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Microsoft proves backdoor keys are a bad idea

theregister.co.uk

11–20 of 106 posts

Re: Microsoft proves backdoor keys are a bad idea

#11
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…

MS' own advisory says you don't need physical access (only admin rights).

Re: Microsoft proves backdoor keys are a bad idea

#12
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…

Don't the keys normally prevent "people with physical access to the device" from easily updating the firmware?

This includes everyone from J. Random Hacker who wants to install on thier own hardware a linux (which might or might not be a good build), and an attacker who has borrowed your device from a hotel room to put some rootkit on it.

Re: Microsoft proves backdoor keys are a bad idea

#13
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…

I think the basic idea is that with physical access in general, the attacker may have an N% chance of accessing it. The adage about physical access isn't to guarantee they will get access, just that you must consider it as such and react appropriately. The adage isn't a declaration of the state of the machine, it's a declaration on how to respond to its loss.

With a backdoor via any means, the attackers now basically have (N+1)% chance of getting that access, and arguably it's much more than a single increment since whereas other exploits "might" exist, these ones will guaranteed exist.

The suggestion and complaint isn't that "no secure boot is better than one that's easily bypassed", the complaint is requiring such a bypass and not giving the actual owners of the machine control over setting up that secure boot. With the RT devices, the user has absolutely no say in the secure boot process, and they're entirely dependent on Microsoft or whatever organization to provide best security practices.

Also, If the user sets up their own key and does it wrong, they have only themselves to blame. If a company or government does it, the user has no one to blame, since often legal contracts prevent any reparations as result of damage done by stuff like this. The US Government, for reasons of varying validity, needs to give you permission to sue it, meaning they can eschew any complaints should they lose the key.

All in all, a mandated backdoor just increases the chance that there will be a violation, takes control away from the user, and provides no compensation if the forced backdoor results in damages to the user.

Re: Microsoft proves backdoor keys are a bad idea

#14
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…

For Windows Mobile RDU, it isn't flashing firmware even :) It's a package to be flashed via iutool. For RT, the official unlocking way is on http://woaunlock on the MS corporate network.

Re: Microsoft proves backdoor keys are a bad idea

#15
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…

> Isn't a secure boot policy that can be bypassed with physical access more secure than none? Of course it isn't. Impossibility of bypassing is the only reason for secure boot technologies to exist. They are invented so that you are NOT automatically screwed if an attacker has physical access to your device. Secure boot technology is fine in principle, it's just stupid position the manufacturers hold. They ignore rec…

>> Isn't a secure boot policy that can be bypassed with physical access more secure than none? >Of course it isn't.

Really?

Suppose that you are choosing a new device. You can choose one that let's a remote hacker install a rootkit via a malicious website, or you can choose one that let's a hacker install a rootkit only when they have physical access to your device.

Which one do you choose, and why is it the latter?

Re: Microsoft proves backdoor keys are a bad idea

#16
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…

> Isn't a secure boot policy that can be bypassed with physical access more secure than none? Of course it isn't. Impossibility of bypassing is the only reason for secure boot technologies to exist. They are invented so that you are NOT automatically screwed if an attacker has physical access to your device. Secure boot technology is fine in principle, it's just stupid position the manufacturers hold. They ignore rec…

You need admin rights, but not physical access.

Re: Microsoft proves backdoor keys are a bad idea

#17
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.

Tell that to the FBI. They seem to have been quite upset about not being able to unlock some iPhones.

Doesn't anyone wonder why you never seem to hear stories about FBI being unable to unlock encrypted user devices? Surely at the number of people who encrypt their Windows devices is in the tens of millions in the U.S. alone, and some of them must have been caught by law enforcement for various crimes.

Re: Microsoft proves backdoor keys are a bad idea

#18

Earlier quoted context omitted.

> Isn't a secure boot policy that can be bypassed with physical access more secure than none? Of course it isn't. Impossibility of bypassing is the only reason for secure boot technologies to exist. They are invented so that you are NOT automatically screwed if an attacker has physical access to your device. Secure boot technology is fine in principle, it's just stupid position the manufacturers hold. They ignore rec…

>> Isn't a secure boot policy that can be bypassed with physical access more secure than none? >Of course it isn't. Really? Suppose that you are choosing a new device. You can choose one that let's a remote hacker install a rootkit via a malicious website, or you can choose one that let's a hacker install a rootkit only when they have physical access to your device. Which one do you choose, and why is it the latter?

What about the third option, where a hacker can't install a rootkit even if they have physical access? That's what MS tried to build, but is now completely broken.

Re: Microsoft proves backdoor keys are a bad idea

#19

Earlier quoted context omitted.

> Isn't a secure boot policy that can be bypassed with physical access more secure than none? Of course it isn't. Impossibility of bypassing is the only reason for secure boot technologies to exist. They are invented so that you are NOT automatically screwed if an attacker has physical access to your device. Secure boot technology is fine in principle, it's just stupid position the manufacturers hold. They ignore rec…

>> Isn't a secure boot policy that can be bypassed with physical access more secure than none? >Of course it isn't. Really? Suppose that you are choosing a new device. You can choose one that let's a remote hacker install a rootkit via a malicious website, or you can choose one that let's a hacker install a rootkit only when they have physical access to your device. Which one do you choose, and why is it the latter?

[deleted]

Re: Microsoft proves backdoor keys are a bad idea

#20
post #6

The researchers' writeup, in a very fun form, can be found at https://rol.im/securegoldenkeyboot/ With text as follows for those whom the joviality of the original presentation is undesirable: irc.rol.im #rtchurch :: https://rol.im/chat/rtchurch Specific Secure Boot policies, when provisioned, allow for testsigning to be enabled, on any BCD object, including {bootmgr}. This also removes the NT loader options blacklis…

We should just swap the top-link to this post, thanks for the detailed write-up!
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