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Computer
Virus Close-up
By
S.K. Tsui
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A
computer virus is a program that is designed to replicate itself
by copying itself into the other programs stored in a computer.
There are several types of viruses. The FILE INFECTORS will attach
themselves to ordinary program files or document files. They usually
infect arbitrary .COM .EXE, .SYS, .OVL, .PRG, .MNU or document
files. The SYSTEM or BOOT-RECORD INFECTORS infect executable code
found in certain system areas such as the partition table of your
hard disk or the boot sector of your floppies. MACRO virus can
infect word processing and spreadsheet documents that use macros.
It is also possible for HTML documents containing JavaScript,
VB Script or other types of executable code to spread viruses
or other malicious code.
The damage
done depends on how the virus is written. Some may do little or
no damage, while some may completely destroy your files or render
your machine unusable.
Trojan horse
program is often confused with viruses. Actually it is not a virus
(because it does not attach itself to other programs), but pretends
to be a useful program such as a new release of famous application.
When you run it, it may delete files on your hard disk or do other
damage to your PC.
Ways of
Getting Infected
In order to
activate a virus, your computer has to execute the virus program
code by booting from an infected floppy, running an infected application,
or opening a program attached to an E-mail (or a Word document)
with macro embedded.
Will My
PC be Infected if I Read E-mail or Surf on the Internet?
In general,
reading a plain-text E-mail or HTML message will not infect your
computer with a virus. But you have to be very careful in handling
messages containing embedded executable code such as JavaScript
or VB Script in an HTML message or messages that include an executable
file attachment (i.e., a program file or a Word document containing
macros). If your mail client or browser has the ability to execute
this kind of executable code, then your computer may have a chance
to be infected by just reading or even previewing these kinds
of messages. VBS/BubbleBoy is the first e-mail worm of this type.
On the other
hand, it is safe to open files that the computer treats as pure
data. This includes opening graphics and sound files such as .gif,
.jpg, .mp3, .wav, and plain text files.
What to
Do if My PC Gets Infected
If a virus
does infect your PC, you can run the anti-virus program to remove
it. Simply follow the instructions of the anti-virus program.
If the virus destroys some of your data, you can restore these
files from your most recent backup. Remember to check the files
you restore to make sure these backups were not infected. If you
do not feel comfortable doing it yourself, ask a technical person
to do it for you.
General
Tips on Avoiding Virus Infections
