Tn this paper we describe a data mining framework for constructing intrusio
n detection models. The first key idea is to mine system audit data for con
sistent: and useful patterns of program and user behavior The other is to u
se the set of relevant system features presented in the patterns to compute
inductively learned classifiers that can recognize anomalies and known int
rusions. In order for the classifiers to be effective intrusion detection m
odels, we need to have sufficient audit data for training and also select a
set of predictive system features. We propose to use the association rules
and frequent episodes computed from audit data as the basis for guiding th
e audit data gathering and feature selection processes. We modify these two
basic algorithms to use axis attribute(s) and reference attribute(s) as fo
rms of item constraints to compute only the relevant patterns. In addition,
we use an iterative level-wise approximate mining procedure to uncover the
low frequency but important patterns. We use meta-learning as a mechanism
to make intrusion detection models more effective and adaptive. We report o
ur extensive experiments in using our framework on real-world audit data.