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De we even have a Proof of concept for the MDS attacks (one that doesn't require other thread to be writing the same data over and over in a loop)? So much of

De we even have a Proof of concept for the MDS attacks (one that doesn't require other thread to be writing the same data over and over in a loop)? So much of this seems driven by Intel hate, and while hardware manufacturers should work on mitigation, it shouldn't be done at the expense of performance, especially for machines that don't run untrusted code (even then, I'm not sure it should be done unless the cost is extremely minimal). JavaScript/WASM is being used as a bogey man, when the overwhelming evidence is that it just isnt possible to exploit the browser with enough consistency to make it work when not assisted. The meltdown POC was more a "look at this neat thing I an do if I set everything up perfectly" - set up to such an artificial extent that it wasn't even applicable to any computer system. The the one MDS attack I saw required the target to repeatedly write the same byte of memory in loop while being attacked. This isn't going to happen. These MDS attacks at best seem to be able to pick fairly random bytes, and they can only do it while the data they are snooping on is in the load/store buffer, so they can't even run the number of times required to exfiltrate the data consistently. I haven't seen a single piece of code that will, for example, grap SSH keys from a running ssh program using one of these attacks. From Javascript in a browser? LOL. While these are very cool and interesting, they arent anything to be worried about, especially if you don't run a cloud service. Oh, but right, Intel hate.

rayiner 7y ago
The Intel hate is really misdirected. The entire industry had an incorrect mental model of what process isolation required. All that an x86 CPU promises is that you will get a page fault if you try to access privileged memory. That’s it, and it’s not sufficient for process isolation in the face of malicious code. JavaScript/WASM VMs assumed more or less the same thing. So long as you can catch any out-of-bound array reads or the like, you have a safe “sandbox.” Again, that assumption was insufficient. It wasn’t just Intel and JavaScript developers either. Entire bodies of research were dedicated to techniques that likely would be vulnerable to these sorts of attacks. For example, the idea that you could do away with CPU memory protection if you ran everything in a managed language that makes it impossible to access arbitrary memory. What you’re seeing as a paradigm shift in what kinds of process isolation are required for modern computing.
- zrm 7y ago
  The Intel hate is somewhat consequentialist. Software was written under a security assumption that wasn't true, the alternative code is slower. Whose fault it is and the ramifications for the relative performance between different processor designs are separate matters, and people understandably aren't going to favor the vendor with the larger performance loss.
- cookiecaper 7y ago
  While it's true that speculation as a whole needs to be revisited, Intel is impacted to a much greater extent because they designed their hardware to speculate beyond permission barriers as a matter of routine. AMD did not [0] and consequently is affected only by the most general attacks on speculation, e.g., Spectre. As far as I understand, AMD chips are not impacted by Meltdown or any of the MDS attacks. It'd be great to see Michael run the same benchmarks against an AMD chip that has all relevant mitigations enabled and compare the performance loss. I'd ballpark that AMD chips may have lost ~10% overall, whereas we see here that Intel chips have lost ~25%. [0] https://www.amd.com/system/files/documents/security-whitepaper.pdf https://www.amd.com/system/files/documents/security-whitepap...
icedchai 7y ago
Yep. Practically speaking, it's mostly not worth worrying about. You might be able to read a few bytes every second, assuming perfect conditions (minimal context switching, etc.) It doesn't keep me up at night. But, our computers are going to be running slower now... "just in case."

rayiner 7y ago

The Intel hate is really misdirected. The entire industry had an incorrect mental model of what process isolation required. All that an x86 CPU promises is that you will get a page fault if you try to access privileged memory. That’s it, and it’s not sufficient for process isolation in the face of malicious code. JavaScript/WASM VMs assumed more or less the same thing. So long as you can catch any out-of-bound array reads or the like, you have a safe “sandbox.” Again, that assumption was insufficient. It wasn’t just Intel and JavaScript developers either. Entire bodies of research were dedicated to techniques that likely would be vulnerable to these sorts of attacks. For example, the idea that you could do away with CPU memory protection if you ran everything in a managed language that makes it impossible to access arbitrary memory. What you’re seeing as a paradigm shift in what kinds of process isolation are required for modern computing.

zrm 7y ago
The Intel hate is somewhat consequentialist. Software was written under a security assumption that wasn't true, the alternative code is slower. Whose fault it is and the ramifications for the relative performance between different processor designs are separate matters, and people understandably aren't going to favor the vendor with the larger performance loss.
cookiecaper 7y ago
While it's true that speculation as a whole needs to be revisited, Intel is impacted to a much greater extent because they designed their hardware to speculate beyond permission barriers as a matter of routine. AMD did not [0] and consequently is affected only by the most general attacks on speculation, e.g., Spectre. As far as I understand, AMD chips are not impacted by Meltdown or any of the MDS attacks. It'd be great to see Michael run the same benchmarks against an AMD chip that has all relevant mitigations enabled and compare the performance loss. I'd ballpark that AMD chips may have lost ~10% overall, whereas we see here that Intel chips have lost ~25%. [0] https://www.amd.com/system/files/documents/security-whitepaper.pdf https://www.amd.com/system/files/documents/security-whitepap...

icedchai 7y ago

Yep. Practically speaking, it's mostly not worth worrying about. You might be able to read a few bytes every second, assuming perfect conditions (minimal context switching, etc.) It doesn't keep me up at night. But, our computers are going to be running slower now... "just in case."