One of the biggest fears of having computers are viruses, viruses
are malicious programs designed entirely for destruction and havoc.
Viruses are created by people who either know a lot about programming
or know a lot about computers.
Once the virus is made it will generally be distributed through
shareware, pirated software, e-mail or other various ways of transporting
data, once the virus infects someone's computer it will either start
infecting other data, destroying data, overwriting data, or corrupting
The reason that these programs are called viruses is because it
is spreads like a human virus, once you have become infected either
by downloading something off of the Internet or sharing software
any disks or write able media that you placed into the computer
will then be infected. When that disk is put into another computer
their computer is then infected, and then if that person puts files
on the Internet and hundreds of people download that file they are
all infected and then the process continues infecting thousands
if not millions of people.
HOW VIRUSES MAY EFFECT FILES
VIRUSES can effect any files however usually attack .com, .exe,
.sys, .bin, .pif or any data files. Viruses have the capability
of infecting any file however will generally infect executable files
or data files such as word or excel documents which are open frequently.
It can increase the files size, however this can be hidden. When
infecting files virtues will generally increase the size of the
file however with more sophisticated viruses these changes can be
It can delete files as the file is ran. Because most files are
loaded into memory and then ran once the program is in memory the
Virus can delete the file.
It can corrupt files randomly. Some destructive viruses are not
designed to destroy random data but instead randomly delete or corrupt
It can cause write protect errors when executing .exe files from
a write protected disk. Viruses may need to write themselves to
files which are executed because of this if a diskette is write
protected you may receive a write protection error.
It can convert .exe files to .com files. Viruses may use a separate
file to run the program and rename the original file to another
extension so the exe is ran before the com.
It can reboot the computer when a files is ran. Various computers
may be designed to reboot the computer when ran.
The most commonly used method of protecting against and detecting
viruses is to purchase a third party application designed to scan
for all types of viruses. Examples are Nortons Antivirus, McAfee,
Kaspersky AV, and PC-cillan though many more are available.
Alternatively a user can look at various aspects of the computer
and detect possible signs indicating a virus is on the computer.
While this method can be used to determine some viruses it cannot
clean or determine the exact virus you may or may not have.
If you have Windows95 / Windows 98 you can click on start, settings,
control panel, system, and under system go to performance and determine
if the file system is 32-bit. If the file system is running in MS-DOS
compatibility mode check the box indicating what is running in MS-DOS
compatibility mode to determine if the master boot record has been
modified. If the Master boot record has been modified its a good
possibility that you may have a virus on the computer.
Another method is to check fdisk. In fdisk choose four to display
the partition information if you have multiple partitions such which
have scrambled text such as % or strange characters this can be
another indication of a virus on the computer.