3 ms·

The only way to exploit these vulnerabilities is to run code on target machines. If that's not possible then the vulnerability is irrelevant. Using firewalls to

The only way to exploit these vulnerabilities is to run code on target machines. If that's not possible then the vulnerability is irrelevant. Using firewalls to keep attackers away from your vulnerable machines is a viable strategy in this case.

paulie_a 9y ago
>if it's not possible to run code We are doomed
ams6110 9y ago
Conventional thinking is that if a malicious user can run code on your system, you've lost. In that sense, this is just another local exploit, of which there are many.
- InclinedPlane 9y ago
  This includes fully sandboxed code, however, which is an important distinction. The fact that a driveby javascript exploit could potentially result in leaking every important secret from your system (logins, encryption keys, what-have-you) is why people are taking this so seriously.
  - petecox 9y ago
    Algorithmically is it possible to pass only 'safe' interpreted code to the CPU? The majority of Javacript engines (Chakra, V8, Spidemonkey and JavasciptCore) are under a security-auditable FOSS license. Browsers claiming Spectre/Meltdown immunity would be in the next release notes, surely. I'm not discounting that CPUs should operate correctly into the future but the current sandboxes would seem to rely on whims of a CPU's microcode. And the question for browser makers is whether to trust them.
    - gruez 9y ago
      >Algorithmically is it possible to pass only 'safe' interpreted code to the CPU? in other words, the halting problem?
      - amock 9y ago
        It's not the halting problem because you can have false positives. If the code can't be proven safe it is rejected.
    - kazagistar 9y ago
      Its not about algorithms. The issue is mentioned in the paper: even if the cache-based side channels are stopped (lets say, by manually clearing any cached memory as soon as its accessed, reducing performance to 0.1% of what it is now) there are other potential side channels like through limited CPU resources. A lot of the "fixes" might just be mitigations, that don't solve the problem entirely, but make it take much longer. Maybe you can cover up enough holes, and make the timers available poor enough that it takes a few hours or days to read a single byte. In other words, mitigations to make things less simple.
  - im3w1l 9y ago
    I assume exploitability through javascript depends very strongly on how the browser treats it. If it's jit-ed to optimal machine code it should be easy. If it's interpreted it should be harder. So question is, can the Javascript engine generate suboptimal but safe machine code?

paulie_a 9y ago

>if it's not possible to run code We are doomed

ams6110 9y ago

Conventional thinking is that if a malicious user can run code on your system, you've lost. In that sense, this is just another local exploit, of which there are many.

InclinedPlane 9y ago
This includes fully sandboxed code, however, which is an important distinction. The fact that a driveby javascript exploit could potentially result in leaking every important secret from your system (logins, encryption keys, what-have-you) is why people are taking this so seriously.
- petecox 9y ago
  Algorithmically is it possible to pass only 'safe' interpreted code to the CPU? The majority of Javacript engines (Chakra, V8, Spidemonkey and JavasciptCore) are under a security-auditable FOSS license. Browsers claiming Spectre/Meltdown immunity would be in the next release notes, surely. I'm not discounting that CPUs should operate correctly into the future but the current sandboxes would seem to rely on whims of a CPU's microcode. And the question for browser makers is whether to trust them.
  - gruez 9y ago
    >Algorithmically is it possible to pass only 'safe' interpreted code to the CPU? in other words, the halting problem?
    - amock 9y ago
      It's not the halting problem because you can have false positives. If the code can't be proven safe it is rejected.
  - kazagistar 9y ago
    Its not about algorithms. The issue is mentioned in the paper: even if the cache-based side channels are stopped (lets say, by manually clearing any cached memory as soon as its accessed, reducing performance to 0.1% of what it is now) there are other potential side channels like through limited CPU resources. A lot of the "fixes" might just be mitigations, that don't solve the problem entirely, but make it take much longer. Maybe you can cover up enough holes, and make the timers available poor enough that it takes a few hours or days to read a single byte. In other words, mitigations to make things less simple.
- im3w1l 9y ago
  I assume exploitability through javascript depends very strongly on how the browser treats it. If it's jit-ed to optimal machine code it should be easy. If it's interpreted it should be harder. So question is, can the Javascript engine generate suboptimal but safe machine code?