Masquerade detection by automated means is gaining widespread interest due to the serious impact of masquerades on computer system or network. Several techniques have been introduced in an effort to minimize up to some extent the risk associated with masquerade attack. In this respect, we have developed a novel technique which comprises of Naﶥ Bayes approach and weighted radial basis function similarity approach. The proposed scheme exhibits very promising results in comparison with many earlier techniques while experimenting on SEA dataset in detecting masquerades.