7 ms·
The followup tweet indicates that the CPU has to be in an unlocked state before this is possible, which on a typical system requires there to be a Management En
by mjg59 6y ago
The followup tweet indicates that the CPU has to be in an unlocked state before this is possible, which on a typical system requires there to be a Management Engine vulnerability first. Given what we currently know, this is going to be interesting for people interested in researching the behaviour and security of Intel CPUs and might well lead to discovery of security issues in future, but in itself I don't think this is dangerous.
Edit to add: https://www.intel.com/content/dam/www/public/us/en/security-advisory/documents/the-intel-csme-dam-vulnerability-cve-2018-3659-and-cve-2018-3643-whitepaper.pdf https://www.intel.com/content/dam/www/public/us/en/security-... is a discussion of a previous Intel security issue which includes a description (on page 6) of the different unlock levels. This apparently requires that the CPU be in the Red unlock state, which (in the absence of ME vulnerabilities) should only be accessible by Intel.
- deleted 6y ago[deleted]
- xwolfi 6y agoSo you mean, if I am a state actor able to kidnap the child of an Intel high level employee... say I m Joe Biden, I can ask Intel to... remote unlock my CPU and read arbitrary memory block ? Or you mean Intel had to physically handle your CPU with a debug cable or whatever ? Cause I really dont feel it s okay that the only safety we have from a newly discovered exploit is that there needs to be another newly discovered exploit :D
- tedunangst 6y agoDon't use CPUs from companies that have employees that can be kidnapped.
- thayne 6y agoDon't use CPUs from companies that have employees.
- fctorial 6y agoDon't use CPUs from companies.
- sodality2 6y agoDon't use anything
- mightyoj 6y agoDon’t
- sgtnoodle 6y agoDon't be so paranoid. Just build your own CPU from discrete NAND gates like everyone else.
- tartoran 6y agoA pen and paper is everything you need.
- colejohnson66 6y agoBut what if it’s some of that fancy paper or a pen that records everything you write! Might need to manufacture your own pen and paper now...
- smlss_sftwr 6y agoHold up there you don't know if someone's been tampering with the trees, you'll have to grow your own forest first
- cwillu 6y agoThe “trusting trust” flaw still applies, better sequence your own species of tree.
- justinclift 6y agoDoesn't seem like that would leave many possibilities... ;)
- fulafel 6y agoI guess out of business CPU companies are one easily accessible category.
- justinclift 6y agoWhile true, it's pretty likely their IP was sold to still-in-business companies. ;)
- mjg59 6y agoRemotely? I think Intel would need to produce a backdoored ME firmware, get the system vendor to incorporate that into a system update and then convince the target to flash that. In that sense I don't know that they'd technically need physical access, but it doesn't really meet most people's description of a remote attack.
- scaramanga 6y agoIt is public knowledge that US intelligence agencies actually just hijack computers and equipment on their way to the customer and install hardware backdoors there (Snowden et al., 2014). It is also known that they have had backdoors in commercial systems as they came off the shelf, but I think usually those were CIA owned and controlled companies like the crypto AG phones. What is unknown (pure speculation) is whether, for example, Intel CPUs come backdoored straight from the factory floor? On the one hand, that would be a powerful capability to have, but on the other hand, the risk of exposure and subsequent damage to the US economy, prestige, etc. would be non-zero. So it's hard (for a plebian like me, anyway) to estimate how those costs/benefits might be weighed up by the US government.
- boomboomsubban 6y ago>What is unknown (pure speculation) is whether, for example, Intel CPUs come backdoored straight from the factory floor? There is also a third possibility, that some intelligence agency invested a ton of cash into finding abusable exploits in these systems giving them the same access a backdoor would provide. Also from the Snowden leaks, we know that they have programs with budgets in the millions into finding similar exploits and that there were similar programs outside Snowden's clearance. And though a bug may cause the same damage to the economy, it wouldn't hurt US prestige in the same way.
- jeffbee 6y agoBudgets in the millions, eh? So two full-time engineers?
- boomboomsubban 6y agoSorry, I misremembered the details. Around $400 million a year for the one program we have details on.
- rblatz 6y agoIf I'm the CIA I have dozens of highly placed agents or at least informants at Intel. Not necessarily placing backdoors, but finding and not fixing exploits and sending them back to the CIA for later use. It would be extremely cheap, hell if I'm China, Russia, the UK, or Israel I'm doing the same thing.
- strstr 6y agoThis seems like yet another thing on the list of “x86 hardware issues that sound worse than they are”. I’m interested to see what people are able to reverse engineer with these sorts of tools. It wasn’t even that long ago that ucode wasn’t even encrypted with integrity. I don’t think AMD started doing that until around 2010. I’m also curious which hardware versions this works on, since it’s not obvious it’s universal. I’ll be amused if it’s some forlorn low power chip from 10 years ago.
- gruez 6y ago>It wasn’t even that long ago that ucode wasn’t even encrypted with integrity whether they're encrypted or not doesn't really matter. what actually matters is whether they're signed or not. There was a talk given in 2017 about trying to modify the microcode in AMD processors, but they were using processors from a decade ago (AMD K10, introduced 2007). That makes me think that processors made in the past decade are probably using signed microcode.
- deleted 6y ago[deleted]
- colejohnson66 6y agoIs it this one? https://www.usenix.org/system/files/conference/usenixsecurity17/sec17-koppe.pdf https://www.usenix.org/system/files/conference/usenixsecurit...
- gruez 6y agoYeah, although I didn't find the original paper. Reading into it more, they mention when AMD and Intel started signing their microcode. >Note that Intel started to cryptographically sign microcode updates in 1995 [15] and AMD started to de-ploy strong cryptographic protection in 2011 [15].
- dooglius 6y agoThis would still break SGX/remote attestation, no? The chip can correctly say it's running some piece of assembly but if "ret" has been redefined to do whatever I want...
- userbinator 6y agoThat would be a good thing, given what those features are usually used for (DRM and other user-hostility).
- deleted 6y ago[deleted]
- sodality2 6y agoThis is what I'm interested in since they pushed that so heavily.
- strstr 6y agoThe keys are stripped out if you put it into the required unlock mode.
- tkinom 6y agoI would love ability to redefine call/ret to profile an app without compiler generate diff code.
- vlovich123 6y agoCan’t you do that through ebpf?
- tkinom 6y agoMy understand of ebpf can hook into the function calls in linux kernel. Can one do that on user space app?
- 6y ago
- runjake 6y agoPlot twist: there’s been a few ME vulnerabilities. And who knows what other purposeful ME backdoors there may or may not be.
- mjg59 6y agoSure, which is why this is useful to researchers. But the access someone needs to your system in order to exploit the ME vulnerabilities is sufficiently extreme that if someone achieves it you probably have other things to worry about.
- m3kw9 6y agoOr the only thing to worry about
- spacemanmatt 6y agoI can't get with justifying one serious security problem using another. Attackers increasingly combine local privilege escalations to move laterally, but only need one RCE to get in.
- mjg59 6y agoWindows can be booted into test keys mode, which allows the loading of unsigned drivers. We don't consider that a security issue because the privileges you need in order to switch to that mode are equivalent to the privileges you get by switching to that mode. It's the same here - the ME is the root of trust on Intel platforms. If you're in a position to execute arbitrary code on the ME then you've already got the ability to compromise the rest of the system enough to run arbitrary code on the host CPU, and being able to modify microarchitectural state doesn't give you additional privileges.
- vlovich123 6y agoI’m not saying that’s the case here, but that’s the general problem with the line of reasoning that “hey if you already have permission X then doing Y is the least of your concerns”. The concept of defense in depth literally relies on each barrier being independent and robust. That’s why you see hardening of Linux’s hibernate even though the common refrain is “well if you have physical access the game is lost”. There are things that even root can’t do even though “hey if you have root the game is lost”. The point of the game is to never lose even in very adverse environments.