Intro to computer virus
Intro to computer virusVirus
What is a Virus?
The computer virus is something that has been around almost as long as the Personal Computer (PC) and certainly since the advent of the affordable home computer, but what exactly is a virus? And how does it affect your PC? Is there any way to prevent your hard drive becoming infected and just where do they come from anyway?
A virus is computer program, usually a very small program, that interferes with the smooth running of a computer's operating system and hardware. Viruses are designed to copy themselves and hide within your computer to avoid detection.
In 1995 Ernst & Young released a security survey that showed that 67% of all companies had virus attacks. That was a rise from 54% in 1994. The cost of each attack was estimated at $13, 000.
The NSCA (National Computer Security Association) reported in January of 1997 that 200 macro viruses had been discovered. Six months later the amount of macro viruses had risen by over 300%.
At this stage it is estimated that 90% of all companies have at least one macro virus resident somewhere in their computer systems.
Types of Viruses
Under the main heading of viruses are three types of harmful computer programs, not all of which hide and replicate.
The first of these is the Trojan Horse programs, the name of which comes from the Greek legend that told how Greek soldiers gained entry to the city of Troy in a giant, hollow wooden horse and thus captured the city, ending the Trojan War. Though not technically a virus it is still dangerous and could cause permanent damage to your operating system. A Trojan Horse program is a program disguised as a game, a utility or an application. When run, a Trojan Horse will do something devious to your computer while appearing to do something useful, such as deleting every file beginning with the letter 'H' while you are running a word processing program.
A logic bomb is a program that lies dormant in a computer's memory until certain conditions are met, such as a date is reached, a certain program is activated, or a combination of letters is typed. An example of this is the 'Bomber' virus. Every August 31st this virus activates, emits a beep and writes the message 'I am the stealth bomber' to the computer screen.
A worm program replicates itself across computer systems, usually leaving copies of itself in the memory of any computer it comes across. Sometimes a worm copies itself so much that it fills up the computer's memory, slowing it down and sometimes causing it too crash.
Within these main types there are sub-types including, but not limited to:
Boot Viruses that can affect the start up procedure of your computer...
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