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Simple, state-based approaches to program-based anomaly detection

This article describes variants of two state-based intrusion detection algorithms from Michael and Ghosh [2000] and Ghosh et al. [2000], and gives experimental results on their performance. The algorithms detect anomalies in execution audit data. One is a simply constructed finite-state machine, and the other two monitor statistical deviations from normal program behavior. The performance of these algorithms is evaluated as a function of the amount of available training data, and they are compared to the well-known intrusion detection technique of looking for novel n-grams in computer audit data.