The Weird Machines in Proof-Carrying Code

Abstract

We review different attack vectors on Proof-Carrying Code (PCC) related to policy, memory model, machine abstraction, and formal system. We capture the notion of weird machines in PCC to formalize the shadow execution arising in programs when their proofs do not sufficiently capture and disallow the execution of untrusted computations. We suggest a few ideas to improve existing PCC systems so they are more resilient to memory attacks.