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Re: [LUG] Spectre-NG

 

mr meowski wrote:
>
> "New flaws and even more patches - "Spectre Next Generation"

It was always going to be the case that further flaws were waiting to be
found, sorry if I didn't mention it, I certainly spelt it out at work. It
was also clear that some were unlikely to be fixable without new hardware.

There are unmitigated hardware side channel attacks in most computer
hardware, always has been, probably will be for the foreseeable. It is
just not a big enough risk for most people to engineer against, versus say
slowing the computer down. Just look how long it has taken to have a
reasonable assurance that memory allocation calls won't give you other
people's data left over in memory (Heartbleed anyone).

In the case of these CPU based attacks most are only exploitable if you
run arbitrary untrusted software on the same CPU as you do private stuff.

The commonest case of this was JavaScript, and with the browsers reducing
the precision of the JavaScript time resolution a lot of these are
harder/impossible to exploit via JavaScript.

These days the common case of sharing a CPU with untrusted parties is
probably cloud based Infrastructure as a Service - e.g. AWS EC2, Azure,
etc.

If they are a concern the obvious approach is to reserve CPUs, so that it
is in effect a private Cloud solution in a public cloud. I expect Amazon
and Microsoft are big enough to have someone worrying about CPU allocation
algorithms and other mitigations above CPU firmware fixes.

I noticed, mentioning no names, one of the TLS termination devices we use
allows me to switch off the Spectre mitigation stuff, and rightly so. If
there is untrusted code running on that box we have lost, but the
reduction in CPU performance still hurts.

I've seen some academic exploits, but I largely treat most of this as dark
magic, that is hard to exploit in the real world, and when you meet an
attacker who can you are getting pwned anyway, probably by something much
more mundane.


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