Live data from Hacker News

Downfall Attacks

downfall.page

151–160 of 349 posts

Re: Downfall Attacks

#151

What I find odd is that after the initial Spectre attacks, there have been a long string of these attacks discovered by outside researchers and then patched by the chipmakers. In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal ma…

>In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal machine-readable specifications for the low-level operations of these chips. I hope you're not in charge of hiring QA. Bugs are often found by people who AREN'T thinking like th…

I'm not directly in charge of hiring QA, no!

I think this sort of excuses the initial blindness to Spectre style attacks in the first place, but once the basic pattern was clear it doesn't excuse the subsequent lack of discovering any of the subsequent issues.

It is as if someone found a bug by examining the assembly language of your process which was caused by unsafe inlined `strcpy` calls (though they could not see the source, so they had no idea strcpy was the problem), and then over a the subsequent 6 years other people slowly found more strcpy issues in your application using brute-force black-box engineering and meanwhile you never just grepped your (closed) source for strcpy uses and audited them or used many of the compiler or runtime mitigations against this issue.

Re: Downfall Attacks

#152

What I find odd is that after the initial Spectre attacks, there have been a long string of these attacks discovered by outside researchers and then patched by the chipmakers. In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal ma…

This could be a case of survivorship bias - we don't know how many spectre-like bugs did get patched, because they never made it to the public

We also don't know how many are still out there unreported and part of the secret zero-day caches of various intelligence agencies.

Re: Downfall Attacks

#153

Earlier quoted context omitted.

>In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal machine-readable specifications for the low-level operations of these chips. I hope you're not in charge of hiring QA. Bugs are often found by people who AREN'T thinking like th…

I'm not directly in charge of hiring QA, no! I think this sort of excuses the initial blindness to Spectre style attacks in the first place, but once the basic pattern was clear it doesn't excuse the subsequent lack of discovering any of the subsequent issues. It is as if someone found a bug by examining the assembly language of your process which was caused by unsafe inlined `strcpy` calls (though they could not see…

That still seems like a job for QA and you do have a good point. If there's an attack using one technique, there should be an audit to make sure that technique can't be modified to be used in other nasty ways, then have those tests part of the test suite.

Re: Downfall Attacks

#155

Earlier quoted context omitted.

This could be a case of survivorship bias - we don't know how many spectre-like bugs did get patched, because they never made it to the public

I considered this, but we have pretty good evidence that the chipmakers have not been busily secretly patching Spectre attacks: 1) Microcode updates are visible and Spectre fixes are hard to hide: most have performance impacts and most require coordination from the kernel to enable or make effective (which are visible for Linux). There have been a large number of microcode changes tied to published attacks and corres…

You don't need to patch the errors found during the initial R&D. The patch was made before the hardware was ever sold.

What's left are the attack vectors that Intel's greatest minds didn't discover.

Re: Downfall Attacks

#156

What I find odd is that after the initial Spectre attacks, there have been a long string of these attacks discovered by outside researchers and then patched by the chipmakers. In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal ma…

My guess: There are a lot more researchers on the outside than inside. And also incentives - you would need a red team at Intel who tries to attack their own chips, and those people would be even fewer. And the best people may want to stay independent.

Re: Downfall Attacks

#157

What I find odd is that after the initial Spectre attacks, there have been a long string of these attacks discovered by outside researchers and then patched by the chipmakers. In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal ma…

It's probably that they are aware of several vulnerabilities, such is life. But they are unable to prioritize them and assess which to solve first, they need external auditors using black box techniques to help them identify which are exploitable by external attackers, so they can fix that one, and not the other non issues

Re: Downfall Attacks

#159

What I find odd is that after the initial Spectre attacks, there have been a long string of these attacks discovered by outside researchers and then patched by the chipmakers. In principle it seems like the chipmakers should hold all the cards when it comes to discovery: they are experts in speculative execution, know exactly how their chips work and have massive existing validation suites, simulators and internal ma…

an easier explanation is that modern chipsets are incredibly complex, side channel attacks like these are hard to reason about and traditionally, processors themselves have not been the target of these kinds of attacks, so i don’t think the engineers working on them are accustomed to thinking about them as attack surfaces in this way.

Re: Downfall Attacks

#160
So it seems like speculative execution cannot be disabled. What’s the mitigation here? Nothing and wait for patch or significant redesign?
Post reply on HN