A computer virus can put you out of business quick. If your computer is infected by a virus, you can't do too much to combat these hideous files and protect your system. So you need to focus on prevention! In this section, you'll learn the following:
What a virus is and why they're dangerous
How a virus can be transmitted to your system and how you can transmit them to others
The advantages of using virus-scanning software
How to disinfect your system once you catch a virus
Chapter 2 introduced you to viruses. In this chapter, we show you how to use special software to protect your system from viruses.
What Is a Virus?
Know what a virus is and what the effects of a virus might be.
Technically, a virus is a file that replicates itself. But most computer viruses also have other effects. They might delete files on your hard drive, hijack your Internet connection, or cause programs to stop working. Some viruses send email from your account to spread themselves. Others install "back doors" on your computer, so that malicious users can control your computer remotely. Viruses are destructive, and you should avoid them at all costs.
Transmitting a Virus
Understand some of the ways a virus can be transmitted onto a computer.
By and large, most viruses are transmitted by infected email messages that lull the user into opening an attachment that then releases the file into the system. Most of the time, you can avoid infection by not opening attachments from strangers. If someone you know is infected, their system might send you an infected message; therefore, it's important to carefully review all email messages with attachments, even when you know the sender. If you weren't expecting the attachment, contact the person before actually opening the attached file.
Email isn't the only means by which you can be infected or infect others. Visiting a Web site or using an infected diskette can infect your system.
Protecting Your System
Understand the advantages of a virus-scanning application.
Regardless of how careful you are, you can become infected with a virus. The best way to protect yourself is with special software. There are a number of software programs, known as virus-scanning applications, on the market that are designed to scan your incoming email and your system for viruses. When a virus is found, the software deals with it before it can infect your system.
Applying the Disinfectant
Understand what "disinfecting" files means.
Once your scanning software detects a file that's been infected, you can try to disinfect the file. That means the software will try to remove the virus without harming the file, and sometimes it works. Often, it doesn't. In that case, the file should be quarantined or deleted. A quarantined file is moved to a safe location within your system. Deleting the file is probably the best course of action because a quarantined file can still release its virus.
As we mentioned, viruses are dangerous and the best protection is special scanning software. In the next section, we walk you through the process of using software to scan for infected files.
Scanning for Viruses
Use a virus-scanning application to scan specific drives, folders, and files.
Most virus-scanning software is enabled all the time. That way, it can check for infected files every time you download email.
On a regular basis, you'll also want to check your system, just to make sure it's clean. An undetected virus could be causing problems you don't yet know about. At the very least, it is a ticking time bomb. Run scans often by launching your virus-scanning software and choosing the appropriate scan options. Figure 3.37 shows the scanning options provided by Norton AntiVirus. (Remember, your software might present options differently, but most software will offer the same type of protection.)
Figure 3.37 Scan your system's files for viruses.
The Importance of Regular Updates
Understand why virus-scanning software needs to be updated regularly.
Malicious developers are releasing new viruses that attack vulnerable systems every day. To be truly effective, the scanning software must be current. That means you'll probably need to download new virus-detecting files on a regular basis. If you receive a lot of email or browse a lot of Web sites, every few days isn't too often.