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Microsoft proves backdoor keys are a bad idea

theregister.co.uk

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Re: Microsoft proves backdoor keys are a bad idea

#51

Post by cptskippy »

astrodust wrote: post #23
Knuff wrote: post #7

Earlier quoted context omitted.

The point the register makes is not that this allows unlocking devices (though that's interesting in it's own right), but that is done via a "secret key" that now got exposed. Very similar to what the government wants with key escrows and other backdoor mechanisms for decryption of communication. Maybe to clarify: it highlights the mechanism (golden key) is flawed. That Microsoft uses it for boot loaders is unimporta…

In other words, if Microsoft can't keep the proverbial cat in the bag what hope do other less tech-savvy companies or organizations have?

Like the IoT makers who lock their devices by means of clear text passwords hardcoded into the device firmware?

Most companies don't go to the extent of having a cryptographically secure key validated by a TPM. At least MS is trying to secure the system.

Re: Microsoft proves backdoor keys are a bad idea

#52

Post by boznz »

IBM wrote: post #43
bradford wrote: post #5

(disclaimer, MS employee, non-security expert here). I've read through the article, here, and in other places, and I'm seeing sentiment that this is a big fuck up on Microsoft's part. I might be completely misunderstanding, but I just don't see it. In order to use the backdoor, you've got to flash firmware, so, you've got to have physical access to the device. If an attacker has physical access to your device, you're…

>If an attacker has physical access to your device, you're already screwed. The FBI had physical access to the San Bernardino iPhone. If this were true, what was the point of the public fight with Apple and eventual purchase of a zero day exploit to get into it?

I'm speculating here, but surely by this argument Apple has a backdoor to unlock the phone if it physically has it.

Re: Microsoft proves backdoor keys are a bad idea

#53

Post by cptskippy »

rdtsc wrote: post #47
bradford wrote: post #5

(disclaimer, MS employee, non-security expert here). I've read through the article, here, and in other places, and I'm seeing sentiment that this is a big fuck up on Microsoft's part. I might be completely misunderstanding, but I just don't see it. In order to use the backdoor, you've got to flash firmware, so, you've got to have physical access to the device. If an attacker has physical access to your device, you're…

Ok but then why bother with whole key thing then? That's a whole lot of code, API crap and other junk why not just force user to hold a key to specifically reboot to reflash / upgrade boot loader. So have to hold the devices in hand to do it. It seems to me the mechanism was created exactly not allow even an owner to boot a non-approved OS image.

That was exactly the intent. Service Carriers often require devices be locked because they subsidize them and want to ensure they're only/always viable with their services.

Re: Microsoft proves backdoor keys are a bad idea

#54

Post by rocqua »

bradford wrote: post #5

(disclaimer, MS employee, non-security expert here). I've read through the article, here, and in other places, and I'm seeing sentiment that this is a big fuck up on Microsoft's part. I might be completely misunderstanding, but I just don't see it. In order to use the backdoor, you've got to flash firmware, so, you've got to have physical access to the device. If an attacker has physical access to your device, you're…

Secure boot's intentions are to ensure a malicious modified OS cannot run (when taken at face value, there is also the potential for vendor lock-in, but noone will defend it based on that).

Remember that I-phone the FBI wanted apple to hack? With this golden key, anyone could've hacked into that I-phone.

I am not sure how e.g. bitlocker uses the TPM, but it might be that being able to load a modified OS allows for bypassing OS-implemented rate-limiting on TPM access.

Re: Microsoft proves backdoor keys are a bad idea

#55

Post by beagle3 »

cptskippy wrote: post #51
astrodust wrote: post #23

Earlier quoted context omitted.

In other words, if Microsoft can't keep the proverbial cat in the bag what hope do other less tech-savvy companies or organizations have?

Like the IoT makers who lock their devices by means of clear text passwords hardcoded into the device firmware? Most companies don't go to the extent of having a cryptographically secure key validated by a TPM. At least MS is trying to secure the system.

MS are trying to secure their monopoly. If they wanted to secure the system, key management would be up to the user.

Re: Microsoft proves backdoor keys are a bad idea

#56

Post by beagle3 »

boznz wrote: post #52
IBM wrote: post #43

Earlier quoted context omitted.

>If an attacker has physical access to your device, you're already screwed. The FBI had physical access to the San Bernardino iPhone. If this were true, what was the point of the public fight with Apple and eventual purchase of a zero day exploit to get into it?

I'm speculating here, but surely by this argument Apple has a backdoor to unlock the phone if it physically has it.

Of sorts. Apple (and unless they have been compromised, only Apple) could replace the firmware of a locked phone with a new firmware that will accept millions of unlock attempts without erasing the phone, at which point the password could be found by brute force.

The FBI asked Apple to create this firmware, and Apple refused.

Re: Microsoft proves backdoor keys are a bad idea

#57

Post by mindslight »

bradford wrote: post #36
pipio21 wrote: post #29

Earlier quoted context omitted.

I s there any difference between a test/development backdoor and a FBI backdoor?. If you let backdoors in the system, of course the secret services will demand to have it. In fact, backdoors that were put in place because secret services' pressure, will be suited as developer backdoors as an excuse when found by the mainstream. First they install backdoors in systems, in order for MS or the US gobertment to have comp…

I think you're missing my point (and my poor wording probably didn't help). A backdoor that requires physical access isn't a backdoor. If an attacker has such access, you're already screwed. A backdoor that requires administrative privileges isn't a backdoor. If an attacker has such access, you're already screwed. The so-called dev/test 'backdoor' really isn't a backdoor. It's a 'unlock' tool that's required for anyo…

> A backdoor that requires physical access isn't a backdoor. If an attacker has such access, you're already screwed.

The security model of "secure boot" is designed to mitigate physical access, so a private way of circumventing that property is a backdoor.

While breaking this one aspect leaves other useful security properties intact, if those properties had been the only goal, they could have been implemented with a simpler and more user-friendly system.

Re: Microsoft proves backdoor keys are a bad idea

#58

Post by qbrass »

IBM wrote: post #43
bradford wrote: post #5

(disclaimer, MS employee, non-security expert here). I've read through the article, here, and in other places, and I'm seeing sentiment that this is a big fuck up on Microsoft's part. I might be completely misunderstanding, but I just don't see it. In order to use the backdoor, you've got to flash firmware, so, you've got to have physical access to the device. If an attacker has physical access to your device, you're…

>If an attacker has physical access to your device, you're already screwed. The FBI had physical access to the San Bernardino iPhone. If this were true, what was the point of the public fight with Apple and eventual purchase of a zero day exploit to get into it?

The statement assumes the attacker knows what they're doing when they have access to the phone.

To be fair, the FBI did get into the phone, and could have much sooner had they not wasted their time fighting Apple.

Re: Microsoft proves backdoor keys are a bad idea

#59

Post by SideburnsOfDoom »

bradford wrote: post #36
pipio21 wrote: post #29

Earlier quoted context omitted.

I s there any difference between a test/development backdoor and a FBI backdoor?. If you let backdoors in the system, of course the secret services will demand to have it. In fact, backdoors that were put in place because secret services' pressure, will be suited as developer backdoors as an excuse when found by the mainstream. First they install backdoors in systems, in order for MS or the US gobertment to have comp…

I think you're missing my point (and my poor wording probably didn't help). A backdoor that requires physical access isn't a backdoor. If an attacker has such access, you're already screwed. A backdoor that requires administrative privileges isn't a backdoor. If an attacker has such access, you're already screwed. The so-called dev/test 'backdoor' really isn't a backdoor. It's a 'unlock' tool that's required for anyo…

> A backdoor that requires physical access isn't a backdoor. If an attacker has such access, you're already screwed

so why did the original "load an unsigned debug build" functionality require cryptography rather than just, say, holding down the volume button during boot? Because it's not nearly as simple as "I have the hardware, I can do anything".

Re: Microsoft proves backdoor keys are a bad idea

#60

Post by r00fus »

qbrass wrote: post #58
IBM wrote: post #43

Earlier quoted context omitted.

>If an attacker has physical access to your device, you're already screwed. The FBI had physical access to the San Bernardino iPhone. If this were true, what was the point of the public fight with Apple and eventual purchase of a zero day exploit to get into it?

The statement assumes the attacker knows what they're doing when they have access to the phone. To be fair, the FBI did get into the phone, and could have much sooner had they not wasted their time fighting Apple.

They got into an iPhone5C. If that phone was a 5S (and the FBI screwed up the MDM process just like they did) they would be out of luck.
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