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Computer Viruses and Other Malware
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Computer Viruses and Other Malware
Today, people rely on computers to create, store, and manage critical information. Thus, it is
crucial users take measures to protect their computers and data from loss or damage, especially
for information that is transmitted over networks. Every unprotected computer is susceptible to a
computer virus, worm, Trojan horse, and/or rootkit.
• A computer virus is a potentially damaging computer program that affects, or infects, a
computer negatively by altering the way the computer works without the user’s knowledge or
permission. Once the virus infects the computer, it can spread throughout and may damage
files and system software, including the operating system.
• A worm is a program that copies itself repeatedly, for example in memory or on a network,
using up resources and possibly shutting down the computer or network.
A Trojan horse (named after the Greek myth) is a program that hides within or looks like
a legitimate program. A certain condition or action usually triggers the Trojan horse. Unlike a
virus or worm, a Trojan horse does not replicate itself to other computers.
• A rootkit is a program that hides in a computer and allows someone from a remote location
to take full control of the computer. Once the rootkit is installed, the rootkit author can
execute programs, change settings, monitor activity, and access files on the remote computer.
Computer viruses, worms, Trojan horses, and rootkits are classified as malware (short for
malicious software), which are programs that act without a user’s knowledge and deliberately alter
the computer’s operations. Users can take several precautions to protect their home and work
computers and mobile devices from these malicious infections. For example, users should install
an antivirus program and update it frequently. An antivirus program protects a computer against
viruses by identifying and removing any computer viruses found in memory, on storage media, or
on incoming files. Most antivirus programs also protect against other malware. When you purchase
a new computer, it often includes antivirus software. The list in Figure 42 summarizes important
tips for protecting your computer from viruses and other malware.
Tips for Preventing Viruses and Other Malware
1. Never start a computer with removable media inserted in the drives or plugged in the ports, unless the media are uninfected.
2. Never open an e-mail attachment unless you are expecting it and it is from a trusted source.
3. Set the macro security in programs so that you can enable or disable macros. Enable macros only if the document is from a trusted source
and you are expecting it.
4. Install an antivirus program on all of your computers. Update the software and the virus signature files regularly.
5. Scan all downloaded programs for viruses and other malware.
6. If the antivirus program flags an e-mail attachment as infected, delete or quarantine the attachment immediately.
7. Before using any removable media, scan the media for malware. Follow this procedure even for shrink-wrapped software from major
developers. Some commercial software has been infected and distributed to unsuspecting users.
8. Install a personal firewall program.
9. Stay informed about new virus alerts and virus hoaxes.
Figure 42
With the growing number of new viruses and other malware, it is crucial that users take steps to protect their
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