Machine learning techniques are widely used in many fields. One of the applications of machine learning in the field of the information security is classification of a computer behavior into malicious and benign. Anti viruses consisting on signature-based methods are helpless against new (unknown) computer worms. This paper focuses on the feasibility of accurately detecting unknown worm activity in individual computers while minimizing the required set of features collected from the monitored computer. A comprehensive experiment for testing the feasibility of detecting unknown computer worms, employing several computer configurations, background applications, and user activity, was performed. During the experiments 323 computer features were monitored by an agent that was developed. Four feature selection methods were used to reduce the amount of features and four learning algorithms were applied on the resulting feature subsets. The evaluation results suggests that using classificati...