The Principles of system security
Q. What is a virus?
A. A Virus is a program that reproduces itself. It may attach itself to other programs, it may create copies of itself, it may damage or corrupt data, change data, or degrade the performance of your system by utilizing resources such as memory or disk space. Some Virus scanners detect some Viruses. No Virus scanners detect all Viruses. Virus scanners will work for a while but people are always creating ways that will beat them.
Q. What is a worm?
A. Worms are programs that copy themselves over and over using up space and slowing down the system. They are self-contained and use the networks to spread, in much the same way that viruses use files to spread.
Q. What is a Trojan?
A. The term comes from a story in Homer's Iliad, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy. A Trojan is a program, which does an unauthorized function, hidden inside an authorized program. It does something other than it claims to do.
The most insidious Trojan is a program opening your computer to outside "administration", while you are connected to Intranet, or Internet. Virus scanning programs, like Norton, will not detect Trojan. It takes a special kit of programs to detect, kill, or double-cross a Trojan. The last, traps the identity of a remote "administrator".
Trojans are most often used for covert surveillance or corporate / industrial espionage. In this case you may never know that your security and information your computer(s) hold was compromised. The only cure is prevention. Install software blocking "back orifice" on Windows operating system, or switch to Unix or Linux operating system.
If this sounds like Chinese to you… it's a time to look for a computer security expert.
adapted by Rafal Swiecki, p. eng. email
This document is in the public domain.