Re:Zenbleed
by beebmam on Monday July 24, 2023 @11:32AM
(#36849631)
It is very clear, you just didn't read it.
>We now know that basic operations like strlen, memcpy and strcmp will use the vector registers - so we can effectively spy on those operations happening anywhere on the system! It doesn’t matter if they’re happening in other virtual machines, sandboxes, containers, processes, whatever!
>This works because the register file is shared by everything on the same physical core. In fact, two hyperthreads even share the same physical register file.
>It turns out that mispredicting on purpose is difficult to optimize! It took a bit of work, but I found a variant that can leak about 30 kb per core, per second.
>This is fast enough to monitor encryption keys and passwords as users login!
>We now know that basic operations like strlen, memcpy and strcmp will use the vector registers - so we can effectively spy on those operations happening anywhere on the system! It doesn’t matter if they’re happening in other virtual machines, sandboxes, containers, processes, whatever!
>This works because the register file is shared by everything on the same physical core. In fact, two hyperthreads even share the same physical register file.
>It turns out that mispredicting on purpose is difficult to optimize! It took a bit of work, but I found a variant that can leak about 30 kb per core, per second.
>This is fast enough to monitor encryption keys and passwords as users login!