Computer Viruses |
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What is a virus? |
What is a virus?A computer program that is loaded on your computer without your knowledge, with the intent of doing some damage to your system. The effect of computer viruses varies from doing so little damage that you are unaware that your computer has been infected, to wiping out the entire contents of your hard disk. There are viruses which play music, display messages, change or delete files. Computer viruses are manmade and most are intentionally designed to replicate themselves. When the virus program runs it makes a copy of itself and adds itself to another computer program. Each time the infected program is run, the virus is also run and in this way spreads. If your system is infected, you can easily spread the virus to others through shared disks and email attachments. Different types of virusesFile infectors: A block of code which attaches itself to another program and is able to copy itself into subsequent applications that you run. Boot-sector viruses infect the area of the hard disk that are read and executed by the computer when it starts up. Macro viruses: Macros are small programs that can be used to carry out tedious repetitive tasks. For example, you can write a Word macro to add your name, address and phone number to documents. Macros run automatically when the file they are attached to is opened. Macro viruses spread much more rapidly than other forms of viruses as people frequently share data files. The most recent viruses have been spread via email. The Love Bug was a macro virus that caused considerable damage. The subject of the email was 'iloveyou' and had an attached file called 'love-letter-for-you.txt.vbs.' The attachment was a Visual Basic macro that erased files on your computer. The virus then sent copies of itself to every address in the Microsoft Outlook address book. As these replicated messages spread they created jams in Internet traffic and the vast amount of mail caused Network servers to crash. It spread round the world in two hours affecting tens of millions of computers. The term 'trojan horse' is used to describe a virus program that disguises itself as a benign application. Trojan horse viruses do not reproduce. 'Worms' are computer viruses that that are designed to copy themselves from one computer to another over a network. Recent viruses designed to be spread via email, e.g the 'love bug', are 'worms'. The latest computer viruses have been email viruses. Until recently you could not catch a virus by reading an email message. You were only infected if the message had an infected attachment. The 'bubbleboy' virus was the first email virus that could infect your computer simply by you reading the message. Another similar email virus is the 'kak' virus, it also embeds itself without any email attachment to every email sent from an infected system.
Your computer can become infected by a computer virus in a variety of ways:
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