What is computer virus and type of computer virus?

**Geaty** · **Geaty** Sun 15 May 2016, 9:18 pm

What is computer virus and type of computer virus? I have heard of enough of this computer virus, i really wnt to know much about it.

**Paradise** · **Paradise** Sun 15 May 2016, 9:40 pm

A computer virus is a program, a block of executable code,which attaches itself to the computer in order to overwrite or replace anothe program. It produces itself easily without the knowledge of the computer user.

One can say that a computer virus is a small softawre program that interferes with computer operation and spreads from on computer to another. Computer virus may corrupt or delete data(information) on a computer or even delete everything on the hard disk.

Computer viruses are most spread bu attachmentd via email or by instant messaging. They can be disguised as attachments of funny images, greeting cards or audio and vidio files. They also spread by using download facility on the Internet and can be hidden in pirated softare or in other files or program that you may download.

TYPES OF COMPUTER VIRUS
There are many computer viruses such as boot sector viruses, parasitic viruses, multiparasitic viruses, link viruses, macro viruses and companion viruses etc.

1. Boot Sector Virus: This was created by Farooq Alvi Brothers (Basit and Amjad), in Pakistan in 1986. The virus was called (c)Brain. The virus was created to fight th piracy of the software they had developed.

Boot sector virus attacks a system that is started or booted with the infected floopy disk.

2. Executable File Virus: These are viruses that are found in the attached to executable files. In order to replicate itself, it must be permitted to execute its code and write to memory. This is why many viruses attach themselves to executable files that may be part of legitimate program. So, whenever a user tries to start an infected executable file, the virus code will be executed first.

Example of Viruses
There are variuos types of virus known and nez viruses are being written on a daily basis. An example is the CiaDoor virus, which diables system restore and other tools like. Task Manager and Command Prompt. Below are some of the known viruses:

1. Trojan Horse virus
2. Sleeper virus
3. Logic bomb virus
4. Alabama virus
5. Christmas virus
6. Jerusalem virus
7. Creaper virus
8. Macro virus
9. Cross-site scripting virus
10.Nonresident viruses
11.Resident viruses
12.CiaDoor virus
13.W32/Bugbear@MM
14.W32/BadTrans@MM
15.Code Red
16.Downloader-W
17.November 17
18.JS/No Close
19.Melissa
20.I Love You
21.W32/Elkern.cav
22.Stone
23.Data
24.Antiexe.