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MO/DUTUGEMUNU CENTRAL COLLEGE

Edited :- Kanchana Eranga Bandara

Computer Security Threats

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.

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FROM WHAT/WHOM WE HAVE TO SECURE DATAS AND COMPUTERS….?

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Unauthorized Action• Hacking • Cracking

Malicious software Virus Worm Trojan Horse Time Bomb Logic Bomb

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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.Edited :- Kanchana Eranga Bandara

Cracking

• Changing software content, Serial number, security methods etc.

• This done by a programmer who is not licensed to do so is called cracking

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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.

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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. Edited :- Kanchana Eranga Bandara

• Changes file size. • Change system date and time.

• Slow down the computer.

• Shut down computer unexpectedly.

• Take more time to boot computer.

Symptoms of a virus attack

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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 without any user intervention.

• Unlike a virus, it does not need to attach itself to an existing program.

Edited :- Kanchana Eranga Bandara

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

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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.

Edited :- Kanchana Eranga Bandara

• 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 for 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).

Boot sector virus

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• Sudden error massages.

• Windows restart with a blue screen error message.

• Boot Failure.

• Fail to format a particular drive.

Symptoms when Boot Sector Virus affect the computer:

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• 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.

Stealth Virus

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• 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.

Spyware

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• 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.

Symptoms when Spy ware affects to your computer:

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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 “vampire time” at 12 A.M

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• 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.

Logic bomb

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Why & Who Create Viruses…?

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The large scale of creating virus is for business.

Taking revenge.

Like to see others suffering.

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.

Mentally Affected

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Deleting Viruses & Recovering Computer (Without using an antivirus)

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Step 1:

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Step 1:

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Step 2:

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Step 2:

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Thank You!

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