Computer viruses are small programs that spread from one computer to another and interfere with operations. They are deliberately created by programmers or virus creation software. Viruses enter computers through email attachments, downloads, or infected files on removable drives. Symptoms of viruses include programs taking longer to load, changing file sizes or drive lights flashing unexpectedly. Common types are Trojan horses, worms, and boot sector viruses. Users can avoid viruses by only opening trusted email attachments, backing up files, and using updated antivirus software.

1. Presented by:
Bennette Osae Addo.
ICT Teacher-GCIHS
COMPUTER VIRUS

3. What are Computer Viruses
Computer Viruses are small
software programs that are
designed to spread from one
computer to another and to
interfere with computer
operation.

4. Why people create computer
viruses
 Computer viruses do not come into existence
spontaneously. They are deliberately created
by programmers, or by people who use virus
creation software.
Virus writers can have various reasons for creating and
spreading malware. Viruses have been written as
research projects, pranks, to attack the products of
specific companies, to distribute political messages, and
financial gain from identity theft, spyware, and cryptoviral
extortion. Some virus writers consider their creations to be
works of art, and see virus writing as a creative hobby.

5. Ways computer viruses enter your computer
 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.


6. How to detect virus?
Some Symptoms
q Program takes longer to load.
q The program size keeps changing.
q The drive light keeps flashing when you are
not doing anything.
q User created files have strange names.
q The computer doesn't remember CMOS
settings.

7. Examples of computer viruses
 Trojan Horse:
A destructive program that
masquerades as a benign
application. Unlike viruses, Trojan
horses do not replicate themselves
but they can be just as destructive.

One of the most insidious types of
Trojan horse is a program that claims
to rid your computer of viruses but
instead introduces viruses onto your
computer.


8.  Worm:
A worm is similar to a virus by its design,
and is considered to be a sub-class of a
virus. Worms spread from computer to
computer, but unlike a virus, it has the
capability to travel without any help from
a person. A worm takes advantage of file
or information transport features on your
system, which allows it to travel unaided.
 The biggest danger with a worm is its
capability to replicate itself on your
system, so rather than your computer
sending out a single worm, it could send
out hundreds or thousands of copies of
itself, creating a huge devastating effect.

9.  Boot sector Virus :
A virus which attaches itself to the first part
of the hard disk that is read by the
computer upon boot up. These are
normally spread by floppy disks.
Macro Virus:
Macro viruses are viruses that use another
application's macro programming
language to distribute themselves. They
infect documents such as MS Word or MS
Excel and are typically spread to other
similar documents.
Memory Resident Viruses:
Memory Resident Viruses reside in a
computers volatile memory (RAM). They
are initiated from a virus which runs on the
computer and they stay in memory after
it's initiating program closes.

10. Spy ware
 Spyware, on the other hand, is generally not
designed to damage your computer. Spyware
is broadly defined as any program that gets
into your computer without permission and
hides in the background while it makes
unwanted changes to your user experience.
 Most spyware targets only the Windows
operating system. Some of the more
notorious spyware companies include Gator,
Bonzi Buddy, 180 Solutions, DirectRevenue,
Cydoor, CoolWebSearch, Xupiter, XXXDial
and Euniverse.


11. How Did it Get on Your Computer?
 Spyware usually gets onto your machine
because of something you do, like clicking a
button on a pop-up window, installing a
software package or agreeing to add
functionality to your Web browser


12. How Did it Get on Your Computer?
 Drive-by download - This is when a Web site or
pop-up window automatically tries to download
and install spyware on your machine
 Browser add-ons - These are pieces of software
that add enhancements to your Web browser,
like a toolbar, animated pal or additional search
box.
 browser hijackers -- these embed themselves
deeply in your machine and take quite a bit of
work to get rid of.

13. Steps to avoid virus
 Don’t open e-mail that you are not sure.
 All thumb drive(Pendrive) need to scan by
anti-virus software.

 Always scan your PC with anti-virus software.

14. How to protect your computer from
computer viruses
 Only open e-mail attachments received
from sources you trust and that you are
expecting.

 Back up your hard drive files frequently and
maintain multiple backup sets.

 If you are experiencing unusually slow
performance, apparent file loss or
damage, or other abnormalities,
immediately check your hard drives and
diskettes for infection.

15. •Delete chain emails and junk email. Do not
forward or reply to any to them.
These types of email are considered spam, which is
unsolicited, intrusive mail that clogs up the
network.
•
•Download software only from sites you are
familiar with, and immediately check it with your
anti-virus software.
•
•Don't spread hoaxes and rumors.

16. TOP 10 ANTIVIRUS OF 2017
1. McAfee AntiVirus Plus
2. Symantec Norton AntiVirus Basic
3. Webroot SecureAnywhere AntiVirus
4. Bitdefender Antivirus Plus
5. Kaspersky Anti-Virus
6. Avast Pro Antivirus 2017
7. Emsisoft Anti-Malware 2017
8. ESET NOD32 Antivirus
9. F-Secure Anti-Virus (2017)
10.Trend Micro Antivirus+ Security

18. End

19. References
 http://www.webopedia.com/DidYouKnow/Internet/2004/vi
- The Difference Between a Virus, Worm, and
Trojan Horse.
 http://en.wikipedia.org/wiki/Computer_virus -
Computer Virus
 http://www.microsoft.com/protect/computer/basics/virus.m
- What is Computer Viruses
 http://www.soe.umich.edu/computingnetwork/howto/avo
- How To Avoid Computer Viruses