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Computer Virus


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Computer Virus

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Computer Virus

  1. 1. A computer virus is a program or a set of programs that disrupts the normal operation of a computer . Virus infects or destroys data . It enters in the computer without the permission or knowledge of the user . stands for Vital Information Resources Under Seize. The essential resources like memory, processing speed, data & programs etc. cannot have normal operations and can be harmed when virus is spread. Viruses are self-replicating & are continuously expanding their reach by infecting more computer files, resulting in loss of speed & destruction of data. It enters through an infected floppy or Internet / E-mail.
  2. 2. Virus remains undetected & quietly inactive & waits for a particular signal or an event to trigger them. Some virus programs monitor the clock in the host computer & trigger on a certain day, like Friday the 13th. A biological virus causes physical harm to our body and attack certain cells, whereas computer virus causes harm to the data and programs stored in computer by over writing them with garbage or erasing them. Trojan Horses, Worms & Spyware are some other terms which are associated with virus programs but are actually different from virus programs. Trojan Horse : They are non replicating simple but destructive programs which spreads from one system to another when it is copied. Worm : Is a special virus that can replicate itself and use memory but cant add itself to other programs. Malware : Is a trouble causing program which interrupt the normal working of a computer by stealing important information and damages it without the knowledge of the user.
  3. 3. Spyware: It is a type of malware that is installed on computers and collects information about users without their knowledge. They secretly monitor the user’s computing and also collect various types of personal information about internet surfing habits, visited web pages and transmits the same in the background to someone else. Types of viruses : Viruses can be classified into two major categories. 1. Boot Viruses: They infect the boot record or master boot records by replacing the same which is responsible for loading the operating system in memory by copying it elsewhere. Examples are – Disk killer, Stoned virus. 2. Program File Viruses: They infect executable files, programs such as those with extension like .com, .exe, .ovl, .drv, .sys etc. These programs get loaded during execution and becomes active by replicating, also infecting files on the disk. Sunday, Cascade etc. are the examples of Program file virus.
  4. 4. VIRUS SYMPTOMS: The symptoms of virus infection in computer can be detected in many ways such as Decreasing computer speed, causing strange movements or patterns on screen, displaying unusual messages, frequent hanging of the system, Reformatting the hard disk, deleting or damaging files etc. PREVENTING A VIRUS INFECTION : To prevent virus infection every pc should be equipped with some anti-virus program, perform scan for virus infection before running or copying files from external devices, not installing pirated software, perform periodical scanning hard disk, using internet and e-mail attachments very carefully. ANTIVIRUS SOFTWARE : Antivirus software are computer programs which are designed to indentify, prevent and remove viruses from our computer. Antivirus programs scan the computer files to look for known viruses matching definitions from virus dictionary and also identify suspicious behavior from any computer program which indicates infection.