Lesson 1: Introduction to Viruses

So you've heard a lot about viruses, but you still don't know how it all started, where they come from. In this lesson we will talk about how viruses are created, and why. We will also talk about the most common means of infection for viruses.

Viruses have an impact on the computer they infect and on the people who own the computers. In this lesson we will take a look at some of the costs of viruses.

Life cycle of a virus

Viruses have a distinct life cycle. Beginning when they are created, and ending when they have been completely eradicated. To date no viruses have been completely eradicated, but several have ceased to be a major concern.

The reason no virus to date has been completely eradicated is because the public as a whole is not educated about the importance of safe computing practices. If more people had virus scanners and kept them up to date the chances of eradicating a virus would greatly increase. Remember it is YOUR responsibility to ensure that your computer is safe from viruses, not the store you bought your computer from.

The reason no virus to date has been completely eradicated is because the public as a whole is not educated about the importance of safe computing practices. If more people had virus scanners and kept them up to date the chances of eradicating a virus would greatly increase. Remember it is YOUR responsibility to ensure that your computer is safe from viruses, not the store you bought your computer from.

Once upon a time, on a computer not so very far away, a programmer sat down and wrote a program, this program was evil and spread out from system to system infecting all computers, and disks it came across.

A programmer programs viruses intentionally. You cannot accidentally create a virus. You can however accidentally pass on a virus to another. As to why a programmer would program a virus, only the creators of the viruses themselves can answer that question, and they generally do not want to admit they even created the program since it is illegal. The most common theory is that the programmer is a disgruntled employee who wishes to get back at their employer for some perceived injustice, the create a virus and release it into their employers network. Another common theory is that virus writers write viruses to prove they can, this type of virus programmer is usually young and immature, they are creating and releasing the virus to see how much they can get away with. It used to be quite difficult to write a virus, you needed allot of specialized knowledge to do so. In today's world, however, there are easily accessible programs for creating viruses. This means that almost anyone can write a virus with little knowledge. This also means that now viruses can be released much faster.

Basically replication means copying. The program must be able to copy itself somehow. The more a virus replicates itself the harder it is to handle.

In order to be classified a virus it must be capable of self-replication. This is the reason that Trojan horses are not true viruses, they do not self-replicate, and they rely on users to send them on. The virus must be able to spread. This is accomplished in a number of ways. Some viruses make copies of itself onto any available disk, others have the capability of scanning your email address book and sending itself off.

The activation of a virus is when the virus code or payload is activated. This will usually occur when certain criteria are met. The Jerusalem.Sunday.A, for example, was designed to delete any files activated on any Sunday past 1989, luckily the person who programmed this virus did a bad job and the virus does nothing but replicate.

This phase of the life cycle can actually occur before activation. In fact this is preferred. In this phase ICSA or a virus software company discovers and documents the virus. ICSA researchers take the time to examine the code and isolate it from valid code. Once isolated ICSA sends the isolated codes to the software companies for Assimilation.

Virus protection companies modify their software to include the new virus in their protection. This can take as little as one day after detection, up to six months later depending on the developer, the type of virus, and the complexity of the virus.

Resistance is futile all viruses will eventually be assimilated.

No virus has been completely eradicated, but many have ceased to be a major threat. The idea of this phase is that enough users have updated virus scanners installed that a virus will be deleted off of all infected systems eradicating the virus.

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