Basic aspects in redundancy-based intrusion tolerance

This paper addresses intrusion tolerance in ICT systems (that is, how to guarantee the correct operation even when some of its parts are compromised), by adopting a redundancy approach. As an initial step to the process of incorporating redundancy features to enhance robustness of a system/subsystem to cyber attacks that end up with an intrusion, a conceptual framework encompassing the major aspects to be taken into account, regarding both system and redundancy characteristics, is proposed. This is the basis for reasoning on effective redundancy solutions, so a useful support for defining systems that need to satisfy resilience properties in hostile environments where threats include both intentional attacks and accidental faults.