Viruses and Antivirus Programs
In general, a virus is a computer program intentionally designed to cause harm to your computer. Like their biological namesakes, viruses also replicate themselves. Viruses may rename files so they are unusable, delete files, replicate themselves through an e-mail program or other application, or simply tie up valuable computer resources such as CPU and RAM by attacking those resources. Viruses do not generally bring down a system though. Viruses most often cause system-wide slow downs, produce annoying pop-up messages, and cause nagging error messages.
The most common type of virus is one that attaches to an executable file, such as Outlook, Excel, or a graphic-editing program. Most of these types of viruses, once on your computer, simply wait for you to perform the command necessary to release them, such as opening a ZIP file, running a macro, or opening an e-mail attachment. Once they are running, they replicate themselves using your computer and its resources. These types of viruses are usually called program viruses.
Other common virus types are those considered malware. These viruses may run during boot-up, when logging on to a network, or even when a specific hour and minute of the day is reached. For example, in the latter case the malware may release automatically when the system clock hits midnight of a certain year, say 2010. It may then delete all JPEG files or all documents on the computer, or create a pop-up that simply says "Happy New Year!" Spyware and adware are also considered malware, as detailed in a sidebar later in this tutorial.
How a Virus Works
There are plenty of virus types, but they all generally work the same way. First, the virus gets onto your computer. This usually happens without your knowledge, although you are usually at fault for contracting it. Most of the time, the viruses are acquired through malicious software you intentionally download or open, such as trial software, screen savers, e-mail attachments, or freeware.
Once on the computer, they run. Viruses are executable files and run when you install the screensaver, trial software, or freeware, or when you open an e-mail attachment that contains it. Once the virus is loose, it produces symptoms and begins to replicate itself. As noted, these symptoms can range from harmless pop-up messages to the deletion of important files. Some viruses wait in the background too, in anticipation of an event such as a specific date and time.
No matter what, viruses replicate. That is why it is so important to have antivirus software configured on your computer. This software should catch a virus before it is opened, thus preventing it from doing harm and replicating to other computers on your network (or the Internet).
You can prevent the majority of viruses by being vigilant about what you download, install, and open. If you get e-mail with an attachment from someone you don't recognize, do not open the attachment. Even if you do recognize the sender, e-mail back and ask them if they meant to send you an executable file. If you are on a Web site and you are prompted to download and install a program, do not do it. Finally, do not fall for free screensavers, free emoticons, or free software of any kind on the Internet, unless you have read the reviews and license and know it is a legitimate and virus-free application.
Custom-Configure Antivirus Programs
Antivirus software, while an excellent and must-have tool, can sometimes cause your computer to perform more slowly than a mild virus would. Letting your antivirus program check for updates daily is important, checking updates when you are logging on to the Internet, will slow down access and quickly become tedious. Configuring your antivirus software perform a system-wide virus scan at boot up is also a performance killer. Imagine the issues you'd have if you let your computer perform a two-hour scan just when you are sitting down in the morning to get some work done. The point of this section then is to learn how to use and configure your antivirus programs for the best performance possible, while at the same time protecting you and your computer from harm.
The newest antivirus programs offer more than just protection from viruses. Many also contain firewalls, privacy services, and options for permanently deleting files. You will need to work with those accordingly.
To see what your antivirus software offers, click Start> All Programs, and select your antivirus program from the list (For example you installed McAfee antivirus.) There are four options: McAfee VirusScan, McAfee Personal Firewall Plus, McAfee Privacy Service, and McAfee Shredder. Each of these offers different kinds of protection. You may have these or others.
Spend some time now and open each antivirus subprogram you have to see what is offered. Only then can you configure the program for the best possible performance. You should look for several things. If possible, set or use your antivirus program to perform the following tasks:
- Schedule a complete system scan weekly, during a time when the computer is on but is not in use.
- Check for quarantined files twice a month and either delete files you know are harmful or restore files that are not.
- Find out what viruses are currently circling the Internet by visiting your antivirus manufacturer's Web site as time allows.
- Run only one antivirus program. Running more than one can cause system instability.
- Scan incoming and outgoing e-mail automatically.
- Start when Windows starts.
- Create a rescue disk in case a virus disables your computer.
- Schedule updates to download and install at a time that is convenient for you, a time when you will not be actively using the computer or using programs that require a lot of computer resources.
- Use the firewall to warn you of potential dangers, but not automatically block them. You can then decide for yourself what is or is not a potential danger and take the appropriate action.
- Enable instant messaging protection.
- Perform a manual scan anytime you see anything suspicious, such as an odd or recurring pop-up message, changes to names of files or pictures, or a noticeable slowdown at the computer (which would indicate an attack on computer resources).