. MOST IMPORTANT VIRUSES.

1.Boot sector virus.

                                  2.Chernobal virus.

3.Logic bomb.

                                  4.Torjan horse.

5.Redlof.

 

1.BOOT SECTOR VIRUS.

               A disk is divided into tracks and sectors.The disk that contains operating system has a special program in its first sector.The sector is know as boot sector.The program in boot sector is automatically loaded in memory when computer starts.The program then loads operating system in te memory.

             The boot sector virus modifies the program in the boot sector.It is loaded into memory whenever computer is turned on.The virus is attached with the executable files like .exe, .com and .dll files.When the user uses these files,the virus attached with these files is activated .It infects other files and performs destructive commands and destroys data files.

 

2.CHERNOBAL VIRUS.

           The famous chernobal virus deletes all microsoft office files.It also deletes te partition information from the disk tat  causes a major loss of data.

 

3.LOGIC BOMB.

           Logic bomb is also calle time bomb.It siffers from oter viruses.It is activated at a certain date and time.Michelangelo is an important logic bomb .It destroys data on the hard disk on march 06.

 

4.TORJAN HORSE.

             Torjan horse hides itself as useful program.It contains hidden instructions to erase data or cause oter damage.It executes illegal, destructions in the middle of a program such as computer game.FormatC is an example of a Torjan horse.

 

5.REDLOF.

         Redlof is a polymorphic virus.It is written in Visual basic script.It relies on the Microsoft ActiveX Component to execute itself.It locates Folders.htt and infects tat file.Folder.htt is  part of Microsoft Windows Active Desktop feature.

         Some viruses make unnoticeable changes.Tey corrupt data being used.Some viruses may make data unusable.

      A virus may detect some special information like passwords or sensitive data.It may send te data to some other user on a network.For example a virus may read the pin code or credit card number and then send it to another user.A virus may also make some resources unavailable to te users.Foe example,a virus may start sending data a network.The network may become unavailable for the user.

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Witer  By Zeeshan.

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