Monday,
August 25, 2003 |
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Feature |
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The dirty half-dozen
Gurpreet S Arora
A
VIRUS is a program that reproduces its own code by attaching itself to
another program. It is basically a self-replicating program written for
destructive purpose. It interferes with the computer’s operating
system (the basic software that runs the computer). Viruses are designed
to replicate and elude detection. Like any other computer program, a
virus must be executed to function — that is, it must be loaded from
the computer’s memory, and the computer must then follow the virus’
instructions. These instructions are called the payload of the virus.
The payload may disrupt or change data files, display a message, or
cause the operating system to malfunction. It is made in such a way that
it enters computer without the knowledge of machine or its user.
The idea of virus started
with the possibility of writing self-replicating software. The idea was
first put forward by Hungarian American mathematician John von Neumann
at the Institute for Advance Study in Princeton, New Jersey.
There are six categories
of virus — parasitic, bootstrap sector, multipartite, companion, link,
and data file. Parasitic virus infects executable files or programs in
the computer. They leave the contents of the host program unchanged but
append to the host in such a way that the virus code is run first.
Bootstrap sector virus reside on the first portion of the hard disk or
floppy disk, known as the boot sector, and replace either the programs
that store information about the disk’s contents or the programs that
start the computer. Multipartite viruses combine the abilities of the
parasitic and the bootstrap sector viruses, infecting either files or
boot sectors. A companion virus does not modify a file. Instead it
creates a new program with the same name as a legitimate program and
tricks the operating system into running it. Link viruses modify the way
the operating system finds a program, tricking it into first running the
virus and then the desired program. The entire directories (sections) on
a computer can be infected by a link virus, and any executable program
accessed within that directory will trigger the virus. Other viruses
infect programs that contain powerful macro languages (programming
languages that let the user create new features and utilities), which
can open, manipulate, and close data files. These viruses, called data
file viruses, are written in macro languages and automatically execute
when the legitimate program is opened.
Viruses that left
their mark
1) April 26
2) Friday 13th
3) Christmas
4) I love you
5) Melissa
6) Win97M.Gesture B
7) W32.Pixo
8) VBS.Loveletter.F
9) W32.NewApt.Worm
10) UA1.Trogan
Computer
virus spread when the infected executable code - that run programs are
exchanged from one computer to another. It can be through infected
floppy or CD or through infected e-mail. Through these mediums, the
virus copies itself to the other computer without the knowledge of the
user. A virus upon entering a system first monitors the system and then
activates itself at a proper time to cause maximum harm to the
information stored on to the computer.
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