Class 10 Computer Science Note


computer virus

A computer virus is a type of computer program that can replicate itself by making copies of itself by making copies of itself without the user's knowledge or consent.


Computer virus spread from following ways

i. Opening the infected email attachment.

ii. By downloading infected programs from the internet.

iii. By using infected floppy disk, pen drives and CDs.

iv. By transferring an infected program over a network and executing it.


Type of computer virus

i) Boot Sector Virus

Boot Sector virus is regarded as one of the most hostile types of virus, a boot sector virus infects the boot record of a hard or a floppy disk. The virus moves the boot sector data to a different part of a disk. This virus allows the actual boot sector data to be read as though a normal start up were occurring.

ii) File Infecting Virus

This type of virus infects program files on a disk. When infected program is launched, the virus code is also launched. After the virus code has been launched, it will normal load and execute the program that has been infected.

iii) Multipartite Virus

This virus is the combination of parasitic and boot sector virus and due to this, it is able to infect both the files or boot sector of a disk. They infect program files and when it is executed, these viruses affect the boot record.

iv) Macro Virus

These viruses infect the Microsoft Office programs such as Excel, Word, Access and PowerPoint. When we open the Microsoft program then the virus is loaded and it affects the normal template or document. Since it is attached in the document, if the infected document is opened on other computer, it affects the computer too.

v) Script Virus

Script Virus is written in script programming languages, such as VBScript and JavaScript. It can infect a computer through various scripting environments, such as Windows Help, Windows installation files and Windows registry files.


The symptoms of computer viruses

i. Programs take long time to load.

ii. Renaming all the files with different names.

iii. Shows unusual error messages on the screen frequently.

iv. Corrupt or deletes system data and programs.\


Anti-virus software

Anti-virus software is a computer program designed to detect and remove viruses from the computer system. 


Avoid the virus attacks

i. Scanning the email attachment before executing them.

ii. Use of a good anti-virus program to scan for viruses.

iii. Scanning the disk frequently for viruses.

iv. Not installing the pirated software, especially computer games.

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