Security Power Tools

Chapter 16. Email Security and Anti-Spam

There is a wide array of malicious software ( malware) available that is designed to damage your computer, take control of systems, or gather personal information. Here are some types of malware, although these examples in no way cover all the possible varieties that malicious people create:

Virus

A virus is a self-replicating program that inserts copies of itself in other computer programs (usually executables) or documents (for example, office documents with macros). Viruses often use email to spread across a network. Polymorphic viruses modify themselves each time, making them harder detect. Bombs are viruses that start acting on a given date (time bomb ) or with a given action by the user (logic bomb ).

Worm

A worm is similar to a virus, but worms use vulnerabilities in networking to spread (for example, Slammer exploited a vulnerability in the Microsoft SQL Server, and Sasser exploited a vulnerability in Microsoft Active Directory).

Trojan/Backdoor/RAT

A Trojan, backdoor, or Remote Administration Tool (RAT) allows unauthorized persons to take partial or complete control of an infected system. Unlike viruses or worms, they cannot replicate themselves. They often lie inside programs downloaded from obscure web sites or from peer-to-peer networks.

Spyware

The term spyware includes a wide range of software aimed at spying on the user. Spyware usually does not replicate itself, but it can download other spyware to your computer. Spyware is becoming ...