Intrusion detection is an essential component of computer security mechanis
ms. It requires accurate and efficient analysis of a large amount of system
and network audit data. It can thus be an application area of data mining.
There are several characteristics of audit data: abundant raw data, rich s
ystem and network semantics, and ever "streaming". Accordingly, when develo
ping data mining approaches, we need to focus on: feature extraction and co
nstruction, customization of (general) algorithms according to semantic inf
ormation, and optimization of execution efficiency of the output models. In
this paper, we describe a data mining framework for mining audit data for
intrusion detection models. We discuss its advantages and limitations, and
outline the open research problems.