Use of K-Nearest Neighbor Classifier for Intrusion Detection V Rao Vemuri University of California, Davis Wednesday, October 23rd, 15-17, LUCAS room (4th floor) Abstract A new approach, based on the k-nearest neighbor (kNN) classifier, is used to classify program behavior as normal and intrusive. Program behavior, in turn, is represented by frequencies of system calls. Data about system calls is gathered over a session. Each system call is treated as a word and the collection of calls over a session as a document. These documents are then classified using kNN classifier, a popular method in text categorization. This method seems to offer some computational advantages over those that seek to characterize "local" program behavior with individual program profiles. Preliminary experiments with 1998 DARPA BSM audit data show that the kNN classifier can effectively detect intrusive attacks and achieve a very low false positive rate. Timing and scaling properties of this method are currently under investigation. If time permits, I will also present some preliminary results from the use of self-organizing maps to identify Distributed Denial of Service (DDOS) attacks. Brief Biography. Prof. Rao Vemuri received his early education in India and his Ph. D. from the University of California, Los Angeles in 1968. He taught at Purdue University, West Lafayette; State University of New York, Binghamton and worked for RCA and TRW before joining University of California, Davis. His research and teaching interests are in the areas of artificial neural nets, genetic algorithms and machine learning. He is currently on a short visit to Lund University. The goal of this visit is to identify opportunities for bilateral exchange of (undergraduate and graduate) students between the two universities. Short term faculty exchanges to foster better cooperation across nations and cultures is also possible.