Modern Intrusion Detection, Data Mining, and Degrees of Attack Guilt

This chapter examines the state of modern intrusion detection, with a particular emphasis on the emerging approach of data mining. The discussion parallels two important aspects of intrusion detection: general detection strategy (misuse detection versus anomaly detection) and data source (individual hosts versus network traffic). Misuse detection attempts to match known patterns of intrusion, while anomaly detection searches for deviations from normal behavior. Between the two approaches, only anomaly detection has the ability to detect unknown attacks. A particularly promising approach to anomaly detection combines association mining with other forms of machine learning such as classification. Moreover, the data source that an intrusion detection system employs significantly impacts the types of attacks it can detect. There is a tradeoff in the level of detailed information available versus data volume. We introduce a novel way of characterizing intrusion detection activities: degree of attack guilt. It is useful for qualifying the degree of confidence associated with detection events, providing a framework in which we analyze detection quality versus cost.