Book excerpt: The 1980's saw the advent of widespread (and potentially damaging) computer virus infection of both personal computer and mainframe systems. The computer security field has been comparatively slow to react to this emerging situation. It is only over the last two years that a significant body of knowledge on the operation, likely evolution and prevention of computer viruses has developed. A Pathology of Computer Viruses gives a detailed overview of the history of the computer virus and an in-depth technical review of the principles of computer virus and worm operation under DOS, Mac, UNIX and DEC operating systems. David Ferbrache considers the possible extension of the threat to the mainframe systems environment and suggests how the threat can be effectively combatted using an antiviral management plan. The author addresses the latest developments in "stealth" virus operations, specifically the trend for virus authors to adopt extensive camouflage and concealment techniques, which allow viruses to evade both existing anti-viral software and to avoid detection by direct observation of machine behaviour. A Pathology of Computer Viruses addresses a distinct need - that of the computer specialist and professional who needs a source reference work detailing all aspects of the computer virus threat.