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The pervasive interconnection of systems throughout the world has given computer services a significant socioeconomic value that both accidental faults and malicious activity can affect. The classical approach to security has mostly consisted of trying to prevent bad things from happening-by developing systems without vulnerabilities, for example, or by detecting attacks and intrusions and deploying ad hoc countermeasures before any part of the system is damaged. Building an intrusion-tolerant system to arrive at some notion of intrusion-tolerant middleware for application support presents multiple challenges. Surprising as it might seem, intrusion tolerance isn't just another instantiation of accidental fault tolerance
Verı́ssimo et al. (Sat,) studied this question.