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•  They can destroy all or some of your data.

                  •  They decrease the processing speed of the computer.
                  •  They can reduce or block the memory of the computer or hard disk.

                  •  They stop you from restarting your computer or keep on restarting your computer.
                  •  They send e-mails from your account without your knowledge.


                   i +   TYPES OF COMPUTER VIRUS

                  There are various types of computer viruses that infect the computer in different ways. The most
                  commonly known categories of computer viruses are:
                  •  Program File Virus

                  •  Boot Sector Virus
                  •  Macro Virus

                  •  E-mail Virus
                  Let us learn about these in detail.

                  Program File Virus

                  A program file infecting virus is a type of malware that infects the executable files of a program
                  with the intention of causing permanent damage or making the program useless. A file-infecting
                  virus overwrites the code or inserts infected code into the source of an executable or program
                  file. When such programs are executed, such virus is activated and damages the files. When
                  a  program  is run  repeatedly,  program  viruses are  deliberately  loaded  in a  program  by  the
                  developer. A program file infecting virus is also known as a ‘File Injector’. Sunday and Cascade
                  are the common examples of program viruses.

                  Boot Sector Virus

                  Booting is the process of loading operating system in the primary memory from the boot sector. Boot
                  sector is the core area of hard disk storage where the most important program like OS are stored.
                  A boot sector virus gains complete control over the Master Boot Record (MBR). MBR is the
                  first sector of the computer hard drive that stores the information about loading the operating
                  system into the main memory.

                  Boot Sector virus replaces the location and information of the operating system in order to stop
                  it from getting loaded into main memory resulting into errors during booting. Michelangelo,
                  Polyboot.B, Stones and AntiEXE are some common examples of boot sector virus.

                  Macro Virus

                  A macro virus is a type of computer virus that is primarily designed to infect a specific type of
                  document, such as Word or Excel files. If we open a macro virus infected document, the macro
                  virus gets active in the memory and starts infecting other documents. Sometimes, a macro virus
                  sends itself as an e-mail attachment to the people in the user's address book. Melissa and Bablas
                  are the most commonly known macro viruses.



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