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>are there many clouds that still run workloads from different users on the same physical core? There are a vast number of VPS providers out there that aren’t

>are there many clouds that still run workloads from different users on the same physical core? There are a vast number of VPS providers out there that aren’t AWS/GCP/Azure/etc where the answer is yes. Even the ones that sell ‘dedicated’ cores, which really just means unmetered cpu

H8crilA 3y ago
What about burstable instances on AWS, and whatever is the equivalent in other clouds? Hard to imagine those having a dedicated core, would probably defeat the purpose.
- watermelon0 3y ago
  Not just burstable instances. AWS Fargate, container as a service, allows specifying 0.25 or 0.5 CPU, and I would be surprised if those weren't shared. Same probably? also applies to AWS Lambda.
  - tracker1 3y ago
    My guess is there's likely less value in trying to target those kinds of environments... Just poking random data out of lambda or low end vps neighbors is a needle in a haystack the size of the moon in terms of finding anything useful. It's more likely useful as part of a group of exploits to hit an individual, targeted system.
    - TrapLord_Rhodo 3y ago
      >Just poking random data out of lambda or low end vps neighbors is a needle in a haystack the size of the moon in terms of finding anything useful. LLM's might change that. getting a firehouse of data and asking it to classify controls against NIST 53- rev5 produces interesting results.
  - c2h5oh 3y ago
    Worse: by default it's not CPU but VCPU - a single core with multithreading = 2 VCPU
- schlarpc 3y ago
  https://docs.aws.amazon.com/whitepapers/latest/security-design-of-aws-nitro-system/the-ec2-approach-to-preventing-side-channels.html#:~:text=However%2C%20even%20burstable%20instances%20never%20share%20the%20same%20core%20at%20the%20same%20time%2C%20and%20virtual%20memory%20pages%20are%20never%20shared%20across%20instances https://docs.aws.amazon.com/whitepapers/latest/security-desi....
ajross 3y ago
Per the paper, this looks like an attack against speculated instructions that modify the store forward buffer. The details aren't super clear, but that seems extremely unlikely to survive a context switch. In practice this is probably only an attack against hyperthread code running simultaneously on the same CPU, which I'd expect cloud hosts to have eliminated long ago.
- acdha 3y ago
  Yeah, the way AWS has stock language like “AWS has designed and implemented its infrastructure with protections against this class of issues” supports the idea that you’re probably not getting anywhere with exploits of this class on a major cloud host any more.

H8crilA 3y ago

What about burstable instances on AWS, and whatever is the equivalent in other clouds? Hard to imagine those having a dedicated core, would probably defeat the purpose.

watermelon0 3y ago
Not just burstable instances. AWS Fargate, container as a service, allows specifying 0.25 or 0.5 CPU, and I would be surprised if those weren't shared. Same probably? also applies to AWS Lambda.
- tracker1 3y ago
  My guess is there's likely less value in trying to target those kinds of environments... Just poking random data out of lambda or low end vps neighbors is a needle in a haystack the size of the moon in terms of finding anything useful. It's more likely useful as part of a group of exploits to hit an individual, targeted system.
  - TrapLord_Rhodo 3y ago
    >Just poking random data out of lambda or low end vps neighbors is a needle in a haystack the size of the moon in terms of finding anything useful. LLM's might change that. getting a firehouse of data and asking it to classify controls against NIST 53- rev5 produces interesting results.
- c2h5oh 3y ago
  Worse: by default it's not CPU but VCPU - a single core with multithreading = 2 VCPU
schlarpc 3y ago
https://docs.aws.amazon.com/whitepapers/latest/security-design-of-aws-nitro-system/the-ec2-approach-to-preventing-side-channels.html#:~:text=However%2C%20even%20burstable%20instances%20never%20share%20the%20same%20core%20at%20the%20same%20time%2C%20and%20virtual%20memory%20pages%20are%20never%20shared%20across%20instances https://docs.aws.amazon.com/whitepapers/latest/security-desi....

ajross 3y ago

Per the paper, this looks like an attack against speculated instructions that modify the store forward buffer. The details aren't super clear, but that seems extremely unlikely to survive a context switch. In practice this is probably only an attack against hyperthread code running simultaneously on the same CPU, which I'd expect cloud hosts to have eliminated long ago.

acdha 3y ago
Yeah, the way AWS has stock language like “AWS has designed and implemented its infrastructure with protections against this class of issues” supports the idea that you’re probably not getting anywhere with exploits of this class on a major cloud host any more.