This document provides an introduction and overview of computer viruses. It defines computer viruses and explains how they work, discussing how viruses actively infect systems and spread. It categorizes common types of computer viruses such as macro viruses, memory resident viruses, overwrite viruses, and more. Specific virus names are listed as examples for each category. The document also discusses how to protect systems from computer viruses and describes some problems caused by viruses.

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The report about
(computer viruses)
By:Rawa Abdullah Taha
University of zakho
College of engineering
Mechanical department
Supervisor: Mr.Hassan
3-3-2019

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Abstract— In recent years the detection of computer viruses has become common
place. It appears that for the most part these viruses have been ‘benign’ or only
mildly destructive. However, whether or not computer viruses have the potential to
cause major and prolonged disruptions of computing environments is an open
question. In the below mentioned paper i have given the introduction about the
topic, definition, common viruses available and how to protect our system from
viruses.
Index Terms— computer security, virus, computer virus, worms, computer infection

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Table Of Contents
ABSTRACT
TABLE OF CONTENT
1 INTRODUCTION
2 DEFINITION OF COMPUTER VIRUSES
3 WHAT IS COMPUTER VIRUS
4 HOW VIRUSES ACTIVE
5 CATEGORIES OF COMPUTER VIRUSES
6 NAMES OF VIRUSES
7 HOW TO PROTECT OUR SYSTEM FROM COMPUTER VIRUS?
8 BEST ANTIVIRUS SOFTWARE.
9 PROBLEMS OF COMPUTER VIRUS
10 CONCLUSION
11 REFERENCE

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1 INTRODUCTION
in the mid 80’s ,the amjad brothers of Pakistan ran a computer store, they wrote the
first computer virus in the world, a boot sector virus that was called “Brain”, from
this discovery the revolution came to the computer industry, in recent decades the
term of computer viruses came into boom, even those who are not familiar with the
term of computer viruses become familiar with the term by seeing it in the
Hollywood movies with the latest technology. This paper purposes to depict the
current situation of computer viruses and the latest trend and the damage caused to
the system by the viruses.
2 DEFINITION OF COMPUTER VIRUSES
A computer virus is a program file that is capable enough to make its own code
without the knowledge of the user by linking the file to the document. When the file
or document that run destroys others files also and spread to the computer slowly
and steadily.
Computer viruses are just the same as the viruses or the diseases that attacks the
human body, they also directly or indirectly destroys our body the same case is that
with the computer viruses.
Execution of host program file results in execution of viruses.
Needs human action to execute. The structure of Computer Virus can be divided into
four phases-
1. Mark
2. Infection Mechanism
3. Trigger
4. Payload

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3 What is computer Virus
Computer viruses are small software programs that are designed to spread
from one computer to another and to interfere with computer operation.
A virus might corrupt or delete data on your computer, use your e-mail
program to spread itself to other computers, or even erase everything on
your hard disk.
Viruses are most easily spread by attachments in e-mail messages or instant
messaging messages. That is why it is essential that you never open e-mail
attachments unless you know who it's from and you are expecting it.
Viruses can be disguised as attachments of funny images, greeting cards, or audio
and video files.
Viruses also spread through downloads on the Internet. They can be hidden in illicit
software or other files or programs you might download.
To help avoid viruses, it's essential that you keep your computer current with the
latest updates and antivirus tools, stay informed about recent threats, and that you
follow a few basic rules when you surf the Internet, download files, and open
attachments.
Once a virus is on your computer, its type or the method it used to get there is not as
important as removing it and preventing further infection.
A computer virus is a computer program that can copy itself and infect a computer
without permission or knowledge of the user. The virus may also be purposly planted
in order to cause confusion. The original may modify the copies or the copies may
modify themselves, as occurs in a metamorphic virus. A virus can only spread from
one computer to another when its host is taken to the uninfected computer, for
instance by a user sending it over a network or carrying it on a removable medium
such as a floppy disk, CD, or USB drive. Additionally, viruses can spread to other
computers by infecting files on a network file system or a file system that is accessed
by another computer. Viruses are sometimes confused with computer worms and
Trojan horses. A worm, however, can spread itself to other computers without
needing to be transferred as part of a host. A Trojan horse is a file that appears
harmless until executed. In contrast to viruses, Trojan horses do not insert their code
into other computer files. Many personal computers are now connected to the
Internet and to local-area networks, facilitating their spread. Today's viruses may also

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take advantage of network services such as the World Wide Web, e-mail, and
file sharing systems to spread, blurring the line between viruses and worms.
Furthermore, some sources use an alternative terminology in which a virus is any
form of self-replicating malware. The term comes from the term virus in biology. A
computer virus reproduces by making, possibly modified, copies of itself in the
computer's memory, storage, or over a network. This is similar to the way a biological
virus works.
Some viruses are programmed to damage the computer by damaging programs,
deleting files, or reformatting the hard disk. Others are not designed to do any
damage, but simply replicate themselves and perhaps make their presence known by
presenting text, video, or audio messages. Even these benign viruses can create
problems for the computer user. They typically take up computer memory used by
legitimate programs. As a result, they often cause erratic behavior and can result in
system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to
system crashes and data loss.
There are many viruses operating in the general Internet today, and new ones are
discovered every day.
3.1 What a computer virus do?
 A virus tries to take control of computer system it has infected at the first
opportunity availible.it makes copies of itself and also try to carry harmful task
written in its program. This process can happen so quickly that the user is not even
aware of the presence of a virus in his/her computer.

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4 How Viruses Active
We are always afraid that viruses do something harmful to files when they get active,
but not all the viruses activate. Some viruses just spread out, but when viruses
activate they do very different things. Might play a part of melody or play music in
the background, show a picture or animated picture, show text, format hard disk or
do changes to files.
As an example, in one unnamed company: over a long period of time, the files in a
server were corrupted just a bit. So backup copies were taken from the corrupted
files.
And after they noticed that something was wrong, it was too late to get back the data
from the backups. That kind of event is the worst that can happen for the uses.
There is also talk that viruses have done something to hardware like hard disk or
monitor. Viruses can not do any harm to hardware but they can do harm to programs
and for example to BIOS so that computer does not start after that. Usually you can
start the computer from a boot diskette if the computer does not start otherwise.

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5 CATEGORIES OF COMPUTER VIRUSES
There are following basic categories of viruses-
5.1 Macro Viruses
These viruses infects all the files that contain macros i.e.doc,pps,xls and mdb, they
affect the macros ,templates and also the documents that are present in the files.
Examples are:
• Relax
• bablas
• Melissa.A
• 097M/Y2K
5.2 Memory Resident Viruses
They attack inside the computer memory, it gets activated when the operating is
running and infects all other files, they are hidden in RAM.
Example are:
• CMJ
• meve
• randex
• mrklunky
5.3 Overwrite Viruses
These viruses delete the efficient information available in a file,at the end it leaves
the file fully or half useless,it replaces the content but do not change the size of the
file.
Examples are:

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• Trj.Reboot
• way
• trivial.88.D
5.4 Direct Action Viruses
These types of virus duplicates and takes action when they are executed, they infect
the files in the directory or the folder in it . AUTOEXEC.BAT, they are found in the root
directory.
Example : Vienna virus
5.5 Directory Virus
Other name for this type of virus is cluster virus,they infect the directory of computer
it does this by changing the path of file location,located in the disk but after affecting
it affects the entire directory.
Example is: dir-2 virus
5.6 Web Scripting Virus
Mostly the web pages include complex codes with the purpose to create an
interactive and interesting content, these codes are used to create unwanted actions,
they comes from infected WebPages.
Example is: JS.Fortnight – a virus that spreads via malicious emails.
5.7 FAT Viruses
They attack the file allocation table (FAT) which is the part to store every
information.
Examples is: the link virus

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Polymorphic Virus
They do their own encrypting and programming in different
style when they infect the computer, they use different encryption and algorithms, it
makes it difficult for the antivirus to trace it.
Examples are:
• Marburg
• tuareg
• Satan bug
• elkern
5.8 Worm
This program has the property of self replication causing negative effects on the
computer. Worm Viruses Include:
• lovgate.F
• sobig.D
• trile. C
• PSWBugbear.B
• Mapson
5.9 Trojans
Trojans can un approved tracing of important login details of users online..Email
Virus. This is a virus spread through an email.This virus hide in an email and when the
receiver receives the mail it is spread widely.

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6 NAMES OF VIRUSES
There are a number of popular viruses-
6.1 ILOVEYOU
The ILOVEYOU virus is considered one of the most dangerous computer virus ever
created. The virus was created by two Filipino programmers, Reonel Ramones and
Onel de Guzman. It made use of social engineering to get users to click on the
attachment; the attachment was basically a txt file This led to the execution of the E-
Commerce Law.
6.2 Code Red
Code Red was discovered in 2001 by two eEye Digital Security employee, it set it goal
on computers with Microsoft IIS web server.
6.3 Sasser
It is basically a windows virus created by Sven Jaschan, who also created the Netsky
worm; it took advantage of buffer overflow weakness in local Security authority
service
6.4 Zeus
It is a Trojan horse made to affect Windows computer to perform various criminal
tasks, common task in this is the main in the middle browser key logging and form
grabbing.

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S
N
Name of the
virus
Year of
discovery
Infection caused
1 iloveyou 5 may 2000
It spread by e-mail, arriving
with the subject line "ILO VEYOU"
and an attachment, "LOVE-LETTER
FOR-YOU.txt.vbs".
2 Code red July 15,2001
It allows the worm to execute
arbitrary code and the machine
with worm
3 Sasser April 12,2004
The virus scans different
ranges of IP address and
connects victims computer
primarily through TCP
4 Zeus July 2007
It is spread mainly through
drive by downloads
5 mocmex 17 February 2008
It was the virus that at
tacked the photo frame
6
Daprosy
worm
15 july 2009
It stealed online game
passwords.
7
Waledac
botnet
January,2010
It was capacable of sending
about 1.5 million spam mes
sage
8 duqu 1 september,2011
Its nature was same as that
of the malware.
9 shamoon
16
aug,201
2
It is designed to target com
puters running on Microsoft
windows in the energy sec
tor
10 Cryptolocker
Sep
tember
2013
It encryptes the files on a
user’s hard disk
11 Regin
No
vember
2014
Once downloaded,regin quietly
downloaded extension of itself,
makes difficult
to be detected
12 ramsowore 2016 Used for defence purposes.

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7 HOW TO PROTECT OUR SYSTEM FROM COMPUTER
VIRUS?
1. Keep your windows defender activated as it could protect the system from any
malicious activity occurring.
2. use antimalware app and also keep it updated(basically antimalware app check for
viruses, spyware and any other threatening events occurring within the system which
could interrupt its processing)
3. use of pop-up blocker is useful
4. we should pay attention to all the notification.
5. if we are using Internet Explorer we should ensure that Smart screen is turned on
6. windows should be updated and it should be the genuine windows
7. make sure that User account is always turned on.

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8 Best antivirus software.
Norton antivirus
 Norton antivirus is a product of Symantec corporation.
Founded in 1982.
 Notion check the following program
• Boot record s
• Programs(at the time you used them)
• All local hard drives,
• Files download from internet,
• Usb(when in use)
MacAfee virus scan
MacAfee, Inc. is an antivirus software and computer security
company headquartered in Santa Clara, California. It markets
McAfee Virus Scan and related security products and
services, including the Intercept, and Found stone brands. ...
Kaspersky ANTIVIRUS
 Kaspersky is product of Kaspersky lab,
 A Russian computer security company,
• Co-founded by Natalya Kaspersky antivirus, do the
following things
• Invites virus scan by opening the Kaspersky antivirus
window.
9 PROBLEMS OF COMPUTER VIRUS
There are many problems associated with computer viruses some are listed below
1. Computer speed or performance, decreases
2. Computer boots and reboots again and again
3. loosing of data from drives and disks
4. Cause erratic screen behavior.
5. Weird messages comes on screen

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6. Browser home page also changes itself.
7. Application softwares changes
10 CONCLUSION
Virus basically destroys our system due to which our efficient information is also lost
and multiple copies of the same data is stored due to which more pressure is put on
the computer, so we should always keep our firewall and antivirus updated.
There are lots of viruses in the world and new viruses are coming up every day. There
are new anti-virus programs and techniques developed too. It is good to be aware of
viruses and other malware and it is cheaper to protect you environment from them
rather then being sorry. There might be a virus in your computer if it starts acting
differently. There is no reason to panic if the computer virus is found. It is good to be
a little suspicious of malware when you surf in the Internet and download files. Some
files that look interesting might hide a malware. A computer virus is a program that
reproduces itself and its mission is to spread out. Most viruses are harmless and
some viruses might cause random damage to data files.
Some people want to experiment how to write viruses and test their programming
talent. At the same time they do not understand about the consequences for other
people or they simply do not care.
Viruses mission is to hop from program to other and this can happen via floppy disks,
Internet FTP sites, newsgroups and via email attachments. Viruses are mostly written
for PC-computers and DOS environments.
Viruses are not any more something that just programmers and computer specialist
have to deal with. Today everyday users have to deal with viruses.
11 References
[1] A System to Support the Analysis of Antivirus Products’ Virus
Detection Capabilities, Marko Helenius, 2002.
[2] http://www.faqs.org/faqs/computer-virus/
[3] http://www.wildlist.org/WildList/

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