Compare and contrast virus and worm.

What will be an ideal response?

A virus is executable code that can replicate itself from one place to another surreptitiously and perform actions that range from benign to harmful. Viruses are spread by several methods, including running executable code, sharing disks or memory sticks, opening e-mail attachments, and viewing infected or malicious Web pages. Viruses can attach to other executables or replace them in order to spread or execute. Viruses require user intervention to run.

A worm creates files that copy themselves repeatedly and consume disk space. Worms do not require user intervention to be launched; they are self-propagating. Some worms can install back doors-a way of gaining unauthorized access to a computer or other resource, such as an unused port or terminal service, that makes it possible for attackers to gain control over the computer.