Computer Viruses

1. Computer Viruses

2. Where the name came from • This is a phrase coined from biology to describe a piece of software that behaves very much like a real virus (only it spreads from computer to computer rather than people!).

3. What is a virus? • A Computer Virus is a software program that is designed to copy itself over and over again and to attach itself to other programs. • In the early days of personal computing (1980's) some of the people who created viruses had a certain misplaced sense of humor. • For example, there was a virus that caused all the characters on screen to drop into a heap at the bottom of the display. Very annoying, but relatively harmless. • Some really nasty versions came out that were deliberately designed to corrupt and delete your files as well as trying to copy itself everywhere.

4. What is a virus? • Viruses can cause an immense amount of time wasting and financial loss for people and businesses. • For example, the "Melissa" virus was so effective in spreading itself that many huge corporations had to shut down their email systems until the virus could be contained. • It is important to understand that viruses do NOT damage the hardware. They affect the data and programs stored on your computer.

5. How do they spread? • The most common way of getting a virus these days is to open an email attachment or visit a web page which contains a virus. • Another way is to load an infected file into your computer from some kind of storage device • Floppy disk • Memory stick • CDROM • DVD • Portable Hard Drive • Note: The CD and DVD products from reputable companies are extremely unlikely to contain a virus. It is the personal 'burned' ones that are a potential problem.

6. How do they spread? • It is also possible to pick up a computer virus through 'peer to peer' file sharing networks. These are internet networks that are used by people to share files amongst each other. • There is often no immediate evidence that your computer has been infected with a virus and you might be unaware of it for a while until it causes something to go wrong. • Basically a virus is spread by allowing it to run (technical term: "execute") on your computer, so any executable file or computer program can contain a virus.

7. How can they be removed? • As computer viruses became more of a menace, companies began to develop software to detect and remove them. These were named 'anti-virus software'. • There are a number of anti-virus programs available for wiping out  viruses for example Norton, McAfee and Sophos. • When the anti-virus software recognizes a virus pattern, it will alert the user, and ask them whether they want to remove the virus and clean the system, or whether they simply want to 'quarantine' the virus.

8. Preventing Infection Viruses can be prevented by taking sensible precautions including: • Using anti-virus software to scan your system daily or weekly • Scanning all incoming e-mails • Not opening attachments from people that you don't know (or attachments which look suspicious) • Unless you are using a reputable site, not clicking on web site offers which look too good to be true, for example 'download this amazing game for free'

9. Preventing Infection Viruses can be prevented by taking sensible precautions including: • Use special filtering software to prevent automatic downloads of computer programs • Not allowing people to load applications or use floppy disks/memory sticks on your system • Not using software that has been copied • Backing up your system regularly so you can recover your data with clean copies

10. Other Pests As the internet has grown and millions of people are online, so has the development of other types of software pests. These include: • Trojan software • Worms • Adware / Spyware

11. Other Pests Trojan software • This is an application that appears to do something useful such as a computer game (which is why you loaded it on to your computer in the first place) but quietly, behind the scenes it is doing something with ill-intent. A trojan may:- • Log all your keystrokes and then send the details to a remote computer / server. Used to capture your passwords • Allow someone else to take control of your computer whilst you are online. • Capture screen shots and send them to a remote computer, once again with the intent of obtaining confidential information such as financial screen shots. .

12. Other Pests Worms • These are a bit like a computer virus but they spread on their own through computer networks. Their biggest problem is the sheer amount of computer time and bandwidth they soak up, so making the network slow to a crawl. Adware / Spyware • These are programs designed to keep track of which adverts you click on and then they send specific adverts to your browser. Fairly harmless but annoying and hard to get rid of.

13. Legislation • It is against the law to distribute a virus to others. • The law which covers this area is called The Computer Misuse Act (1990). It also covers various computer crimes such as Hacking, computer fraud as well as the deliberate spread of viruses. • This law specifies a virus as: 'unauthorised modification of the contents of a computer, impairing the operation of any program or reliability of data'. • unlimited fine and up to a five year prison sentence.