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ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

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Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#241

Post by ct520 »

dfrage wrote: post #209
TomVDB wrote: post #190

Earlier quoted context omitted.

They are not for all kind of attacks. E.g. this new one can only be reproduced on Intel, not on AMD and ARM. If you want to ban speculative execution for everything, you need to make the case that it's a fundamental issue and not an implementation specific issue. Right now, that's not the case for many of these vulnerabilities.

As I understand it, the Intel only vulnerabilities, Foreshadow/L1TF, and this set which I've not looked at the details of yet, are targeting specific Intel features, and there's no reason to believe a similar focus on the other companies' products wouldn't also find unique problems. For example, the first version of Foreshadow went after the SGX enclave. Given how widespread Meltdown and Spectre bugs are, there's abs…

" and there's no reason to believe a similar focus on the other companies' products wouldn't also find unique problems."

Sure there is. Just like the first round last year, intel totally through AMD under the bus to save face and stock price. That is the reason to mention AMD literally, to keep their stock price from crashing.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#242

Post by nwallin »

ccozan wrote: post #102
School-Cotton wrote: post #81

Earlier quoted context omitted.

To give ballpark numbers: modern Intel processors can retire a few instructions per cycle in tight loops (4 is the theoretical maximum; > 2 is realistic in a lot of high-performance code). A branch misprediction wastes 10-15 cycles. So getting rid of speculation entirely, and stalling on every branch, would waste time equivalent to dozens of instructions. On typical code that has a branch every few instructions, this…

Can we actually compute without branching? Genuine question. What architecture would do that, and how?

You can compute with less than that. (all links are to the same thing)

https://github.com/xoreaxeaxeax/movfuscator

https://m.youtube.com/watch?v=R7EEoWg6Ekk

https://news.ycombinator.com/item?id=18991404

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#243

Post by shittyadmin »

userbinator wrote: post #238

An unprivileged attacker with the ability to execute code That sounds like a contradiction --- if you can already execute code, I'd say you're quite privileged. It's unfortunate that their demo doesn't itself run in the browser using JS (I don't know if it's possible), because that's closer to what people might think of as "unprivileged". The attacker has no control over the address from which data is leaked, therefo…

> That sounds like a contradiction --- if you can already execute code, I'd say you're quite privileged.

If you're in a VM, you have no privileges over the host CPU, you can't switch to another VM or to the host itself. That's what's meant by unprivileged here.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#244

Post by ct520 »

bigmattystyles wrote: post #153

Why doesn't this type of news cause INTC to tank - they're up today. I know the market is up today, but (and it's probably my innate overreaction) I would think this sort of news would cause its stock to suffer.

It should take a couple of days, also Intel is coming off continuous losses.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#245

Post by shitloadofbooks »

xondono wrote: post #82
daeken wrote: post #3

Pandora's box was opened with the public disclosure of Spectre and Meltdown. Security researchers will continue to find new and better ways of attacking the security boundaries in processors, and there's unlikely to be an end to this any time soon. Exciting time to be in security, not such an exciting time to be a potential victim.

Security by obscurity is no security

_Please_ stop parroting this line incorrectly.

Security _ONLY_ through obscurity is not security. Obscurity is a perfectly valid layer to add to a system to help improve your overall security.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#246

Post by ct520 »

peterwwillis wrote: post #54
gmueckl wrote: post #14

These CPU flaws make it seem as if virtualization in the data center is becoming really, really dangerous. If these exploits continue to appear, the only way forward would be dedicated machines for each application of each customer. Essentially, this might be killing the cloud by 1000 papercuts because it loses efficiency and cost effectiveness and locally hosted hardware does not necessarily have to have all mitigat…

The point of virtualization isn't to add security. It gives you functionality you just cannot have otherwise, and the cloud enables you to scale in a way that is impossible otherwise. If there are security holes, they get patched and the market moves on. It's not just going to abandon either the cloud or virtualization.

I don't agree with that statement. As a stand-alone physical machine is expected to be secure in its own enclave an I think it's within reason a virtual one would have the same expectations.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#247

Post by kbenson »

userbinator wrote: post #238

An unprivileged attacker with the ability to execute code That sounds like a contradiction --- if you can already execute code, I'd say you're quite privileged. It's unfortunate that their demo doesn't itself run in the browser using JS (I don't know if it's possible), because that's closer to what people might think of as "unprivileged". The attacker has no control over the address from which data is leaked, therefo…

> if you can already execute code, I'd say you're quite privileged.

I always interpreted "privileged" to mean "superuser". I.e. unrestricted. Or possibly the case of one user and another user. Having a program that can determine the URL you are visiting in the browser from memory when running as the same user is a different class than something that can do the same when run as any non-root user on the system. There's a reason it's common to "drop privileges" in a daemon after any initial setup that requires those privileges (such as binding to a low port).

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#248

Post by nodesocket »

If using a cloud provider with Intel processors:

> The safest workaround to prevent this extremely powerful attack is running trusted and untrusted applications on different physical machines.

Nope!

> If this is not feasible in given contexts, disabling Hyperthreading completely represents the safest mitigation.

Nope!

Shrugs?

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#249

Post by nodesocket »

bigmattystyles wrote: post #153

Why doesn't this type of news cause INTC to tank - they're up today. I know the market is up today, but (and it's probably my innate overreaction) I would think this sort of news would cause its stock to suffer.

I follow the market and tech stocks pretty closely and it is extraditionary rate for breaches, vulnerabilities, or exploits to affect the stock price of companies despite the outrage from the tech community.

Re: ZombieLoad: Cross Privilege-Boundary Data Leakage on Intel CPUs

#250

Post by zelon88 »

So far there seem to be far more of these vulnerabilities in Intel CPUs.

Is that a reflection of engineering differences or a statistical byproduct of the market share of Intel CPUs?

I run AMD not because of the security implications but because I feel every dollar that goes to Intel competition will push Intel and thus the entire industry forward.

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