| Avoiding A Computer Virus |
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| Index |
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| What is
a Computer Virus? |
| A Virus is a program that infects executable
files. When the infected file is executed, the virus replicates
itself and spreads by infecting other executable files. Of course,
the virus will try to infect your computer without your knowledge
or permission. A virus generally has two phases; (1) an infection
phase where the virus reproduces extensively, and (2) an attack
phase where it does the damage it was programmed to do. |
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| What types
of files can spread viruses? |
| Viruses can infect any type of executable files
(e.g. flies with extensions like "EXE", "COM", "VBS", "BAT"
"SCR"). "Macro" viruses infect word processing and spreadsheet
documents that use macros (e.g. DOC & XLS.) Files that are treated
as pure data are safe from viruses. These include graphics,
sound and plain text files (e.g. JPG, GIF, MP3, WAV & TXT files.)
Beware of files with multiple extensions such as "help.txt.exe".
Only the last extension counts. Trojan Horse programs often
disguise themselves this way. By default, Windows hides the
extension of files. You can turn off this feature, or you can
right click on the file and choose properties. The properties
dialog box will show you the true file type and extension (MS-DOS
name.) Its important to note that viruses will have no effect
if the file they have infected is not executed. |
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| How are viruses
spread? |
 A
virus' aim is usually to multiply and infect as many files as
possible, and then unleash an attack of some sort. When an infected
program is executed, the virus multiplies and infects other
programs on its host computer or other connected computers on
a network. Boot sector viruses can infect the boot sector of
hard drives and floppy disk. The virus spreads if another computer
is booted from the infected floppy disk. Viruses can be downloaded
from the Internet hidden in downloaded programs or distributed
in chat rooms when people share files. Viruses are also distributed
in email. |
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| What do
viruses do to computers? |
| Some virus can cause serious damage while some
are not very harmful at all. Viruses can delete files, corrupt
data, slow down your computer or cause typos in word processing
documents. Less harmful viruses may play annoying music or create
animations and messages on your screen. Viruses cannot physically
destroy your computer's components. |
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