CertiGuide to Security+  9  Chapter 1:  General Security Concepts (Domain 1.0; 30%)       9  1.5  Malicious Code

1.5.1  Viruses 1 1.5.3  Logic Bombs

This one should tie tightly (at least in your mind) to social engineering. A Trojan horse pretends to be something useful or interesting, yet, is really a virus or other malicious code whose writer decided the best way to distribute it would be to include it in a program that claims to do something useful. Unlike a regular virus, a Trojan horse is attached to a particular executable, and typically isn’t capable of replicating and attaching itself to other files on your system.

Typically the Trojan horse relies on gaining users’ interests with something that sounds fun or curious. Sometimes they masquerade as some sort of data file where a user is asking for help. Because Trojan horses appear to be legitimate code, but have hidden functions designed to do nasty things, they are difficult to detect with an Intrusion Detection System (IDS).

As with viruses, prevention of Trojan horses on your system will largely be accomplished via anti-virus software and educating users not to open mysterious attachments.

1.5.1  Viruses 1 1.5.3  Logic Bombs