Abstract
A large set of machine learning and pattern classification algorithms trained and tested on KDD intrusion detection data set failed to identify most of the user-to-root and remote-to-local attacks, as reported by many researchers in the literature. In light of this observation, this paper aims to expose the deficiencies and limitations of the KDD data set to argue that this data set should not be used to train pattern recognition or machine learning algorithms for misuse detection for these two attack categories. Multiple analysis techniques are employed to demonstrate, both objectively and subjectively, that the KDD training and testing data subsets represent dissimilar target hypotheses for user-to-root and remote-to-local attack categories. These techniques consisted of switching the roles of original training and testing data subsets to develop a decision tree classifier, cross-validation on merged training and testing data subsets, and qualitative and comparative analysis of rules generated independently on training and testing data subsets through the C4.5 decision tree algorithm. Analysis results clearly suggest that no pattern classification or machine learning algorithm can be trained successfully with the KDD data set to perform misuse detection for user-to-root or remote-to-local attack categories. It is further noted that the analysis techniques employed to assess the similarity between the two target hypotheses represented by the training and the testing data subsets can readily be generalized to data set pairs in other problem domains.