Computer Viruses


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Information about computer viruses..


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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. . 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:

Types of COMPUTER viruses Stealth viruses Use certain techniques to avoid detection. Macro Viruses I nfects 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.

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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:

Virus through the Internet Today almost 87% of all viruses are spread through the internet (source: ZDNet)

Trojan Horse:

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


SYMPTOMS Computer runs slowly Random restarts U nknown 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?:

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?:

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:

Top Seven Antiviral Programs Kaspersky Antivirus Avira Antivirus Mcafee Antivirus Symantec Norton Antivirus Bit Defender 2010 Quick Heal Antivirus AVG Antivirus

General Security Tips:

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

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Made By- Vivek Sharma 10 th A END !

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