Book excerpt: The runaway growth of computer viruses and worms and the ongoing nuisance posed by malicious hackers and employees who exploit the security vulnerabilities of open network protocols make the tightness of an organization's security system an issue of prime importance. And information systems technology is advancing at a frenetic pace. Against this background, the challenges facing information security professionals are increasing rapidly. Information Security Management Handbook, Fourth Edition, Volume 2 is an essential reference for anyone involved in the security of information systems.