The most enduring and frightening characteristic of a computer virus is the fact that it is capable of reproducing on its own and transmitting to other computer systems, so that it can spread the infection. In writing the virus, programmers come up with a series of malicious code, which is meant to interrupt the normal functioning of any given system.

There are viruses that are latent whilst others are quite active. Essentially, the user will find that their system has been corrupted and that their data is no longer what it used to be.

An Impediment to System Performance

For the user, the first sign that they are affected by a virus is when they are unable to use their PC in the way that they are used to. The medium of distribution for viruses is diverse. It includes USB drives, CDs, DVDs, email, downloads and virtually all types of media. They are considered to be part of a larger class of malware that includes worms and Trojans.

However, viruses are distinguished from spyware and adware because these two do not have the ability to replicate themselves. Nevertheless, users are often bothered by the notion that someone is watching their every move online or that they are subject to uncontrolled and surreptitious advertising.

The virus will try to attach itself to an executable file within the structure of the host computer. That essentially means that when you open the file, the virus is also loaded. It then goes into the computer memory and begins the work of dismantling the system. Once it is in the memory, the virus will be free to infect as many files as possible.

The latest viruses are designed in such a clever way, that they are able to avoid detection by using polymorphic code. This means that the viruses modify its decryption module. In effect, the new infection comes with a slightly different version of the virus, so that the antivirus software is left confused.

Vulnerabilities for Software Producers

The favorite victim for virus creators are those companies that are responsible for developing new software packages. This is because they indirectly provide a conduit for the virus to spread. This is particularly true, if the software is prone to bugs. The programmers often create bait files in order to be able to capture the virus and see how it operates in real life.

All users as a matter of fact should have a good antivirus program. Norton and Avira have been leading names in the industry, but there are many more others that are coming to the fore.

Spectrum of Virus Activities

There is a lot of damage that viruses can do. This includes deleting or altering files; slowing down internet connections; destroying hardware; compromising important financial data such as usernames and passwords. They can also make certain disks unreadable. The worst viruses are able to take over the system, so that it seems as if the computer is being controlled from a remote location. This in turn creates very many security issues.