State that a computer virus consists of code segments that perform malicious actions. Point out to students that one of the most common methods of virus transmission is via e-mail attachments.
Mention that viruses can be classified by how they spread themselves. Discuss the most common types of information system viruses, which are the macro virus and the boot virus.
Explain the classification known as memory-resident and non-memory-resident viruses. Note that resident viruses are capable of reactivating when the computer is booted and continuing their actions until the system is shut down.
Differentiate between different types of attack replication vectors illustrated in Table 2-8 within the text and stress that regardless of which one is used, the impact can still be crippling to an organization.