Maximum Linux Security

Chapter 6. Malicious Code

This chapter examines one of the more insidious threats to your system security: malicious code.

What Is Malicious Code?

Malicious code is

• Unauthorized code (contained within a legitimate program) that performs functions unknown to (and probably unwanted by) the user

• A legitimate program that has been altered by the placement of unauthorized code within it that performs functions unknown (and probably unwanted)

• Any program that appears to perform a desirable and necessary function but that (because of unauthorized code within it) performs functions unknown to (and probably unwanted by) the user

• Unauthorized code designed to conceal itself and destroy your data

Many different kinds of malicious code exist but the following are ...