This will help you to understand some of the computer security threats available and help you get defended!

2.  When we use computers it is important to prevent corruption and lost of
user
data and let user to continue his work without any disturb. For this we must
secure our data.
 So it is very important to implement good security mechanisms.

4. Unauthorized Action
• Hacking
• Cracking
Malicious software
Virus
Worm
Trojan Horse
Time Bomb
Logic Bomb

5. Unauthorized Access
Hacking
• Trying to access or accessing the network by breaching the security by an
unauthorized person is known as hacking.
• Cheating others account numbers, credit card numbers and misuse them.
• Cheating trade secrets, confusing network devices are done by hacking.
• The person who does this is called a hacker.

6. Cracking
•
Changing software content, Serial number, security methods etc.
•
This done by a programmer who is not licensed to do so is called
cracking

7. Malicious software
• Malware or Malicious software is software designed to damage a computer system
without the owner's concerns.
• Malicious software is a general term used by computer professionals to mean a
variety of annoying software or program codes.
• Malicious software includes Virus, Worm, Trojan, Adware, Root kit, Spyware and
many other unwanted software.

8. Computer Virus
• A computer virus is a program code that can copy itself and infect a
computer without the permission of the user.
• In order to replicate itself, a virus must be permitted to execute and write
to memory.
• For this reason, many viruses attach themselves to an executable files
that
may be part of legitimate programs. Some viruses change its own code by
itself.
• Viruses spread via network, floppy disk, CDs, USB drive.

9. Symptoms of a virus attack
•Changes file size.
•Change system date and time.
•Slow down the computer.
•Shut down computer unexpectedly.
•Take more time to boot computer.

10. Worm
• Worm is a self-replicating computer program.
• It uses a network to send copies of itself to other systems and it may do so withou
any user intervention.
• Unlike a virus, it does not need to attach itself to an existing program.

11. Trojan horse
• This is a program that disguises itself as program.
• Similar to a virus, these programs are hidden and cause an unwanted effect.
• They differ from viruses because they are normally not designed to replicate like
a virus.
•By showing that this is important software running in the computer the Trojan
horse opens a back door to the hacker.
• There after unauthorized person can get into the computer and do harmful to
the user data.
E.g.: By opening unknown e-mail attachments

12. Symptoms when Trojan horse affects the computer:
•Sending the user’s important details to others.
•Changing or deleting data of the computer.
•Uploading and downloading data in an unauthorized way.
•Spreading malware such as viruses.
•Shutting down the computer unexpectedly.
•Unauthorized Software installation.

13. Boot sector virus
• This is a virus which infects the boot sector of a hard disk or other disk drives.
• The boot sector is the portion that stores the boot program that has the code fo
loading the operating system file onto memory.
• Once the boot sector is infected with the virus, it may rewrite the boot sector
making it unbootable or scramble the File Allocation Table (FAT).

14. Symptoms when Boot Sector Virus affect the computer:
•Sudden error massages.
•Windows restart with a blue screen error message.
•Boot Failure.
•Fail to format a particular drive.

15. Stealth Virus
• These viruses may be one of the type mentioned, but are designed to defeat
antivirus scanning and other antiviral software detection method (firewall).
• Mode of infection is from fake antivirus and software promoting website.
• This virus helps the other viruses too.

16. Spyware
• Software that is installed into a computer without the user's knowledge.
• Transmits information about the user's computer, and user activities over the
Internet.
• Redirect to sites which spoil the culture and the computer.

17. Symptoms when Spy ware affects to your computer:
• Sending user’s important data to others.
• Unauthorized Software installation.
• Redirect Web browser to dangerous web sites.
• Change Computer settings.
• Using anti-spyware we can minimize the damages.

18. Time Bomb
• This is simply some code on a computer which does not immediately trigger.
• Instead, it is set to cause it's damage at some point in the future.
• Usually Time bombs are designed to take revenge towards a company or an
organization.
‍ E.g.: Sending messages such as “You are a great FOOL!!!!” on April first.
OR
“Am the vampire who suck ur blood” at 12 P.M

19. Logic bomb
• A logic bomb is a program which will execute a pre-programmed routine when a
designated condition is met.
• Logic bombs do not make copies of themselves.
• Logic bomb work as same as time bomb.

21.  The large scale of creating virus is for business.
 Taking revenge.
 Like to see others suffering.
Mentally Affected
 Hobby and fun.
For virus creators?
How would you feel if your important files are corrupted or deleted? Its
pretty bad, it cause redoing all of our work. Therefore, creating and
spreading viruses is an activity one must never indulge in. After all,
everyone’s work is as precious as our are.