McAfee INTERNET SECURITY 5.0, Руководство пользователя

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Internet Security and Privacy
112 McAfee Internet Security 5.0
Computer Viruses and the Web
A computer virus is a small computer program that automatically replicates
itself and spreads from one computer to another. Viruses may infect
programs, your hard drive, and even some document files that employ
macros. Viruses do not infect data files, but they can create problems that
prevent you from accessing your data. Viruses are not accidents—they are
always created by computer programmers. PC viruses are similar to biological
viruses in that they:
n Are spread from host to host—the “host,” in this instance, is your PC.
n Are very good at reproducing themselves.
n
Can wreak havoc on an infected host system.
Biological viruses have proven to be tenacious— modern medicine’s success
in fighting viral infection has, so far, been rather limited. Fortunately, PC
viruses differ from biological viruses in that they are easier to combat, once
they are identified.
Are viruses really that dangerous?
Bear in mind that your chances of contracting a PC virus are slim, and even
more so, your chances of contracting a truly vicious virus. The scariest viruses
are malicious programs that intentionally corrupt or delete the data on your
PC. More benign viruses might simply display a message on your monitor or
make a strange sound, and then disappear. But even the most benign virus
occupies some disk space, and many remain in memory, which can cause your
PC to crash or behave erratically.
Types of Viruses
There are three main types of viruses:
n
File or program viruses
: A program virus attaches itself to a specific
program on your PC. Since many PC’s share certain files in common (for
example, the DOS program command.com, or the command “dir”),
which make these files tempting targets for virus programmers.
Program viruses are dormant until you run the associated program.
n Boot viruses (or Master Boot Record viruses) : The boot sector of a disk
is a physical location on the disk that contains information about the disk
and the files it contains. All disks and drives have a boot sector, even if
they aren’t “bootable.” A boot virus infects the boot sector of floppy
disks and hard drives, and are activated when you access or boot from
an afflicted disk.