Botnets have become the platform of choice for launching attacks and committing fraud on the Internet. A better understanding of Botnets will help to coordinate and develop new technologies to counter this serious security threat. Botnet Detection: Countering the Largest Security Threat, a contributed volume by world-class leaders in this field, is based on the June 2006 ARO workshop on Botnets. This edited volume represents the state-of-the-art in research on Botnets. It provides botnet detection techniques and response strategies, as well as the latest results from leading academic, industry and government researchers. Botnet Detection: Countering the Largest Security Threat is intended for researchers and practitioners in industry. This book is also appropriate as a secondary text or reference book for advanced-level students in computer science.