Security: good ;login: preprint article on the ‘Witty’ worm. ‘Conclusion: Witty represents a new generation of malcode: written by a motivated, skilled, and malicious individual. Witty’s author is the first to combine both skill and substantial malice. The author had some motive which lead, for him, to desire a destructive effect. Witty was written by an expert and, unless caught, he could do it again.’