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Comment by alexb_ | Hacker News Reader

A lot of their claims sound very scary but I don't really know what to make of this as an average user. Is there an explanation to what this stuff means for me? What security vulnerabilities does this allow for on Intel CPUs? Are they worth worrying about? On a scale of "minor bug" to "every single intel chip is easily able to run arbitrary code and is vulnerable on a hardware level" how bad is this exactly?

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The instructions they found are only usable when in a special unlocked debug mode that they managed to access through exploiting the Intel CSME at a very early boot stage. Part of the reason this is about ATOM is that they haven't unlocked it yet on other, more recent desktop processors.

So no immediate reason to worry but all the more reason to ask Intel to get all it's fucking "management engine" crap out of processors. There is no reason for this mode to be in production processors at all, or not behind a hard blown fuse.

Every time i read this 'intel managment engine issue' i am like 'oh, it's that time of the year again'

Chipmakers are doubling down on coprocessors with Pluton, first to market in Amd Ryzen 6x series chips. It's a rootkit on your machine plain and simple.

Depending on your security needs, you can go back to transistors à la Ben Eater. Or an Arduino, or a permanently-offline device with its Wi-Fi card unplugged and its Ethernet cable desoldered or poured-in with hot glue/plastic.

Also desolder/unplug the speakers/microphone while you're at it; there may be some air gap leaks that way. Ideally, only use it on a separate power supply also (say, an older vehicle without networking capabilities, or a solar panel).

Check out the Glacier protocol for inspiration: https://glacierprotocol.org/docs/overview/

Just curious. Recently I have picked up the hobby of reverse engineering and I read that some electronics components such as a ROM can be protected by blowing the fuse after writing to it. Is there a physical, affordable way (under 5K USD let's say) to reconnect the fuse somehow?

The cheapest way to reprogram a blown efuse is to buy a new efuse. In some cases, the efuse is a separated chip but it can be integrated into the CPU or Microcontroller, in which case your only option is to find one of those without the efuse blown.

The fuse generally is basically the size of a normal transistor on the IC, good luck getting that repaired otherwise :)

> The cheapest way to reprogram a blown efuse is to buy a new efuse.

I think this somewhat undersells what a monumental task un-blowing an e-fuse on a chip would be (e.g. resetting something like the USB boot enable bit on the RaspberryPi's SoC). If it's even feasible with today's technology, it would take a top-class semiconductor research facility and significant effort to pull it off. It's $millions compared to taking a new ~$1 chip off the shelf.

The fuse generally is basically the size of a normal transistor on the IC, good luck getting that repaired otherwise

https://en.wikipedia.org/wiki/Focused_ion_beam

I'm not sure what resolution they've achieved now, but it's definitely possible to either cut or repair connections using such a machine. It's a very expensive process, but definitely within the capabilities of even the far-East "MCU break" companies.

No, that is usually not possible. Sometines you can reset write-once-bits by shining UV light in the right part of the processor die, or you can try to circunvent the fuse checks by fault injection during, https://media.ccc.de/search/?q=fault+injection

Reconnecting the fuse isn't a thing, as the other comment notes it's just a bunch of atoms somewhere in the chip. But in case of ROM protection for microcontrollers the fuse doesn't directly, in silicon, prevent reading the ROM - after all the controller still needs to be able to read its code! So in practice the fuse only disables e.g. JTAG access, and often that isn't even done in silicon but through a manufacturer boot ROM that checks the fuse state, then either disables or enables JTAG.

So often the easiest way to still read the ROM is to find some vulnerability in the code the chip is running and use that to run some code that can leak the ROM contents. Beyond that it's possible with voltage glitching and similar fault injection methods to get the chip to skip the fuse check or put it in some other indeterminate state that allows access - there are some well documented methods for popular microcontrollers:

https://www.aisec.fraunhofer.de/en/FirmwareProtection.html

> "every single intel chip is easily able to run arbitrary code and is vulnerable on a hardware level"

It's not just Intel though. Both AMD and Apple also have their own "security processor" running its own operating system without your consent in your own hardware. Essentially this means they own the hardware, not us. I don't know if you would call it that, but to me it sure looks like the definition of a universal backdoor.

Or, and here is a crazy idea, maybe they use a dedicated security chip to improve isolation and achieve better security?

Don't know about apple, but the AMD security firmware has been reverse engineered and no backdoors have so far been found.

https://github.com/PSPReverse/PSPTool

Yes, but then you can probe the pins and MITM, like you can with an external TPM chip. (See something like the TPM Genie) It's internal because it's more secure that way.

These are internal soc components, for this very reason.

Not sure if we are agreeing or not...

I read 'dedicated security chip' as something akin to an external chip like a TPM chip as opposed to dedicated transistors in the CPU die (which is more secure). So it sounds like we're agreeing.

The Intel source code was basically leaked for a bunch of their firmware and nothing particularly interesting got out.

Any links? Interested to read more about it.

It did the rounds on here when it happened

Sure, but those of us paranoid about ME can't help but wonder if that was savvy PR.

Security from whom?

Good to see people starting to ask the right questions; (see Snowden: "Permanent Record", Farnell: "Digital Vegan", Anderson: "Security Engineering") - Security for who? Security from whom? Security to what end? There is no such thing as "bare security". No tide that raises all ships. "Security" is now a constant sum game. Your security is my insecurity.

> maybe they use a dedicated security chip to improve isolation and achieve better security?

I call bullshit on this one. Security through obscurity is not a feature. If you want to have a dedicated security chip protecting the users, we need to have all schematics and source code to ensure it's safe and adapt it to specific use-cases.

Ideally, that security processor would be physically separate from the usual hardware and operating on specific data lanes. Just like secure smartphone designs don't give the modem hardware access to all phone memory. That the "security chip" is bundled with the CPU/chipset and answers to undocumented (secret?) x86 instructions means to my understanding that it's impossible (unless you're reverse-engineering the computer at the hardware level) to understand/restrict whatever it's doing.

I mean i find it funny that many of us are running Minix without even knowing it, making it one of the most popular OS on the planet. And i'm glad some security researchers figured out how to disable Intel ME completely via some undocumented instructions. But i would certainly feel safer and more in control if i could know/inspect wtf hardware is doing inside my machine. I would certainly trust a free-hardware CPU without a security chip more than a modern Intel/AMD CPU any day of the week.

Some previous related discussions on undocumented hardware:

- https://news.ycombinator.com/item?id=28977175 OK Lenovo: we need to talk (october 2021)

- https://news.ycombinator.com/item?id=28374523 It's time for Operating Systems to Rediscover hardware Usenix keynote (august 2021)

I think you may be confused about what "security through obscurity" means. The security from these coprocessors is not from obscurity but is part of the design.

I like that we can disable Intel ME entirely via undocumented instructions. The fact that whether it's running at all and whatever computation is running depends on hiding certain x86 instructions and the code/memory of the security module is what i refer to "security by obscurity".

If everything is taken into the design, great! Just open up the design and let us check. Also, if we can't change/upgrade the firmware without cooperation from Intel and motherboard manufacturers, how are we supposed to operate such hardware after Intel/others claims EOL? Or after those corporations die?

I'm not exactly a fan of hardware tokens like Yubikeys but at the very least the design is clear/open. You know the protocol and can probe things around. Those things i don't call security by obscurity (unless your threat model involves someone doing electronics RE on your key). And if a flaw is found with the design, "just" get a new key no need to throw away your entire motherboard. (I still find environmental waste to be a major problem with hardware tokens but that's a discussion for another day)

>many of us are running Minix without even knowing it

This is news to me; any more info?

Basically every modern Intel chip has Intel ME (https://en.wikipedia.org/wiki/Intel_Management_Engine) and that core runs Minix (https://www.bleepingcomputer.com/news/hardware/intels-secret...)

Yes to AMD, not to Apple. There is no secret core on Apple chips that has control over the system. They are much better designed than AMD/Intel CPUs and strictly isolate all secondary cores behind IOMMUs.

By "security processor" you probably mean the SEP (which is one of many secondary cores running Apple firmware). The SEP isn't even running when the OS boots and you can just leave it dead and choose not to use it. Other side cores are running or required to get a functional system, but none of them have unfettered access to system memory or the main CPUs (nor does the SEP even if you choose to use it).

In addition, since Apple splits up coprocessor duties among many cores, that also makes it harder for one to compromise others, or for several to collude to compromise the parts of the system they do have access to. E.g. the coprocessor in charge of the display controller can't go and read your keystrokes or send a capture of the screen to the internet, because it doesn't have access to that hardware.

>There is no secret core on Apple chips that has control over the system.

And this has been documented/proven by whom?

This is based on having spent a year reverse engineering the platform to port Linux to it.

Granted, Apple could've added a hidden secret core with secret firmware we haven't found anywhere, somehow. Of course, so could every other manufacturer. If you are concerned about all potential secret backdoors, you'll have to invest in a chip fab and make your own chips; there is no way to prove that the chip you have in your hands is not uniquely backdoored, no matter what documentation you have or not. Documentation cannot prove that the physical chip matches what was documented.

What I can say is they've done a really good job keeping tight security boundaries in their chips, much better than basically every other manufacturer, by all appearances. What I meant by "secret" in my previous comment was a difficult to observe core with full system access running proprietary code, a la ME or PSP; not literally something that is deliberately hidden so as to be completely undiscoverable. So far, there is no evidence of Apple having added any questionable hardware to these chips.

> How bad is this exactly?

7.1 out of 10

https://www.intel.com/content/www/us/en/security-center/advi...

This was part of IPU 2021.2 in November and other bugs in other CPUs were fixed as well, one rated 8.2 affecting many, but not all, intel cpus (intel-sa-00562). If you haven't updated your UEFI/BIOS since last November and you love to run untrusted code by untrusted third parties on your CPU, the larger story about microcode bugs and privilege escalation into the management engine is bad and best fixed keeping up to date with microcode updates.

Please note that the IPU 2021.2 fixes are not runtime loadable: https://github.com/intel/Intel-Linux-Processor-Microcode-Dat... and require an UEFI/BIOS update.

The concrete story is mostly about a problem with the Atom line, which allowed code execution in the IME and a full dump of it. Very interesting for nerds that want to hack into that for reasons of taking ownership of what they bought, less interesting for malware, but not irrelevant. The link is about the Chip Red Pill Team giving a talk about how they broke the Atom and what intel hides inside.

It is a good talk by people who have years of experience cracking open Intels chips. I can recommend it to anyone who cares about that.

From a news perspective however it is three month old, if we ignore the zero nights russia talk in September ;-)

> every single intel chip is easily able to run arbitrary code and is vulnerable on a hardware level

Isn't this what we want?

What's the alternative? Your CPU can't run arbitrary code? Having hardware access doesn't give you complete control of the hardware?

I mean you're being nitpicky with my words here. I'm obviously talking about malicious actors when I use the words "vulnerable".

When we are living in an era of "war on general-purpose computing", where lots of people in the industry work very hard on taking away our freedoms, it is very important to be precise.

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