10.4 Computer Software PM
10.4.2 Anti-virus
Computer viruses are programs that have been written by people with malicious intent. Once a virus has been released, it can do anything from take control of a computer and leave a message on the screen or completely erase the hard drive.

To prevent a virus from infecting the system, the best defense is an anti-virus application. Anti-virus programs, once installed, can run in the background to make sure a virus is not infecting the computer. They can also be run on command and scan the entire computer or just a specific file for viruses. If a virus is found, the anti-virus software can perform one of two actions. It can clean the infected file, or if it cannot clean the file, it can isolate the file. If a file becomes isolated, or quarantined, the user will not be able to open it. Remember to update the anti-virus program often (or auto-update).

A good defense against viruses is common sense. Viruses are typically sent as e-mail attachments. Once opened, the virus will infect the computer and send itself out using e-mail addresses found in programs like Microsoft Outlook. Other users will assume the e-mail is legitimate, allowing the virus to spread. Be suspicious of e-mail attachments with .exe extensions. When in doubt, contact the sender before opening an attachment to verify.

Types of Viruses
Part of defending against a virus is knowing the different types and what they do. Below is a list of the most common forms of viruses:

  • File – One of the most common forms of viruses, file viruses modify an existing program so that upon execution of a seemingly safe program, the malicious intent of the virus is carried out.
  • Boot Sector – This kind of virus targets the boot sector of every floppy or hard disk. If the boot sector of the primary hard drive is infected, every time the computer is started, the virus will run.
  • Macro – This type of virus takes advantage of built-in macro programming languages in word processors. Macros automate the formatting of documents and can be quite useful. However, they can also be written to do mischievous or damaging things.

If a computer system is behaving strangely, do not immediately rule out a virus. If anti-virus software is installed, run it to make sure the system is clean. Additionally, schedule anti-virus software to run on a regular basis.