Page 83 - TP_Prime_V2.2_Class7
P. 83

Harms Caused by Computer Viruses
 07              Different viruses will affect your computer in different ways:


                 •   They can crash your hard disk.

                 •   They can destroy all or some of your data.

                 •   They decrease the processing speed of the computer.
 Prime (Ver. 2.2)-VII  •   They can reduce or block the memory of the computer or hard disk.                                COMPUTER VIRUS


                 •   They stop you from restarting your computer or keep on restarting your computer.

                 •   They can send e-mails from your account without your knowledge.


                   Types of Computer Virus



                 There are various types of computer viruses that infect the computer in different ways. The
 80                                                                                                                       81
                 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  virus, also known as file-infecting virus is a type of computer virus that
                 infects executable files (program files such as .exe, .com, .sys, etc.,) to make them unusable

                 or damage permanently. When an infected program file is executed, the code of the virus is
                 also executed.

                 Once a virus has been executed, it remains active in the memory of the computer and can
                 infect  other  programs.  Sometimes,  a  program  file  virus  is  called  file  injector.  The  most

                 commonly known program file viruses are Jerusalem and Cascade.


                     Boot Sector Virus

                 A Boot  sector  virus  is one of the most hostile types of computer viruses which infects

                 the  boot  sector  or  the  Master Boot Record  (MBR)  of  hard  disks  or  floppy  disks.
                 Once a computer system is infected by a boot sector virus, any disk connected to the computer

                 will also be infected. The most commonly known boot sector viruses are Michelangelo and

                 Stoned.
   78   79   80   81   82   83   84   85   86   87   88