basically a bridge (EDIT: as others have pointed out for this term I meant a temporary fix for non ARM Macs) between Intel Macs and Arm Macs to allow for macOS 11 to work on both platforms with feature parity such as Siri. Its probably a good idea to get a new Arm Mac as your next Macbook Pro because the T2 chip doesn't even need to be there anymore.
- czbond 6y ago
  Danke - that was enlightening. Would never have known those - great quick analysis.
- djrogers 6y ago
  That’s not at all what the T2 is. It’s a multi-purpose processor that handles some security related services (like the Secure Enclave), acts as the SSD controller, handles the camera light, touchID, and other stuff. It’s not there as a ‘bridge’ - plenty of macs without T2 processors run macOS 11 and Siri with full feature parity, and neither of those things relies on the T2.
  - derefr 6y ago
    What the GP is saying is that the T2 is effectively “the processor” of Macs it’s in, in the sense that it’s performing the function of a System Management Controller, managing early boot, etc. The Intel CPU in these systems is reduced to being an “application processor”—much like in ARM systems where boot and IO are handled through the GPU. (This is why you can’t install OSes other than macOS on these devices. It’s not because of DRM or anything—though that’s an aspect of it. Rather, it’s because the T2 is in control of boot, and no other OS has had a second-stage bootloader written for it that will load onto the T2 chip to do hardware bringup from that side.) Maybe “bridge” is the wrong word here—though I can see the meaning. A precise term, I think, would be “polyfill.” The T2 is the place where Apple is putting 1. its IP-core customizations that it can’t just plop into the Intel CPU, because it doesn’t control the Intel CPU; and 2. its top-level “BIOS-alike”, allowing them to bring up the hardware in a way they control, rather than having to convince the Intel CPU to do it in a way it understands. The T2 and the Intel CPU acting together, roughly simulates an architecture akin to that of an ARM Mac (as with any other polyfill, where the old runtime and the polyfill acting together roughly simulate the capabilities of the new runtime.) The interesting thing about this, is that it’s likely that because the polyfill roughly simulates the environment of an ARM mac (where these IP cores are accessible directly through the CPU, and where hardware bringup is always done in Apple’s preferred fashion without having to trick the Intel CPU into it), the drivers written for Intel-plus-T2 macOS, are also likely able to be run with only small changes, directly on ARM macOS. That’s why the GP is calling the T2 a “bridge”: it’s a half-step across the chasm between the archtectures; an intermediate architectural target that allows some but not all of the work of developing ARM macOS to be done before any Apple Silicon ARM platforms like the A14Z were actually available to be developed on.

Cthulhu_ 6y ago

It's probably not something an average joe will have to worry about, but it'll definitely be interesting for state agents, secret services, etc.

yannikyeo 6y ago

When you send your Mac to Apple Support, it is assumed that no technician is able to peep at your data, as T2 provide encrypted storage on SSD. With this loop hole, your data is wide open eg when your Mac die before you can wipe your data. Apple often would replace the whole Mac, including new SSD for you. Those who skip FileVault might want to reconsider.

ogre_codes 6y ago

It's a good idea to assume that if physical access is compromised, you are screwed. This just confirms this continues to be the case. Even without this, many people could be owned just by installing a key logger on their external keyboard which would likely be easier to access and hack than the T2/ laptop.

donor20 6y ago

I think to persist the attack you need a persistent hardware device attached so a reboot doesn't reset things? The thing is, can't you just stick a keylogger onto the machine at this point and get an equivalent compromise? I log you login and then use that to authenticate?

NotSammyHagar 6y ago

Every time an apple device is taken from you at the us border, the border patrol could use this vector to capture your password later and send it over the internet without your knowledge. Before you could just assume they couldn't infect you. You aren't safe until you reset the t2 - every time someone takes it from you.

olliej 6y ago
But the same is true for any laptop - if someone untrustworthy takes your laptop and you’re at that level of concern then your next step is necessarily erasing the machine.
danpalmer 6y ago
Since this is a tethered exploit, simply rebooting the device should prevent that. They could also install a hardware keylogger, so a non-exploitable T2 doesn't really help here in the general case. We just have to hope that the TSA aren't at the level of your average state actor.
- dimensi0nal 6y ago
  rebooting the mac doesn't reboot the T2

rangoon626 6y ago

It just means that including the T2 chip adds more locks that half work for criminals, but locks that fully work for casual users.

GeekyBear 6y ago

It's the same Checkm8 exploit that was hyped up as the end of the world for iPhones late last year (before it turned out that it was really only useful to allow sideloading software on your own device). https://arstechnica.com/information-technology/2019/09/developer-of-checkm8-explains-why-idevice-jailbreak-exploit-is-a-game-changer/ https://arstechnica.com/information-technology/2019/09/devel...

saagarjha 6y ago
This is a fairly uncharitable description of the exploit.

throwaway840274 6y ago

True that physical possession lowers the risk barrier considerably, but still this threat is problematic in a couple of ways. a) An unattended laptop can be compromised in under five mins, all without any obvious indications. There are also loaner situations, at schools etc. where machines are shared. b) no specialized hardware is necessary, so it's really cheap to execute. c) this is probably the worst part - power cycling the laptop does not reset the T2 ("The T2 chip is fully booted and stays on, even if your Mac device is shutdown.") - so there's no practical way to ensure that your machine is not compromised after a brief interlude. For extra fun, if it turns out the attack can be executed by a malicious wall port, then things start to get really interesting.