Hackers are using Malware in their attacks and Malware authors are increasingly using hacking techniques so that the difference between the attacks are nearly indistinguishable from the victim's point of view. This book shows how intrusion detection can be applied to various characteristics of Malware and then how anti-virus techniques apply well to some intrusion detection problems. Finally, this book explores a hypothetical Active Defense Network, modelled on the 'Danger Model' of invertebrate immune systems, that takes those ideas further and merges Malware and hacker defenses into one unified system.