Shielding Performance Monitor Counters: a double edged weapon for safety and security

Recent years have witnessed the growth of the adoption of Cyber-Physical Systems (CPSs) in many sectors such as automotive, aerospace, civil infrastructures and healthcare. Several CPS applications include critical scenarios, where a failure of the system can lead to catastrophic consequences. Therefore, anomalies due to failure or malicious attacks must be timely detected. This paper focuses on two relevant aspects of the design of a CPS: safety and security. In particular, it studies how performance monitor counters (PMCs) available in modern microprocessors can be from the one hand a valuable tool to enhance the safety of a system and, on the other hand, a security backdoor. Starting from the example of a PMC based safety mechanism, the paper shows the implementation of a possible attack and eventually proposes a strategy to mitigate the effectiveness of the attack while preserving the safeness of the system.