Computer Virus Information


Computer viruses are malicious programs (or sets of instructions) which are designed to replicate themselves from machine to machine. Viruses may evolve over time if they are designed to change their own content as they replicate or if they are changed by someone who has access to the code. Viruses may also contain destructive code. These programs are generally designed to make changes to software that already exists on the system thus enabling them to replicate themselves, display messages, destroy data or software, or inhibit access by the user of the system.

Computer viruses can be a serious threat to an organization since they usually result in lost time and effort required to clean and restore infected systems. Viruses are a threat because:


How can you tell if your machine is infected?

Recognizing that a system is infected by a virus depends on the type of virus itself. Some examples of known viruses and their effect include:

Some viruses, most notably "stealth" viruses, hide themselves on a system and are triggered on a specific date, for example the Friday the 13th Virus. Some viruses may result in slower response time as they tie up your system's resources. Others can prevent you from accessing files by altering directories and file tables.


How can a machine become infected?

The PC environment is not controlled like a mainframe computer environment. Sharing of Personal Computers, MACs and diskettes is quite common. There are a number of ways in which a machine can become infected, including:


What should you do if you suspect that a virus has infected your machine?


What can you do to prevent your machine from becoming infected?

There are some very basic things you can do to prevent viral infections. Safe computing is relatively easy to achieve. The following guidelines will help you practice safe computing: