Towards Practical Intrusion Tolerant Systems

In this paper, we present the blueprint of a novel middleware infrastructure that can be used to build mission-critical systems with increased resiliency against intrusion attacks. The infrastructure is designed to be practical and it imposes a well-defined structure on the application by adhering the principle of the separation of concerns: (1) the processing of each application request is carried out at a single execution node, and if the execution node becomes faulty, another node can take over immediately; (2) the state of the server is replicated transparently across a pool of state replicas, and a novel append-only strategy is used so that not only the state is protected against hardware failures, it is resilient to attacks aimed to cause state corruption and destruction; (3) the fault monitoring, execution and state integrity checking, and system configuration management are carried out by distinct components which by themselves are replicated.