Single Instruction Multiple Data Leaks in Cutting-edge CPUs, AKA Downfall

We introduce Downfall attacks, new transient execution attacks that undermine the security of computers running everywhere across the internet. We exploit the "Gather" instruction on high-performance Intel CPUs to leak data across boundaries of user-kernel, processes, virtual machines, and trusted execution environments. Our findings, exploitation techniques, and demonstrated attacks defeat all previous defenses, calling for critical hardware fixes and security updates for widely-used client and server computers.
In this talk, we first discuss the SIMD Gather instruction, how to exploit it to leak data from internal physical CPU registers via Gather Data Sampling (GDS) and how this vulnerability affects various instructions and workloads....
By: Daniel Moghimi
Full Abstract and Presentation Materials: www.blackhat.c...