Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

blog.ptsecurity.com

Post reply on HN
Print view View original

11–20 of 85 posts

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#11

Post by userbinator »

bcaa7f3a8bbc wrote: post #3

Does ME Manufacturing mode allow the user to change all the configuration? Does it mean that hackers who incidentally purchased such a machine (but probably not Apple's) with ME Manufacturing mode enabled, can theoretically port coreboot to the machine, then flash their own public key fingerprints into ME, using Boot Guard to protect firmware signed by themselves instead of OEM's? I remember several bunches of Lenovo…

In other words, this vulnerability is "the insecurity that gives us freedom"? That's what it looks like from a quick scan through the article, and if that's the case this is yet another sad instance where the authoritarian "security" community is openly hostile against user freedom.

On that moral point, a relevant comment I made on an article recently: https://news.ycombinator.com/item?id=18102434 Anyone who is actively finding and closing local-only "exploits" for ME, ones which require root access in the first place, is being actively user-hostile.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#12

Post by oneplane »

bcaa7f3a8bbc wrote: post #3

Does ME Manufacturing mode allow the user to change all the configuration? Does it mean that hackers who incidentally purchased such a machine (but probably not Apple's) with ME Manufacturing mode enabled, can theoretically port coreboot to the machine, then flash their own public key fingerprints into ME, using Boot Guard to protect firmware signed by themselves instead of OEM's? I remember several bunches of Lenovo…

You can only flash coreboot if the BootGuard isn't blown. Nothing else will allow you to run coreboot on a mobile Intel platform because the CPU has a hard-fused hash of the public key for the IBB (boot code in the CPU ROM/factory microcode) and via that, the ACM. (Authenticated Code Module, loaded via ME)

This means that you cannot run an Intel CPU without getting an ACM signed by Intel. And that ACM only works with the ME and an Intel formatted SPI flash partitioning scheme.

Keep in mind that this hard lockdown only applies to those SoC-ish chips like the mobile PCH+CPU combo chips. Once the PCH and CPU are separate, it's a different story with real options, all the way down to replacing the PCH with one that doesn't have the fuses for BootGuard blown.

Manufacturing mode does allow you to access all of the SPI, but it doesn't allow you to add malware of change the firmware as long as BootGuard is still on since you need the RSA private key from the manufacturer to change the firmware, or the RSA private key from Intel to change the IBB+ACM combo package.

The Lenovo series you are referring to had a similar but different issue; BootGuard was in validate-only mode, so you can edit the SPI flash and remove the UEFI part, but leave in everything else (ME, GbE, config, IFF, partition data etc.) This has been a non-default configuration for a while, and as you noted, even then it was hard to find one that had that specific firmware/fuse combination.

The ME on platforms with sockets is in the PCH which is on the mainboard, not on the CPU, so in theory it is possible to man-in-the-middle the CPU-PCH communication.

Another note: a lot of Intel boards have the CCA debug options for ME still enabled due to a mishap from Intel; CCA is the Closed Chassis Adapter which basically runs JTAG over USB3 directly onto the ME CPU core. Getting a USB 3 cable and removing some pins turns it in to a poor man's CCA cable, running some FOSS software on the host will then enable to you stop the ME core on the target and modify memory at will. This basially enables a tethered ME jailbreak, but also ME malware persistence.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#13

Post by oneplane »

This is bad in a DoS-type of way. BootGuard only loads correctly signed firmware, the root of trust is an Intel RSA keypair and the hash of the pubkey is burned into the CPU during Intel's manufacturing. The PCH (on the same chip in mobile cases) has the ME which also has fuses, and as long as the CPU only accepts signed code form the ME, and the ME has BootGuard fuse blown, the only thing you can really do is disable a system by nuking the SPI (or just flipping one random bit to invalidate the signature).

To fix it, you'd have to re-flash the SPI chip.

As far as I know, manufacturing mode only allows you to add signing keys if those keys are signed by Intel, so adding your own keys won't help. Adding a key from another manufacturer with known exploitable firmware could work, but loading that firmware on incompatible hardware won't let you boot the machine so you still get nothing.

All in all; nice find, yes you can disable machines via software, but other than that, not as interesting as I had hoped it to be. (IBB or ACM exploits would be very very very sweet)

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#14

Post by drb91 »

Reelin wrote: post #7
bcaa7f3a8bbc wrote: post #3

Does ME Manufacturing mode allow the user to change all the configuration? Does it mean that hackers who incidentally purchased such a machine (but probably not Apple's) with ME Manufacturing mode enabled, can theoretically port coreboot to the machine, then flash their own public key fingerprints into ME, using Boot Guard to protect firmware signed by themselves instead of OEM's? I remember several bunches of Lenovo…

It sure would be nice if we could just purchase such unlocked devices directly. You used to actually control the devices you purchased. Then mobile comes along and so far we've seen locked OS accounts (rooting), locked bootloaders, and locked basebands. Now there's locked ME or PSP. This is getting ridiculous, as well as difficult to keep track of. Perhaps we need some sort of "Fully Unlocked" certification to indica…

> Perhaps we need some sort of "Fully Unlocked" certification to indicate that a device you're considering purchasing would actually be yours?

Maybe we should make it impossible to advertise a product as being purchasable if you also aren't purchasing rights to the software (and the ability to modify it). Just remove ownership from the equation entirely unless they can demonstrate that the user has full control of the hardware.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#15

Post by MisterTea »

turblety wrote: post #5
bcaa7f3a8bbc wrote: post #3

Does ME Manufacturing mode allow the user to change all the configuration? Does it mean that hackers who incidentally purchased such a machine (but probably not Apple's) with ME Manufacturing mode enabled, can theoretically port coreboot to the machine, then flash their own public key fingerprints into ME, using Boot Guard to protect firmware signed by themselves instead of OEM's? I remember several bunches of Lenovo…

Exactly. Remember Intel ME is a great utility and has some awesome abilities. The issue that people have is not the fact there is a CPU running another CPU that looks after the main one. It's that it's closed source and has remote control capabilities that can not be controlled by the user. If Intel would just allow an owner to build and flash their own Intel ME version using their own private/public keys then no one…

> It's the fact it's a secret closed system that has full control to monitor everything you do, and can not be fully disabled.

To add to that, it also makes code audits impossible.

Intel, AMD, ARM, et al: There is zero, and I mean ZERO reason to hide management functionality from users in this day and age. It's 2018, security through obscurity has been proven wrong time and time again. It's foolish to think otherwise. Edit: grammar.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#16

Post by Reelin »

KAMSPioneer wrote: post #10
kazagistar wrote: post #8

Earlier quoted context omitted.

That would only be a useful certification if anything was certified with it.

I can't tell if you and GP are being tongue-in-cheek about FSF's RYF certification or not. Either way, you got a sad laugh from me.

A very depressed sort of tongue-in-cheek, but I sometimes forget that there's no tone of voice on the internet.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#17

Post by [deleted] »

debt wrote: post #6

"The weakness of "security through obscurity" is so well known as to be obvious. Yet major hardware manufacturers, citing the need to protect intellectual property, often require a non-disclosure agreement (NDA) before allowing access to technical documentation. " I believe the actual reason for "security through obscurity" is that it's a delay tactic used against well-funded adversaries. There's an inherent problem…

[deleted]

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#18

Post by tlb »

debt wrote: post #6

"The weakness of "security through obscurity" is so well known as to be obvious. Yet major hardware manufacturers, citing the need to protect intellectual property, often require a non-disclosure agreement (NDA) before allowing access to technical documentation. " I believe the actual reason for "security through obscurity" is that it's a delay tactic used against well-funded adversaries. There's an inherent problem…

It's also possible to build systems that are correct, such that no adversary with any amount of resources could find a security hole. Many CPUs in the past have been correct. Probably most major commercial ones before 2000 were. So it's not mathematically impossible.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#19

Post by jarfil »

userbinator wrote: post #11
bcaa7f3a8bbc wrote: post #3

Does ME Manufacturing mode allow the user to change all the configuration? Does it mean that hackers who incidentally purchased such a machine (but probably not Apple's) with ME Manufacturing mode enabled, can theoretically port coreboot to the machine, then flash their own public key fingerprints into ME, using Boot Guard to protect firmware signed by themselves instead of OEM's? I remember several bunches of Lenovo…

In other words, this vulnerability is "the insecurity that gives us freedom"? That's what it looks like from a quick scan through the article, and if that's the case this is yet another sad instance where the authoritarian "security" community is openly hostile against user freedom. On that moral point, a relevant comment I made on an article recently: https://news.ycombinator.com/item?id=18102434 Anyone who is activ…

"Freedom or persistent compromise" depending on whether it's the rightful owner or an attacker using the exploit. The most user-hostile part is forcing users to choose between accepting an OEM locked down platform, or running an open platform that an attacker can permanently lock down.

Re: Intel ME Manufacturing Mode: obscured dangers and MacBook vulnerability

#20

Post by jarfil »

oneplane wrote: post #13

This is bad in a DoS-type of way. BootGuard only loads correctly signed firmware, the root of trust is an Intel RSA keypair and the hash of the pubkey is burned into the CPU during Intel's manufacturing. The PCH (on the same chip in mobile cases) has the ME which also has fuses, and as long as the CPU only accepts signed code form the ME, and the ME has BootGuard fuse blown, the only thing you can really do is disabl…

It also means that instead of having to compromise Intel's signing key to gain full control, now it's also possible to use any compromised key that's been signed by Intel, which may not be as well guarded as Intel's one.
Post reply on HN