virus

Prepared by:-Rauhl kundu6th sem,IT

Content

Definition of virus

Types of virus

Definition of virus

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge & runs against your wishes.

Viruses can also replicate themselves.

All computer viruses are man-made.

Type of viruses

1. File infector virus2. Boot sector virus3. Master boot record virus4. Multi-partite virus5. Macro virus6. Script virus7. Companion virus

1) File infector virus

It infects files with .exe or .com extensions.

When the infected file is accessed or executed, it may be partially or completely overwritten by the virus.

1) File infector virus

A file infecting virus may be known as a file infector.

After memory is infected, any non-infected executed that runs becomes infected.

E.g.:- Jerusalem & cascade.

2) Boot sector virus

It is a computer virus that infects a storage devices floppy/MBR.

A boot sector virus is able to infect a computer only if the virus is used to boot up the computer.

E.g.-disk killer, stoned, michelangelo

3) Master Boot record virus

Similar to boot sector virus.

An MBR virus is common type of virus that replaces the MBR with it own code.

A small program that is executed when a computer boots up.

E.g.-NYB, AntiExe, unashaned

4) Multi-partite virus

Infect boot records and programs files.

Difficult to repair.

Boot area & files must both be cleaned of virus or re-infection will occur.

E.g.-one half, emperor, anthrax, tequila

5) Macro virus

Most common type of virus.

Infect data files like word, excel, power presentation, access files.

E.g.-W97m.melissa, WM.NiceDay & W97M.groov

6) Script virus

Infect various script language such as dos, java script & visual basic script.

7) companion virus

A virus which infects executable files by creating a ‘companion’ file with the same name but an .com extension.

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