Computer Viruses : What They are & Where They Come From
So, what exactly is a computer virus?
In the simplest of terms a computer virus is nothing more than a computer program which is capable of making a copy of itself and spreading by moving from one computer to another attached to a host. A computer virus is not necessarily intent on doing any real harm. In fact, the program which is usually credited with being the very first computer virus ever written (Creeper) was simply an experimental program written by Bob Thomas at a company called BBN Technologies in Cambridge, Mass. in 1971. This first computer virus distributed itself over ARPANET ( the forerunner of the Internet as we know it today) and simply displayed the words "I'm the creeper, catch me if you can!" on the infected computer.
Despite the light-hearted and non-destructive nature of this and some other early programs which fall into the virus category, the vast majority of modern computer viruses are quite determined to wreak havoc on your machine as well as on as many others as they can. Although it is theoretically possible for a virus to infect any computer which is capable of executing a program, nearly all of those in existence today are designed to target personal computers (PC) running the Microsoft Windows operating system (OS).
Where do computer viruses come from?
As I stated earlier, computer viruses are merely computer programs (albeit with some specialized abilities and ulterior motives). As such, they come from the same place that all computer programs come from -- they are written by computer programmers! The next logical question would seem to be "why would someone program such a thing in the first place?" I suppose the answers to that question are as numerous as the programmers who write the virus programs. Even so, it is certainly safe to say that the reasons someone might have for writing a computer virus program fall into one or more of a handful of categories. These reasons most often include things like:
- A challenge - simply to see if they can do it
- Out of a dislike for Microsoft or some other company
- boredome - (really)
- For criminal gain and to make a profit
- For research (that is what they say anyway!)
Some common symptoms of a virus infection
Just like the underlying motivation of the programmer in writing the virus to start with, the possible actions of a computer virus are limited only by the imagination. There are some common side effects to watch for however which might indicate the presence of a computer virus on your system. If any of the following symptoms apply to your computer, it is advisable to run a complete system scan using an up to date anti-virus program. Common symptoms of a virus infection include:
- Your computer runs unusually slow or freezes
- People are receiving emails from you which you did not send
- You get pop-up messages or advertisements
- Slower than usual network or Internet speed
- Files mysteriously appear or disappear from your computer
- Your homepage changes and you can not change it back
- Your hard drive free space keeps shrinking
How are computer viruses spread?
Well, unlike the viruses which make us sick, they do not simply float around in the air or spread via sneezes and such! Computer viruses need a host file to attach themselves to. The host file must be "executable" which means that it must be a type of file which is capable of performing some action and not simply a text file or an image. When an infected host file is transported from 1 computer to another the second machine becomes infected. Because of this, viruses are often spread via email attachments, through html code on a web-page, or by sharing files between computers over a network or with a removable media such as a USB thumb drive.
The people responsible for creating these nasty little vermin are constantly coming up with new ways to sneak the virus files onto the computers of unsuspecting people. They try to stay 1 step ahead of the anti-virus software and to come up with delivery methods for the viruses that happen without the user even knowing. Because of this, the only 100% foolproof method of staying virus free is to be sure that all of the software you install is uninfected and to keep the machine isolated from other computers. In other words, do not use it for email, sharing files, or accessing web pages! This is, in all honesty, simply not a feasible solution. So, how does one at least minimize the risk of being infected by a computer virus?
Read my article on minimizing the threat from computer viruses and malware to find out!