This document provides an overview of computer viruses including their history, types, symptoms, and prevention methods. It discusses how the first computer virus was created in 1981 and that now there are millions of viruses. There are eight main types of viruses that can damage systems like boot sector viruses or hijack browsers. Common symptoms of a virus include slow performance, freezing, and unauthorized program activity. The best prevention methods are installing antivirus software, keeping systems updated, avoiding suspicious attachments/websites, and not using pirated software.

1. Computer Virus
Prepare by- Shripati pritam sahoo
Date:-may,2023

2. Table of Content
 History
 What is computer virus
 Symptoms
 Types of computer virus
 The spread of the virus
 What computer virus do
 Preventation from computer virus
 Best antivirus software
 Conclusion

3. History of computer virus
 The first computer virus was called creeper.It was
invented in the early 1970’s. Since then, millions
of viruses have been invented.
 The first known computer virus was written in
1981 by a man named Rich Skrenta. This virus
was termed Elk Cloner, and was the first computer
virus to appear outside the computer where it was
created in.

4. What is computer virus
 A computer virus is a malicious application used to
perform destructive activity on a device or local
network.
 The code’s malicious activity could damage the local
file system, steal data, interrupt services, download
additional malware, or any other actions coded into
the program by the malware author.

5. Symptoms
 Your computer or web browser has dramatically slowed down over a period of
a few days/a week
 Frequent freezing or crashing
 Modified or deleted files
 New programs or desktop icons that you do not recall installing/creating
 Programs running without your consent
 Programs closing without your consent
 Changes in your security settings
 Unusual emails/social media messages being sent without your permission to a
large audience
 Your default search engine has been changed without you altering it
 New toolbars in the web browser
 Browser links redirect to the wrong web page

6. Types of Computer virus
There are eight main virus types, some of which could be packaged with
other malware to increase the chance of infection and damage. The 8
major categories for viruses are:
1.Boot Sector virus- A boot sector virus damages or controls the boot sector on
the drive, rendering the machine unusable.
2.Direct action virus-When a user executes a harmless file attached with
malicious code, direct action viruses deliver a payload immediately.
3.Web scripting virus-Most browsers have defenses against malicious web
scripts, but older, unsupported browsers that allow an attacker to run code
on the local device.
4.Polymorphic virus-Polymorphic viruses make it more difficult for an antivirus
to detect and remove them
5.File infector virus-A threat actor uses file infector viruses to inject malicious
code into critical files that run the operating system or important programs

7. 6.Browser hijacker- A virus that can change the settings on your browser
will hijack browser favorites, the home page URL and redirect you to a
malicious site
7.Resident virus- A virus that can access computer memory and sit until
a payload is delivered is considered a resident virus.
8.Macro virus- Microsoft Office files can run macros, and these macros
can be used to download additional malware or run malicious code. Macro
viruses deliver a payload when the file is opened, and the macro runs.

8. Latest viruses
 DEXTER-
 Dexter is a computer virus or point of sale
malware which infects computers running Microsoft
Windows and was discovered by IT security, in
December 2012.
 It infects PoS(point of sale) systems worldwide and
steals sensitive information such as Credit Card and
Debit Card information.

9.  REVETON-
1.In 2012, a major ransomware know as Reveton
began to spread.
2 .Reveton is a malware which attempts to extort
money from a user.
3 .It Claims that your computer has been used for
unauthorized activites.

10.  CRYPTOLOCKER-
1.encrypting ransomware appeard in 2013 known
as Crypto Locker.
2.cryptolocker demands a pyment with either a
moneyPak card or Bitcoin to recover the key.
3.cryptolocker to be extremely difficult to repair.

11. The spread of the virus
1.Infected applications move from one computer to
another easily because users are unaware their
application is infected and will share, transfer, or install
them without a care in the world.
2.Some users are unaware that their email software is
being controlled by the virus (mail hijack) and viruses
are actually emailing themselves to the contacts in the
email contacts list.
3.Users can also download viruses if they are using
pirated apps, or have accessed an infected code
repository.

12. What does a computer virus do?
The way a computer virus acts depends on how it’s coded. It could
be something as simple as a prank that doesn’t cause any damage,
or it could be leading to criminal activity and fraud. Many viruses
only affect a local device, but others spread across a network
environment to find other hosts.

13. How to prevent computer viruses
 Install antivirus software: Antivirus should run on
any device connected to the network. It’s your first
defense against viruses. Antivirus software stops
malware executables from running on your local
device.
 Don’t open executable email attachments: Many
malware attacks including ransomware start with a
malicious email attachment. Executable attachments
should never be opened, and users should avoid
running macros programmed into files such as
Microsoft Word or Excel.

14.  Keep your operating system updated: Developers for all
major operating systems release patches to remediate common
bugs . Always keep your operating system updated and stop
using end-of-life versions (e.g., Windows 7 or Windows XP).
 Avoid questionable websites: You should always keep your
browser updated with the latest patches, but avoiding these
sites will stop drive-by downloads or redirecting you to sites that
host malware.
 Don’t use pirated software: Free pirated software might be
tempting, but it’s often packaged with malware. Download
vendor software only from the official source and avoid using
software that’s pirated and shared.

15. Best antivirus software
1.McAfee
2.Nortan
3.TOTALAV
4.Intego
5.Bitdefender
6.Panda
7.PROTECT

16. Conclusion
In our technology- dependent society, the computer
is the mastert it controls our entertainment, our
power plants, our military and much more.
However, because of the dependency on the
computer and other technologies, the virus can easily
do millions or even billions of dollars in damage.

17. THANK YOU