OpenBSD Chief De Raadt Says No Easy Fix For New Intel CPU Bug 'TLBleed' (itwire.com)

Recompiling is unlikely to be a catch-all solution for a recently unveiled Intel CPU vulnerability known as TLBleed, the details of which were leaked on Friday, the head of the OpenBSD project Theo de Raadt says. iTWire reports: The details of TLBleed, which gets its name from the fact that the flaw targets the translation lookaside buffer, a CPU cache, were leaked to the British tech site, The Register; the side-channel vulnerability can be theoretically exploited to extract encryption keys and private information from programs. Former NSA hacker Jake Williams said on Twitter that a fix would probably need changes to the core operating system and were likely to involve "a ton of work to mitigate (mostly app recompile)." But de Raadt was not so sanguine. "There are people saying you can change the kernel's process scheduler," he told iTWire on Monday. "(It's) not so easy."

He said that Williams was lacking all the details and not thinking it through. "They actually have sufficient detail to think it through: the article says the TLB is shared between hyperthreading CPUs, and it is unsafe to share between two different contexts. Basically you can measure evictions against your own mappings, which indicates the other process is touching memory (you can determine the aliasing factors)." De Raadt said he was still not prepared to say more, saying: "Please wait for the paper [which is due in August]."

Comments

Illusion of speparation in VM

[sinij]

If not this one, maybe the next bug of this kind will finally put illusion of VM separation to rest. If you are running something in the cloud, there is no way to secure it. Start bringing important stuff back in-house, and better use dedicated hardware. Yes, these old-fashioned blade servers were in the access-controlled server room for a reason.

Re:Illusion of speparation in VM

[Anonymous Coward]

If we'd be willing to deal with choppy timeslicing where you give the whole processing (all cores & GPU) away for a longer timeslice and fully scrub cache state between and swap for a whole new RAM bank, you could probably start to think about making some guarantees.

But damn that throws away so much performance and response speed.

Of course the world will settle somewhere between that extreme and the current state (probably much closer to the current state for a while).

Re:Illusion of speparation in VM

[Pseudonym]

Take a cue from the C++ people. VM separation protects you from Murphy, not Machiavelli.

Re:Illusion of speparation in VM

[AmiMoJo]

You have to weigh the possibility of an unpatched cloud server being compromised by a neighbouring VM against the possibility of your own in-house servers being hacked.

Cloud companies so security on a massive scale and all the big guys like Amazon, Microsoft and Google have a track record of keeping their systems up to date and secure. It's no wonder, because they can afford the best security staff and security is a core part of their business.

Your locked server room looks impressive but is reliant on who you can afford to employ to secure it. In fact you really need a team working on security, rather than a single point of failure. And you had better be ready to test and deploy patches fast too.

Also, the VM isolation issue isn't really an issue because you can just pay a bit more to ensure no-one else's VMs are running along side yours. For really secure stuff it's a good idea to encrypt data in RAM too, which AMD supports in hardware to mitigate exactly this kind of attack. Different key for each VM of course.

PCID should help.

[iive]

PCID should help with this kind of vulnerability too.

When mitigating Meltdown, one way was to separate completely the kernel memory from user process memory, this involved switching the virtual paging memory and this flushed TLB entries.
This causes speed decrease. To mitigate this, (some) CPUs have a feature where it writes the process ID into the TLB entry, so it could remain in the cache, but it would remain inactive while another process is running.
While this sound like the perfect solution, the problem is that the ID field is not big enough and should be switched and recycled.

Special settings

[duke_cheetah2003]

Like Meltdown and Spectre, this 'exploit' requires a lot of things to be 'just right' for an exploit or data leak to occur.

I'm not saying they're worthless exploits, but again, when I read some of the particulars about the research.. well this popped out:

The team used AI – specifically, a support vector machine classifier – to identify when a program is executing a sensitive operation, such as a cryptographic function, through the TLB latencies, and read out that app's private data as a stream of bits, allowing them to reconstruct things like crypto keys. There are hurdles to overcome, such as address-space layout randomization – however, the team believes these can be defeated in real-world attacks.

So I really don't know a lot about AI implementations, but I'm going to take a liberty and say, that's probably computationally expensive to be doing. That they needed an AI to even get anywhere examples how sensitive this exploit truly is. Expecting to deploy an AI in the wild (malware) and have it grabbing stuff from whatever... it's a pretty big stretch from these laboratory conditions to real-world.

I'm not going to say there's nothing here, but I am going to say: Where's the beef? Cuz it's awfully small with this exploit, there's much easier ways to steal information.

Lastly, it seems isolated to HyperThreading Intel CPUs, from what I read. Yes, it's a big attack surface, but still.. an exploit working in your special setting doesn't really move me much, especially how special these particular set of conditions were.

Re:Special settings

[93 Escort Wagon]

Theo: Worried
Random Slashdotter: Not so worried

No offense, but I’ll go with the OpenBSD and LibreSSL guy on security matters.

Re:Special settings

[Tough Love]

Like Meltdown and Spectre, this 'exploit' requires a lot of things to be 'just right' for an exploit or data leak to occur.

All computer programs require that. It is amazing just how fast and accurately these Meltdown readers can dump out kernel memory. That is just the ones we know of, there are many better ones in the wild, no doubt.

Re:Special settings

[Ol Olsoc]

Case in point, the amount of utterly #@$%ing stupid security guys who insist on quadruple random pass on hard disks to wipe, /then shredding them physically/.

I always thought that was sort of a "guy thing". I've had fun drilling holes through hard drives, then crushing them in vices. Even took a few to the rifle range. When in fact, I knew that:

In reality there's never been a proven case of restoring data from a hard drive that's been written even just once with 0s.

Pretty much this. Early on, I asked how exactly data could be retrieved from an overwritten drive, and got a strange "edge of the written area" response. Then I asked why the new data wouldn't write to the "edge of the written area". Didn't get an answer.

I'd be comfortable stating on my experience, over 85% of security people I've encountered in the industry to be nothing but a hindrance, who love saying no to things, for the sake of looking important.

That's a bit harsh. There is an old saying that you can't know what you don't know, and it is pretty difficult for any one of us to know every vulnerability out there. So the security guy or gal tends to get pretty cautious in outlook.

Re:Special settings

[DarkOx]

You have to consider the scope though - Both Random Slashdotter's lack of concern and Theo's worry are justified in my opinion.

Theo: is developing an operating system that is supposed to be essentially the most secure choice. He has a user base that will be deploying it on high value targets. High enough value that a state actor or other well funded well connected group might take interest. Such groups would be capable and willing to develop situationally specific malware + exploit code. If I was using BSD/Intel to run my uranium enrichment process - I'd worry.

On the other hand as far as Random Slashdotter goes - He is probably correct that we won't see this as a metasploit module or meterpreter plug-in anytime soon. Its debatable as to if these exploits could be used in the 'wild' without being highly customized for the target by people who have advanced math/comp sci degrees. In other words even if your bitcoin wallet stored on that VPS is worth few hundred thousand its likely impractical to go after you in this way. So being somewhat dismissive about these attacks as an individual is justified as well.

Re: Special settings

[dgatwood]

There's a reason why DoD spec is 7 passes over the disk.

The reason is that it might have been possible, back when track width was much wider and head positioning accuracy was much lower.

I am an old nobody

[oldgraybeard]

but the fact that the vendors put a secret OS with an api within the cpu below the bois/command set? Who thought that was a good idea. And who did not see the problems and issues.
I know, I know nothing, I wrote z80 assembly as an intro. I am missing the entire point of what the wise individuals are doing..

Just my 2 cents ;)

Re:I am an old nobody

[grep -v '.*' *]

I know, I know nothing, I wrote z80 assembly as an intro.

I learned on an MITS Altair-8800 computer that my roommate had in college. We played one dimensional, straight-line Pong, and had to flip the front-panel switches to reload the program after shutting it off. (5.1 Audio? Mouse? CRT? Printer? Floppy? Keyboard? Paper-tape? You must be joking.)

After graduation, I ended up at his computer shop running CDOS, a CP/M improvement from Cromemco with hardware. They eventually upgraded from 8080 to a Z-80. Really neat, with those 2nd set of registers. We wrote COBOL and Fortran accounting software using embeeded software overlays and 8" floppies and 5-10M hard drives. (150K? 5 Meg? Is that right?? We only had 64K of RAM though, MAX) for companies.

Hey, did you ever see that Zilog Z-80 paperback book (6"x8"? Weird size.) describing how all of the operations worked in pseudo-code? It was wonderful.

I still have a Z-80 fold-out instruction card. Also an IBM 360 one, much longer. Not much useful now, but extremely useful at the time.

Also, decades ago now, IBM produced (as an experiment, not a retail product) a mainframe computer-on-a-chip, but supposedly the firmware was changeable to directly run binary code from IBM 360, PDP, Amdahl, and maybe 3 other CPUs. A decade or more later you've got (we had internal Compaq In-Site cards) things which directly control the computer remotely, even when "it's off". I understand the new corporate ones have it all built on the motherboard. Still need power to the PS though, but you could insert floppy images and flash firmware while sitting at your desk. Neat-O!

I used to understand how things worked, down to the bare metal. (Could program PICs and INT handlers and all that. You too, I'm sure. Remember 16550 UART serial chips with 14-byte internal cache? ) I fiddled with AI a bit in college in the late 70s. It was bloomin' math magic then, I could run the simple operations by hand or look at the intermediate data structures. But it was all just random junk -- except it would actually come out with working answers. I can't imagine and don't understand what they're doing now -- and really, I don't actually think they do either.

Re: Intel only

[Bing Tsher E]

My SparcStation IPC is safe. Uses regular old 30 pin DIMM memory, even.

Re:The problem is the douchebag humans

[BlueStrat]

[The problem is the douchebag humans]

who waste their life coming up with ways to fuck up other peoples' day by hacking their computer.

Pondscum basically. Or pathogenic bacteria. Take your pick. But such is life I guess.

There will always be a criminal element in any free and open society. That's really just human nature.

No, the real problem here are governments that insist people not be *too* secure in their data, communications, and with whom they associate (there is no freedom of association if all your associations are tracked, stored, and analyzed).

Strat

Hm

[skovnymfe]

Am I to understand that every single performance enchancement made by Intel in the last 20 (?) years is flawed and prone to disaster-bugs?

Re:Hm

[EndlessNameless]

AMD CPUs have many of the same features---TLBs, speculative execution, hyperthreading---without sharing all of the same vulnerabilities. There is enough overlap to suggest there are some unavoidable risks with performance-enhancing features.

It appears Intel was particularly blind to those risks, but bear in mind that some of those vulnerabilities are present on AMD as well.

Since Intel alone was called out on this, I assume AMD's hyperthreading design is safe---for now. Since both hyperthreading designs show similar performance gains, I'm not sure Intel got a performance boost from this defect at all.

Perhaps they saved a few transistors or were able to clock higher, though, so it's not entirely clear there was no benefit.

Re:Hm

[TheRaven64]

Pretty much all CPU vendors were vulnerable to Spectre. Intel helpfully patented the technique that led to Meltdown, so the only non-Intel chip that was vulnerable was a very recent ARM core (released just after the patent expired, such bad timing!). Some of the more recent vulnerabilities rely on particular microarchitectural choices, so are probably limited to Intel. I suspect that other out-of-order cores will have some similar issues, but Intel is in most machines in all of the big cloud data centres so it's the highest-value target.