Ok, I get it. The message is "don't use backdoors, because they'll inevitably get leaked", which I agree with.

Unfortunately, I don't think that's the message that's being interpreted by the vast majority of readers. I'm delving into opinion territory now, but when the word 'backdoor' is used, aren't most people going to assume that it's an FBI backdoor, instead of a test/development backdoor? This seems like the kind of article that fans the fuels of conspiracy theorists, and no one seems to be doing anything to correct the record.

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 complete access to any computer in the world, then they worry when the Chinese and Russians find them.

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 anyone who's going to engineer the device. My main beef is that this article appears to be re-branding the engineering unlock as a backdoor, and confusion is obviously ensuing.

Again, In my original post, I asked "What's the exploit"? and I understand that the existence of an exploit might not be the article's subject, but If you really think that there's a security problem here, I'll ask it again: "What's the exploit?"

> 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.

> 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".

> 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.

Then why bother trying to lock it down in the first place?

Service providers that wish to provide subsidized devices as part of service contracts usually require that said devices can't be repurposed for the duration of the service contracts. Thus a means is needed to lock a device.

The term "backdoor" derives from the very notion of a door. In the back whatever it is you're trying to secure.

I'm finding your line of argument across multiple comments increasingly disingenuous. You're hurting your argument far more than you're helping.

With all due respect, What argument do you think I'm trying to make?

I ask this because I'm still rather unclear about the argument that the original article is trying to make. I'm even more confused about what conclusions slipstream would have us draw from his web-post. Some comments here say that it's not an exploit, that instead its a lesson about why you shouldn't, as a matter of policy, include backdoors. Others say that it is a backdoor/security hole, and are appropriately up in arms over it. The only thing I'm confessing is confusion.

I understand that you think I'm being disingenuous, and the nice thing is that we really don't need to continue this conversation. If it is as bad as some are suggesting, than wouldn't an exploit be out in the near future? I'd expect such an exploit, or even evidence of a backdoor, to make further news, and if I see it then I'll obviously have my answer.

I'll bite. The original article is from the Register. If you work at Microsoft and read HN I'd expect you have a reasonable idea of their average article quality.

I don't think they were trying to make any particular point rather than generate pageviews with a combination of "haha M$" and righteous anti-backdoor anger.

That said, I myself agree with other commenters that your stance "this isn't a backdoor because it requires physical access; if you've given up physical access you're already screwed" is beyond disingenuous. Disregarding a login screen bypass by the same logic would be rightly pilloried. Yes, physical security is the hardest to improve, but that's exactly the carrot Microsoft has used to try and convince the world Secure Boot isn't a pure anti-consumer move.

> "...your stance "this isn't a backdoor because it requires physical access; if you've given up physical access you're already screwed" is beyond disingenuous. "

Ok, I'm open to the possibility that my views might be dated on this.

But, to be fair:

1) the 'physical access' rule was an absolute given in training that I've taken. (I'll let you draw your own conclusions since that the training was hosted by Microsoft). I guess I've had it drilled into my head for so long that I didn't even think the assertion would be controversial here.

2)Schneier commented on here (https://www.schneier.com/blog/archives/2009/10/evil_maid_att...) stating: "As soon as you give up physical control of your computer, all bets are off."

Granted, Schneier's comment was in 2009, and it's possible that expectations on security have changed since then, but

3) this stackexchange question (http://security.stackexchange.com/questions/19334/what-can-a...) is a bit more recent. Some quotes:

"Physical security is a critical (arguably the most critical) part of IT Security. At the end of the day, almost anything can be overridden with local access to the hardware."

"If a "hacker" with any real experience or skill has physical access to a PC, I would just throw away the hard drive and start fresh."

4) even some other comments in this thread (https://news.ycombinator.com/item?id=12264137) don't paint my notion as disingenuous as you might.

Again, I'm not a security expert, but do you think I could be forgiven for making such an assertion?

Not to split hairs, but there's physical access and there's physical access. I've got a Windows RT device up there in my livingroom, but as much as I can pick it up, heft it at the wall, or poke my pinkie into its USB port, I'm not the kind of dude who can crack it open and steal an encryption key that's being transmitted across a bus on the third layer down of its motherboard. I can, however, log in as administrator, download a CMD script (or whatever), and run it. Which one of those is physical access? I guarantee that if you asked one of those greybeards who told you about physical access, they'd back up to the stealing-a-key-from-a-bus scenario, which is out of bounds of reality for most of us. The exploit at hand is not, and I think that's the difference.

> Again, I'm not a security expert, but do you think I could be forgiven for making such an assertion?

Yeah, I forgive you.

The "backdoor" isn't the package that got leaked, it's the private key that signed the package. Without the key, the deployed packages wouldn't be serviceable in case a real exploit was found. Without a serviceability plan, they couldn't have released Secure Boot. So the question isn't whether there was a back door - there had to be a back door - it's whether Secure Boot is a legitimate thing to have.

Deflecting all possible arrows, comes to mind.

Spaghetti to a wall as well.

You're not arguing coherently, effectively, logically, or using terms defined as they're commonly understood.

It's like saying the admin/root account is a backdoor because it allows you to do anything to the system.

> It's like saying the admin/root account is a backdoor because it allows you to do anything to the system.

It's more like saying having a admin/root account and a post-it with a password hint is a backdoor (which is also wrong, of course).

Installing an OS when Microsoft doesn't want you to is the exploit. The legitimate user is the "attacker," Microsoft (or their policy) is the "target."

(I'm not sure if that's what the Register was trying to say, because they're kind of screechy and incoherent at the best of times, but that's how I personally read it.)

A backdoor is a backdoor = unauthorized access to a user's device. What does it matter if it's Microsoft, FBI, or the Chinese government using it? By definition, it can't be "just Microsoft" anyway, as the people who discovered this pointed out, whether it's up to Microsoft or not.

> and no one seems to be doing anything to correct the record.

Maybe Microsoft feels guilty about it? It reminds me of when a journalist asked them about Bitlocker being backdoored, and they refused to comment.

https://www.schneier.com/blog/archives/2015/03/can_the_nsa_b...

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.

But it's ok if Samsung, Google, Apple or whoever else lock you out of the device? Or at least they're not doing it to protect their monopoly.

Also, we're talking about Microsoft ARM based devices so what monopoly are they trying to protect? The monopoly on landfill space they used to dump all the Windows RT devices they failed to sell?

> But it's ok if Samsung, Google, Apple or whoever else lock you out of the device? Or at least they're not doing it to protect their monopoly.

No, it is not ok. Kindly point me to the place where I said it is ok. (That said, Google sells phones with unlocked boot loaders, and have similar "Developer Mode" support for Chromebooks. Samsung and Apple to the best of my knowledge do not sell unlocked phones but do sell unlocked laptops).

> Also, we're talking about Microsoft ARM based devices so what monopoly are they trying to protect? The monopoly on landfill space they used to dump all the Windows RT devices they failed to sell?

Ah, but they wouldn't have produced millions of these devices if they didn't think they could sell them. The ARM based devices were a test of the waters.

Microsoft requires, on x86, that trust of the MS key be preinstalled and that it be possible to turn off UEFI - but they do not require (e.g.) that there be an ability for the user to remove the MS trust or add new trust. (All of these requirements support their monopoly).

I cannot know, but I suspect Microsoft is playing the long game here, and that at some point after Win7 extended support (4 years from now), they plan to require that UEFI cannot be turned off for a machine to be certified to run Win10 "dominion edition". They've started with restricting kernel drivers in the "anniversary edition". I suspect The ARM UEFI was a test for this.

If I am right, the failure of WindowsRT will not change the course of this long game; hopefully something else will (right now, the emergence of reasonable Chromebooks is the only thing that appears to have the potential to stop it)

> Google sells phones with unlocked boot loaders

They also sell carrier editions with locked boot loaders just like everyone else. Locking boot loaders is usually a carrier requirement imposed on manufacturers, not something OEMs arbitrarily decide to do, unless you're TP-Link.

> have similar "Developer Mode" support for Chromebooks.

CoreBoot on Chromebooks is just as locked down as UEFI Secure Boot if not more so. The RW Firmware isn't loaded unless the RO Firmware permits it and you can't modify or replace the RO Firmware by software. It requires hardware modification. Enabling Developer Mode on a Chromebook is analogous to disabling Secure Boot in UEFI.

> Samsung and Apple to the best of my knowledge do not sell unlocked phones but do sell unlocked laptops).

Samsung UEFI laptops have been known to brick if you try to boot Linux, not fail to boot but BRICK. Apple's laptops are absolutely locked down using EFI, you can't install any other OS unless Bootcamp allows it.

> Microsoft requires, on x86, that trust of the MS key be preinstalled and that it be possible to turn off UEFI

Secure boot is a security feature that validates code prior to execution via PKI in a signature database. The PK, is created and owned by the OEM and it can add KEKs from vendors (or distros) to allow them to sign their code. This database is owned, controlled and populated by the OEM, not Microsoft. Microsoft has no control over it beyond making their software refuse to function on not compliant systems. However the purpose of the feature is the inverse of that. That being said, there are several Linux Distros that support Secure Boot and offer PKIs for vendors.

Starting with Windows 8.1, Microsoft requires that new systems support Secure Boot have it enabled with Microsoft's PKI. That doesn't stop you from disabling it to use another OS. It doesn't inherently lock anyone out using whatever software they want, that decision is made by the vendor. The whole point of the system is to protect users from a compromised system, if someone tampers with Windows or it's drivers then the UEFI will refuse to boot it. It has absolutely nothing to do with locking people out.

Now on their RT/Mobile devices you can't disable UEFI Secure Boot. That's akin to locked ROMs and it's a requirement from Microsoft. There's no expressed reason for this but it's obviously because Microsoft gives OEMs subsidies to make Windows RT/Mobile devices so the hardware is often less expensive than comparable Android hardware. The last thing MS wants is for people to replace Windows on the devices with CyanogenMOD.

> They've started with restricting kernel drivers in the "anniversary edition".

Your implication is that this is a user hostile action when it's really a security measure to prevent naive users from installing hostile drivers. You can disable the feature by turning on developer mode. Now that's ok for Google's Chromebooks but not Windows?

You're attacking Microsoft for things you're giving everyone else a pass on.

> Apple's laptops are absolutely locked down using EFI, you can't install any other OS unless Bootcamp allows it.

Not exactly true, or even a little bit true; however, I'd say that these tools aren't exactly well known.

http://www.rodsbooks.com/refind/

> This page describes rEFInd, my fork of the rEFIt boot manager for computers based on the Extensible Firmware Interface (EFI) and Unified EFI (UEFI). Like rEFIt, rEFInd is a boot manager, meaning that it presents a menu of options to the user when the computer first starts up, as shown below. rEFInd is not a boot loader, which is a program that loads an OS kernel and hands off control to it. (Since version 3.3.0, the Linux kernel has included a built-in boot loader, though, so this distinction is rather artificial these days, at least for Linux.) Many popular boot managers, such as the Grand Unified Bootloader (GRUB), are also boot loaders, which can blur the distinction in many users' minds. All EFI-capable OSes include boot loaders, so this limitation isn't a problem. If you're using Linux, you should be aware that several EFI boot loaders are available, so choosing between them can be a challenge. In fact, the Linux kernel can function as an EFI boot loader for itself, which gives rEFInd characteristics similar to a boot loader for Linux.

You're right, this is 100% not true. I've installed VMWare ESXi on modern Apple hardware using tools like rEFIt. It's actually easier than on an equivalent PC since you never have to deal with the Secure Boot garbage.

I think thereg didn't get that quite right. From reading the original advisory, I would conclude that this is not a backdoor (a by-design security "override"), but an actual vulnerability in the boot loader, where it does not check the type of the signed data blob (policy vs. supplemental policy) and thus can be exploited to disable further signature checks. The effect is the same of course, both to attackers and to device owners.

One could speculate if this is a backdoor created with plausible deniability, maybe paid for by some three letter agency. But the evidence doesn't really point into the direction of an intentional backdoor.