A BRIEF HISTORY AND KNOWLEDGE (INTRODUCTION) ABOUT COMPUTER VIRUSES

A BRIEF HISTORY AND KNOWLEDGE (INTRODUCTION) ABOUT COMPUTER VIRUSES

A computer virus is computer code that is designed to insert itself into other  

software and, when executed, is able to replicate itself and propagate with the  

host software or file. Viruses can be designed to damage the infected host by  

corrupting files, stealing hard disk space or CPU time, logging keystrokes  

to steal passwords, creating embarrassing messages, and other activities all  

performed without the computer user’s approval or knowledge. Early viruses  

were boot sector viruses and spread by computer users sharing infected  

floppy disks. Other viruses attached to e-mail or a part of the body of an  

e-mail, and when the code viruses were executed, a message with the virus  

embedded was sent to other mail clients. In some cases, the code could be  

designed to provide the scripts access to the user’s address book and could,  

in turn, propagate and use those addresses to further propagate the virus- 

infected message. Other viruses were designed to be attached to data files  

such as word documents or spreadsheets. These scripts are visual basic code  

that can execute when the file is loaded, and once the virus has attached itself  

to an application, the code in the virus will run every time the application  

runs