Today I’m going to talk about: Computer virus I’ve divided my presentation into two parts: First I’d like to introduce of this virus and second I’ll presenttypes of virus. So, let’s start with introduce Virus (computer), self-duplicating computer program that interfereswith a computer’s hardware or operating system. Viruses are designed toduplicate or replicate themselves and to avoid detection. Like any othercomputer program, a virus must be executed for it to function, it must belocated in the computer’s memory, and the computer must then follow thevirus’s instructions. These instructions are called the payload of thevirus. The payload may disrupt or change data files, display an irrelevantor unwanted message, or cause the operating system to malfunction.Computerviruses activate when the run programs are opened. Once a virus is active,it may replicate by various means and tries to infect the computer’s filesor the operating system. For example, it may copy parts of itself to floppydisks, to the computer’s hard drive, into legitimate computer programs, orit may attach itself to e-mail messages and spread across computer networksby infecting other shared drives.
Finally let’s consider: with types of viruses There are five categories of viruses: parasitic or file viruses,bootstrap sector, multi-partite, macro, and script viruses. Parasitic or file viruses infect executable files or programs in thecomputer. These files are often identified by the extension . File virusesleave the contents of the host program unchanged but attach to the host insuch a way that the virus code is run first. These viruses can be eitherdirect-action or resident. A direct-action virus selects one or moreprograms to infect each time it is executed. A resident virus hides in the
computer’s memory and infects a particular program when that program isexecuted. Bootstrap-sector viruses reside on the first portion of the hard diskor floppy disk, known as the boot sector. These viruses replace either theprograms that store information about the disk’s contents or the programsthat start the computer. Typically, these viruses spread by means of thephysical exchange of floppy disks. Multi-partite viruses combine the abilities of the parasitic and thebootstrap-sector viruses, and so are able to infect either files or bootsectors. These types of viruses can spread if a computer user boots from aninfected diskette or accesses infected files. Other viruses infect programs that contain powerful macro languages.These viruses, called macro viruses, are written in macro languages andautomatically execute when the legitimate program is opened. Script viruses are written in script programming languages, such asVBScript (Visual Basic Script) and JavaScript. These script languages canbe seen as a special kind of macro language and are even more powerfulbecause most are closely related to the operating system environment. The“ILOVEYOU” virus, which appeared in 2000 and infected an estimated 1 in 5personal computers, is a famous example of a script virus.