Instruction Duplication: Leaky and Not Too Fault-Tolerant!

Fault injection attacks alter the intended behavior of microcontrollers, compromising their security. These attacks can be mitigated using software countermeasures. A widely-used software-based solution to deflect fault attacks is instruction duplication and n-plication. We explore two main limitations with these approaches: first, we examine the effect of instruction duplication under fault attacks, demonstrating that as fault tolerance mechanism, code duplication does not provide a strong protection in practice. Second, we show that instruction duplication increases side-channel leakage of sensitive code regions using a multivariate exploitation technique both in theory and in practice.