ABSTRACT
This chapter discusses computer viruses. Section 9.1 discusses how viruses work in general. Section 9.2 explains anti-virus tools and theoretical limits on their effectiveness. We provide notional examples of simple viruses in Sections 9.3, and 9.4. Section 9.5 explains limits on the spread of viruses on a single host. These limits explain why current operating systems are ill-suited for containing viruses.
