COMPUTER

VIRUS AND

Its Types…

A computer virus

is a type of malicious software program , when executed, replicates by reproducing itself or infecting other computer programs by modifying them.

Who created the first virus and when ?

The first virus was created by

the two pakistani brothers Amjad Farooq Alvi and Basit Farooq Alvi  in 1986 and was named as “Brain”

HOW DOES A VIRUS WORK?

Some viruses attack the

computer’s boot sector, the area on the hard drive that hosts the code for the start-up routine. Such a root code virus causes havoc because it runs itself every time you switch on the computer. Other viruses are hidden in emails, games or attached documents.

THREE TYPES OF COMPUTER INFECTIONS ARE:

1.VIRUSES2.WORMS3.TROJAN HORSES

Till now more than seventeen million

computer viruses are there in the world !!!!

1. RESIDENT VIRUSES: THIS TYP E OF V IRU S IS A PERMANENT WHICH DWELLS IN THE R AM MEMORY. FR OM THERE I T CAN OVERCOME AND INTER RU PT ALL OF THE OP ERAT IONS EXECU TED BY THE SY STEM . EX : RANDEX

2 . MU LT IPART ITE V IRU SES : MULT IPART ITE  V IR U SES  ARE D ISTR IBUTED THR OU GH INFECTED MEDIA AND U SUALLY H IDE IN THE MEMORY. GRADUALLY, THE V IRU S MOVES TO THE BOOT SECTOR OF THE HAR D DR IVE AND INFECTS EXECU TABLE F I LES ON THE HARD DR IVE AND LATER ACROSS THE COMP UTER SYSTEM. .

3 . D IRECT ACT ION V IR USES : T H E M A I N P U R P O S E O F T H I S V I R U S I S T O R E P L I C AT E A N D TA K E A C T I O N W H E N I T I S E X E C U T E D . W H E N A S P E C I F I C C O N D I T I O N I S M E T, T H E V I R U S W I L L G O I N T O A C T I O N A N D I N F E C T F I L E S I N T H E D I R E C T O R Y O R F O L D E R T H AT I T I S I N A N D I N D I R E C T O R I E S T H AT A R E S P E C I F I E D I N T H E A U T O E X E C . B AT F I L E PAT H .

Viruses

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4. Boot Virus : This type of virus affects the boot sector of a floppy or hard disk. This is a crucial part of a disk, in which information on the disk itself is stored together with a program that makes it possible to boot the computer from the disk.

5. Encrypted Viruses : This type of viruses consists of encrypted malicious code, decrypted module. The viruses use encrypted code technique which make antivirus software hardly to detect them.

6. Stealth Viruses : Stealth Viruses is some sort of viruses which try to trick anti-virus software by intercepting its requests to the operating system. It has ability to hide itself from some antivirus software programs. Therefore, some antivirus program cannot detect them.

Trojans or Trojan Horses :Another unsavory breed of malicious code (not a virus as well) are Trojans or Trojan horses, which unlike viruses do not reproduce by infecting other files, nor do they self-replicate like worms.

Worms : A worm is technically not a virus, but a program very similar to a virus; it has the ability to self-replicate, and can lead to negative effects on your system and most importantly they are detected and eliminated by antiviruses. EX : Code Red

Activation of VirusWhen the computer virus starts working, it is called the activation of virus. A virus normally runs all the time in the computer. Different viruses are activated in different ways. Many viruses are activated on a certain data. For example, a popular virus“Friday, the 13th” is activated only if the date is 13 and the day is Friday.

Causes of

Computer Virus :

Infected Flash Drives or Disks

Email Attachments Infected websites Networks Pirated Software

Damages caused by virusComputer virus cannot damage computer hardware. IT may cause many damages to a computer system.

A computer virus can damage data or software on the computer.

It can delete some or all files on the computer system.

It can destroy all the data by formatting hard drive.

It may display a political or false message very few times.

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