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COMPUTER VIRUSES

WHAT IS A COMPUTER VIRUS?

A computer virus is a small software program that spreads from

one computer to another computer and that interferes with

computer operation. A computer virus may corrupt or delete data

on a computer, use an e-mail program to spread the virus to other

computers, or even delete everything on the hard disk. 

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CHARACTERISTICS OF A COMPUTER VIRUS:

the ability to replicate itself.

the ability to attach itself to another computer file.

WORKING OF COMPUTER VIRUS

A Computer Virus needs another program in

order to be able to be activated and infect other

computers files.

For example, a virus might attach itself to a

spreadsheet program. Each time the program runs,

the virus runs too.

A file containing virus is called infested file.

TYPES OF COMPUTER VIRUSES

Stealth viruses

Use certain techniques to avoid detection.

Macro Viruses

Infects the macros within a document or template.

Polymorphic viruses

Encrypt its code in different ways

Metamorphic viruses 

Rewrite themselves each time

they infect a new file.

Boot viruses

Affects boot sector of a floppy or hard disk.

Program viruses

Infect executable program files.

Multipartite viruses

A hybrid of Boot and Program viruses.

Directory Virus

Directory viruses change the paths

that indicate the location of a file

TYPES OF COMPUTER VIRUSES

VIRUS THROUGH THE INTERNET

Today almost 87% of all viruses are spread through

the internet (source: ZDNet)

87%

13%

Inter...

TROJAN HORSE

Covert

Leaks information

Usually does not

reproduce

WORMS

Spread over network connection

Worms replicate

First worm released on the Internet was called

Morris worm, it was released on Nov 2, 1988.

WHAT CAN VIRUSES DO?

Format hard disk

Copy, rename and delete files

Modify files dates and extensions

Display false message every few times

Damage data

Damage software

SYMPTOMSComputer runs slowly

Random restarts

Unknown and uninstalled icons on desktop

Icons change in appearance

System memory and disk space is reduced

New windows open up at an alarming rate

Error messages on regular basis

Files mysteriously disappear

HOW VIRUS SPREADS?

Email

Opening and downloading an email containing virus

Networks

Connecting with network that contains virus

Removable Storage Media

Floppy discs, CDs and flash devices

Pirated Software

Installing pirated software that contains virus

WHO CREATES VIRUSES AND WHY?

Common people:

For fun

Release anger

Take revenge

For fame

Profit earners:

Antivirus market

Info attackers:

Disrupt enemy’s information and network

HOW TO PROTECT FROM VIRUS?

Latest antivirus should be installed

Antivirus software must be upgraded regularly

Unknown emails should not be opened

Unauthorized software should not be installed

Removable storage media should be scanned

Freeware and shareware software from internet

should be checked before installing

TOP SEVEN ANTIVIRAL PROGRAMS

Kaspersky Antivirus

Avira Antivirus

Mcafee Antivirus

Symantec Norton Antivirus

Bit Defender 2010

Quick Heal Antivirus

AVG Antivirus

GENERAL SECURITY TIPS Apply user-level security on file sharing

when needed.

Don't open email attachments from

unknown senders.

Use Rich Text Format files instead of

Word Documents.

Updated anti-virus program

Set the BIOS boot sequence

Write protection

Made By- Vivek Sharma

10th A

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