An analytical framework for reasoning about intrusions

Local and wide area network information assurance analysts need current and precise knowledge about their systems activities in order to address the challenges of critical infrastructure protection. In particular, the analyst needs to know in real-time that an intrusion has occurred so that an active response and recovery thread can be created rapidly. Existing intrusion detection solutions are basically after-the-fact, thereby offering very little in terms of damage confinement and restoration of service. Quick recovery is only possible if the assessment scheme has low latency and it occurs in real-time. The objective of this paper is to develop a reasoning framework to aid in the real-time detection and assessment task that is based on a novel idea of encapsulation of owner's intent. The theoretical framework developed here will help resolve dubious circumstances that may arise while inferring the premises of operations (encapsulated from owner's intent) by way of examining the observed conclusions resulting from the actual operations of the owner. This reasoning is significant in view of the fact that intrusion signaling is not a binary decision unlike error detection in traditional fault tolerance. Our reasoning framework has been developed by leveraging the concepts of cost analysis and pricing under uncertainty found in economics and finance. Our main result is the modeling of user activity on a computing system as a martingale and the subsequent quantification of the cost of performing a job to enable decision making.