What Is A Computer Virus?

Computer Virus: Introduction

A computer virus is a malicious program that is copied to your system without your consent. Depending on their severity, viruses can be categorized into three types—low-risk, medium-risk and high-risk viruses.

Low-risk viruses do not cause any severe damage to the PC, but they replicate quickly and display various text, audio, and video messages on the screen. They eat up a lot of system resources and drastically slow down your computer. These viruses may cause your PC to behave erratically and drastically deteriorate system performance leading to frequent system crashes and freezes.

Medium-risk viruses, usually carry buggy software with them that may generate frequent system errors and may also lead to data loss.

High-risk viruses are the ones that can do the most amount of damage to your PC. These malicious computer programs are designed to damage programs installed on your PC, delete your files and, in more severe cases, they may even format your hard disk, making you lose all your precious data.

All types of viruses add numerous malicious entries in the registry. These entries not only fill up the registry, but may also alter already existing registry entries to control the way programs work on your PC. For instance, file association for the EXE files may be changed in such a way that you may not be able to run any executable file on your computer. Thus, computer viruses generate several computer errors and may cause severe damage to your PC and data.

Virus Removal: Using Antivirus Utilities

There are many paid (Norton Antivirus and McAfee Antivirus) and free (AOL Free Active Shield and AVG Anti-Virus Free Edition) antivirus tools available today that you can use to prevent and remove virus infections from your PC.

Antivirus tools basically use two techniques to prevent and remove virus infections from your PC.

Virus Definition Approach

All files on your PC are examined for known viruses by matching them with a virus dictionary. If during the analysis, a file is found with a malicious code, the antivirus tool may take one of the following actions:

* Try to repair the file by removing the malicious code.
* Move the file to quarantine so the file cannot be accessed by other programs on your PC and stop it from spreading and replicating.
* Permanently delete the infected file from the system.

This method is quite effective and is used by all antivirus tools available today. However, because new viruses are released almost everyday, you need to regularly update your antivirus tools with the latest definitions to ensure that your computer is protected against the latest viruses.

Suspicious Behavior Approach

Suspicious behavior by any program is examined for possible malicious infections. The analysis is usually done by using methods such as data capture and port monitoring. This technique is generally useful in tracking new virus infections, which are still not there in the virus definitions. For instance, if a software program attempts to write some kind of data to another executable program, your antivirus tool may record it as a suspicious behavior. Once a suspicious behavior is detected, an alert is displayed to the user to ask what action to take.

Although useful, this method may display alerts for legitimate activities also. With frequent alerts being displayed, users may eventually start accepting all the messages and thus, make the whole process useless.

Virus Removal: Role of the Registry Cleaner

As discussed earlier, viruses add many entries within the registry. Some of these entries are added so deep within the registry that it may not be possible even for your antivirus tool to remove them. Therefore, the use of a registry cleaner tool is recommended. You can use this tool to perform a thorough scan of the registry and weed out any malicious entries left behind after the antivirus scan.

If your Windows XP or Windows Vista PC starts generating errors out of the blue, it is quite probable that your PC is infected by one or more viruses. In this case, to fix Windows XP and Windows Vista errors, you must get yourself a reliable antivirus software, update it with the latest definitions and scan your PC to identify virus files and delete them.