CCIE Security v3.0 Quick Reference

Chapter 8. Security Solutions

Viruses, Trojans, Worms, and Spyware

Viruses

A virus is a malicious computer program written with the goal of harming the host it attaches to and executes on. Once they are resident in memory, viruses often delete and modify important files on the infected computer.

Successful viruses require the program to be executed by executing a program or during computer restart. When run, viruses might infect other programs on your hard disk by copying themselves onto them. Viruses can delete files, erase programs, or destroy all data on a disk.

Viruses usually attack the host’s executable program files, its file-directory system (which tracks the location of your entire computer’s files), its boot and system areas that are ...