Viruses |
A virus is a special kind of computer program which (usually) has these four features :
A new class of virus called worms have started to spread across the Internet. A worm has all of the properties of a virus but is able to spread without the user doing anything. If your computer is turned on and connected to the Internet it could get a worm without you doing anything.
There is nothing mysterious about a virus. A virus is simply a program that someone has written.
A computer "catches" a virus when a floppy disk or CD-ROM containing a virus is used on the computer. The virus may be hidden at the start of the disk or CD-ROM (in the "Boot Sector") or may be hidden inside another file.
When you access the disk or CD-ROM the virus will copy itself onto your hard disk. It will do this by looking for another program on your hard disk and attaching itself to this program. The virus may make lots of copies of itself, adding itself on to the end of other files on your hard disk to hide itself. The more copies of the virus that are made the harder it will be to get rid of.
Viruses can also be caught from files loaded across a network such as a school network or the Internet. In particular a number of recent viruses have been transmitted as files attached to emails. Viruses which attach themselves to emails can spread much more quickly that viruses which spread by other methods.
A virus only spreads when the user of a computer does something such as opening a file or reading an email. Worms spread across a network without the user doing anything. They simply look for computers connected to the network and copy themselves onto these.
There are several thousand viruses. They all do slightly different things. Here are some examples of the ways in which a virus might affect a computer :
Some viruses start operating as soon as they are copied onto your hard disk. Others are only triggered by certain events. For example a virus may do nothing until a particular date is reached.
Viruses can not damage the computer’s hardware; they can not stop your monitor or printer working or break your hard disk; though they could corrupt information stored on the hard disk.
The actions that a virus will carry out are deliberately programmed by the person who created the virus. However most viruses are copied onto a computer accidentally by someone who does not realise what they are doing.
There are several steps that you can take to reduce the risk of a virus getting on to your computer. These include :
Deliberately introducing a virus onto a computer system is an offence under the Computer Misuse Act 1990 which is punishable by a prison sentence of up to five years.
You could also install a special virus checking program on your computer. A virus checker will examine any files that you use. If a file has a virus then the program will detect it and may be able to remove it. Removing the virus could damage the file that has the virus but it will stop the virus spreading. Of course new viruses are produced all of the time so you must keep you virus checker program up to date with details of all the latest viruses.
If you are worried about a virus or worm getting onto your computer over the Internet you can use a firewall to stop other computers accessing data on your computer.
Regularly backing up important data will ensure that it can be recovered if it is attacked by a virus.
GCSE ICT Companion 04 - (C) P Meakin 2004