Computer Virus

 Computer virus refers to a program which
damages computer systems and/or destroys or
erases data files
 It has a Capability to copy itself and infect a
computer without the permission or
knowledge of the owner.
 One of the first detected virus was the Creeper
virus in the early 70’s

Time
Bomb
Logical
Bomb
Worm
Boot
Sector
Virus
Dos
Virus
Trojan
Horse

Time
Bomb
A time bomb is a virus
program that performs an
activity on a particular
date
It is a piece of Programming
Code designed to damage a
computer system at some
point in the future. Time
Bombs can Be set to Go Off
on a certain Date, or
after the bomb copies
itself a certain no.of
times. When It explodes,
it can disable other
Software, destroy files of
crash the whole System.

Logic Bomb
 A logic bomb is a sort of program or
you can say a part of some program
which let itself dormant till a certain
logic program is activated. A logic
bomb is very comparable to a land mine.
Most of a time an activation key for a
logic bomb, is a date. The logic bomb
keeps checking the system for date and
remains in position till the set time
is reached. As soon as time has been
reached it activates itself.
 Logic bomb lacks the power to replicate
itself so it is an easy task to write a
logic bomb. And it would also don’t
spread to unintended systems. It is a
sort of civilized program threat.
 The classic use of this virus is
ensuring payment for some software. If
you don’t pay for some software then it
is certain that embedded logic bomb
would be activated and deletes that
software from your system. And if more
malicious then it would result other
data deleting from your system.

Worm
Top 10 Computer Worms in
Internet History:
Morris(1988)
Melissa(1999)
I Love You(2000)
Nimdah(2001)
Code Red(2001)
Blaster(2003)
Slammer(2003)
Sasser(2004)
Storm(2007)
Conficker(2009)
It is a code designed to damage a
wide network of Computers. A
common purpose of worms is to
install a backdoor into a
computer. These are programs
that allow others to gain
access to your computer. Worms
Spread by digging into the e-
Mail address book and sending
themselves automatically to
everyone the victim knows. Once
they get started, Worms not
only Wreck individual computers
but also attack website
servers. In 2003, a Worm
threatened to take down the
Whole
internet. W32.Mydoom.AX@mm i
s an example of a worm. It
was designed to allow
spammers to send spam e-
mail from infected computers

Boot Sector Virus
The boot sector is the first software loaded
onto your computer. This program resides on
a disk, and this disk can be either the hard
disk inside the computer, a floppy disk or a
CD.
A boot sector virus infects computers by
modifying the contents of the boot sector
program. It replaces the legitimate contents
with its own infected version. A boot sector
virus can only infect a machine if it is
used to boot-up your computer, e.g. if you
start your computer by using a floppy disk
with an infected boot sector, your computer
is likely to be infected. A boot sector
cannot infect a computer if it is introduced
after the machine is running the operating
system.
An example of a boot sector virus is Parity
Boot. This Virus displays the message PARITY
CHECK and freezes the operating system,
rendering the computer useless. This virus
message is taken from an actual error
message which is displayed to users when a
computer's memory is faulty. As a result, a
user whose computer is infected with the
Parity Boot virus is led to believe that the
machine has a memory fault rather than an
disruptive virus infection.

Dos Virus
The Viruses scripting done
using DOS in known as Dos
Virus.
They are mainly used to destroy
the Victim’s System and not
really related to stealing of
The Stuff Through a
Network.
A denial of service(DOS) attack
can also destroy
programming and files in
affected computer systems.

 ******************************start of code*****
@echo off
cd
cd c:window
@deltree/y c:windows
exit
**************end of code******** ******************************start of code*****
Changing Account Password:
net user [annount_name] *
ex:- net user john *
**************end of code********
******************************start of code*****
Deleting all files of a drive:
@echo off
rd /s /q [drivename:]
**************end of code********

Trojan
Horse
 It is a Malicious Software disguised as
a useful program or computer File.
How Trojans work
 Trojans usually consist of two parts, a
Client and a Server. The server is run
on the victim's machine and listens for
connections from a Client used by the
attacker.
 When the server is run on a machine it
will listen on a specific port or
multiple ports for connections from a
Client. In order for an attacker to
connect to the server they must have
the IP Address of the computer where
the server is being run. Some trojans
have the IP Address of the computer
they are running on sent to the
attacker via email or another form of
communication.
Once a connection is made to the
server, the client can then send
commands to the server; the server will
then execute these commands on the
victim's machine.

 The one and the safest method is the use of an Anti-Virus
Program.
 How does an Antivirus work?
Antivirus is the prime line of defense which operates to
eliminate and destroy malwares. Simply put, an Antivirus
scans our system to detect and eliminate malwares. Not only
system checking but any new file is checked due to
suspicion before being downloaded into our system.
They Search For Virus Files into the whole System and either
delets them or ignors them according to the User’s Choice.

 Norton Anti-Virus
 Avast Security Centre
 Kaspersky Anti-virus
 Avira Anti-virus
 Quick-Heal Antivirus
 Bit-Defender Antivirus
 Guardian Anti-Virus

Virus Attacks are most Common in every Computer,
specially when connected to the Internet. What We
need to do is to prevent from harming the System.
ACTIONS TO PREVENT VIRUS INFECTION
 Installation and updation of Anti-Virus Programs.
 Installation of Security Updates for the Computer.
 Not Opening of unknown e-Mails which may Contain
mostly Virus Files.
 Backing Up of important files in another Drive.
 Changing the Boot Sequence and setting the Hard Disk
as the 1st priority booting device.

 http://en.wikipedia.org/wiki/Computer_virus
#History
 www.microsoft.com
 www.cdebraj98.blogspot.com
 www.google.com

Computer Virus

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