Information about viruses and their types in the world of technology

1. Computer Virus
BY:
Sarhad Baez

2. Out line
• WHAT IS A COMPUTER VIRUS
• TYPES OF COMPUTER VIRUS
• HOW TO KNOW YOUR PC HAS A VIRUS
• HOW DOES A COMPUTER GET INFECT WITH
A VIRUS
• WHAT IS ANTI-VIRUS
• BEST ANTI-VIRUS SOFTWARE
• SUMMARY
• REFRENCE

3. What is a computer virus
• It is a computer program that can copy itself and infect a
computer without permission or knowledge of the user.
• It is a piece of code that is secretly introduced into a
system in order to corrupt it or destroy data.
• A program which can be transmitted between computers
via networks (especially the internet ) or removable
storage such as CDs, USB drives, floppy disk etc.

4. TYPES OF COMPUTER VIRUS
• Boot viruses
• Program viruses
• Multipartite viruses
• Stealth viruses
• Polymorphic viruses
• Macro Viruses

5. Boot viruses
These viruses infect floppy disk boot records in hard
disks. They replace the boot record program (which is
responsible for loading the operating system in
memory) copying it elsewhere on the disk or
overwriting it. Boot viruses load into memory if the
computer tries to read the disk while it is booting.
Examples: Form, Disk Killer, Michelangelo, and Stone
virus

6. Program viruses
These infect executable program files, such as those
with extensions like .BIN, .COM, .EXE, .OVL, .DRV
(driver) and .SYS (device driver). These programs are
loaded in memory during execution, taking the virus
with them. The virus becomes active in memory,
making copies of itself and infecting files on disk.
Examples: Sunday, Cascade.

7. Multipartite viruses
A hybrid of Boot and Program viruses. They infect
program files and when the infected program is
executed, these viruses infect the boot record. When
you boot the computer next time the virus from the
boot record loads in memory and then starts infecting
other program files on disk.
Examples: Invader, Flip, and Tequila

8. Stealth viruses
These viruses use certain techniques to avoid detection.
They may either redirect the disk head to read another
sector instead of the one in which they reside or they may
alter the reading of the infected file’s size shown in the
directory listing. For instance, the Whale virus adds 9216
bytes to an infected file; then the virus subtracts the same
number of bytes (9216) from the size given in the directory.
Examples: Frodo, Joshi, Whale

9. Polymorphic viruses
A virus that can encrypt its code in different ways so
that it appears differently in each infection. These
viruses are more difficult to detect.
Examples: Involuntary, Stimulate, Cascade, Phoenix,
Evil, Proud, Virus 101

10. Macro Viruses
A macro virus is a new type of computer virus that infects the
macros within a document or template. When you open a word
processing or spreadsheet document, the macro virus is activated
and it infects the Normal template (Normal.dot)-a general
purpose file that stores default document formatting settings.
Every document you open refers to the Normal template, and
hence gets infected with the macro virus. Since this virus attaches
itself to documents, the infection can spread if such documents
are opened on other computers.
Examples: DMV, Nuclear, Word Concept.

11. How does a computer get infected with
a virus
• Downloading any infected software
• Opening e-mail attachments
• Connecting an infected disk, disc, or drive
• Online Ads
• Visiting unknown links

12. Downloading any infected software
When downloading any software via the Internet, make
sure you're downloading the software from a reliable
source. Be sure to run your downloads through your
antivirus and spyware scanners upon completion.
As we stated in a previous section, during the
installation process, read all prompts about what the
program is installing on your computer.

13. Opening e-mail attachments
As a general rule, do not open e-mail you were not
expecting to receive. Computers can become infected when
users open e-mail attachments that contain malicious code.
Even if the message is from a co-worker, friend, or family
member, always use caution before opening a link or
downloading an attachment.

14. Connecting an infected disk or drive
Any disk, or thumb drive connected or inserted into your
computer can be infected with a virus. As long as something
is writable, a virus can move from a computer to that disk,
disc, or drive. A common tactic used by hackers to gain
access to a network is by leaving out a thumb drive with
malicious code on it. Then, when a user puts the thumb
drive into their computer, it becomes infected with a virus.

15. Online Ads
Malicious online ads, also known as Advertising, is just
another way your computer can get a virus without any
realization or traceable evidence. Criminals often place
clean ads on trusted websites and leave them in place
for a while to gain credibility. After some time passes
they put a malicious code in the ad that infects your
computer when clicked on.

16. Visiting unknown links
It is possible for anyone to create a website and if a
malicious person has designed the website it could give
them access to your computer, send malicious files, or
obtain sensitive information about your computer.
Always be cautious and suspicious of any link sent to
you over chat, e-mail, or SMS.

17. How to know your pc has a virus
• Unexpected pop-up windows
• Slow start up and slow performance
• Suspicious hard drive activity
• Lack of storage space
• Missing files

18. How to know your pc has a virus
• Crashes and error messages
• High network activity
• Email is hijacked
• Browser woes
• Security attacks

19. What is anti-virus
Anti-virus software is a program or set of programs that
are designed to prevent, search for, detect, and remove
software viruses, and other malicious software.

20. Best anti-virus software
• BitDefender Antivirus Plus
• ESET NOD32 Antivirus
• F-Secure Antivirus SAFE
• Kaspersky Anti-Virus
• Norton AntiVirus Basic
• Panda Antivirus Pro
• Trend Micro Antivirus+ Security
• Webroot SecureAnywhere AntiVirus

21. Reference
• https://www.webroot.com/in/en/home/resources/t
ips/pc-security/security-what-is-anti-virus-
software
• Kizza, Joseph M. (2009). Guide to Comaputer
Network Security. Springer.