Plug Your Volt: Protecting Intel Processors against Dynamic Voltage Frequency Scaling based Fault Attacks

Existing countermeasures to DVFS based fault attacks are overly restrictive because (1) they prevent benign, non-SGX processes from utilizing DVFS, and (2) rely upon a less practical threat model than that of Intel SGX. Consequently, this work proposes a new countermeasure principle to defend against DVFS based fault attacks on modern Intel systems. First, we establish that the fundamental cause of DVFS fault attacks is the ability to independently control the frequency and voltage of a processor. Using this observation, we construct a partition of frequency-voltage tuples into unsafe-safe states based on whether a tuple causes timing violations according to switching circuit theoretic principles. Our countermeasure completely prevents DVFS faults on three Intel generation CPUs: Sky Lake, Kaby Lake R, and Comet Lake. Further, it can also be deployed both as microcode or as model-specific registers at the hardware level, unlike previous countermeasures. Our countermeasure incurs a slowdown of only 0.28% on overall system performance when benchmarked against SPEC2017.