Computer Viruses: Overview and Defense

As computers become more advanced the software needed to run them becomes equally complex and intricate. The features we've come to need and expect for productivity can also be a gateway for many types of malicious programs such as viruses, worms and scripts that are designed to take advantage of loop holes in the program's code and cause problems on your computer.


What is a virus?

By definition a virus is a malicious piece of code or a small program that causes the computer (or any program on it) to act in a manner it was not designed to do. This also means that a virus can destroy data, render the computer inoperable by altering the boot sector or vital operating system files. Unlike the biological world the computer world has no beneficial viruses, in the best case a virus would be a simple annoyance like a little note popping up, however the other side of the mirror sees the virus destroying files across a network, replicating itself to hundreds of other networks and/or emailing itself to co-workers, friends, family and business contacts. Regardless of the kind of virus, they are all threats to security.

In 'older' times (around 1990 to 1996) Computer viruses were very simple affairs that would be 'delivered' by the use of an infected executable program, however more recent viruses are vastly more complex and include the ability to hide themselves in the boot sector of a floppy disk (or the hard disk of your PC), within email attachments, email signatures, and even documents. With all these possible methods of delivery the question of *using* anti-virus software isn't so much a question as it is *which* anti-virus software to use.

Types of Viruses

Today's computer viruses can be divided into three main categories, though there are hundreds (if not thousands) of minor variations on the archetypes.

Macro Viruses