Viruses

A virus is simply a program designed to cause harm to someone else's computer. A virus spreads by duplicating and attaching itself to other files. The extent of the damage depends on the virus. There are tens of thousands of viruses.

Some virus damage is insignificant but inconvenient. Some virus damage is disastrous, putting the computer system out of action by crashing memory, erasing files or corrupting data.

How do you catch a virus?

Viruses are written by malicious programmers who wish to cause problems to other computer users.

The primary source of infection these days are e-mail attachments followed by illegal software and infected files from the Internet. Also, by putting an infected floppy disk into your computer - the virus can automatically copy itself from the infected disk into your computer

If you have up to date anti virus software installed this will immediately warn you of any infection. If not, there is usually no evidence of the virus and the user is not usually aware of it until something goes wrong.

How can they be prevented?



Viruses can be prevented by taking sensible precautions, including:

• using up to date anti virus software. E-mail attachments are now the biggest source of virus
• spread and many e-mail servers are now installed with anti-virus software.
• not allowing other users to use their own floppy disks on your system
• not allowing users to take the company's disks home to use on their own PC
• only downloading files from reputable Internet sites
• write-protecting disks
• avoiding software from unreliable sources
• backing up data regularly

Anti-virus software can inspect computer files and e-mail attachments for viruses and remove or quarantine any which are found.

Other problems

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. 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 screenshots and send them to a remote computer, once again with the intent of obtaining confidential information such as financial screenshots.

Worms. These are a bit like a computer virus but they spread on their own through compuer 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.

The Computer Misuse Act

The Computer Misuse Act (1990) made three new offences:

1. accessing computer material without permission e.g. looking at someone else's files
2. accessing computer material without permission with intent to commit further criminal offences e.g. hacking into the bank's computer and increasing the amount in your account
3. altering computer material without permission e.g. writing a virus to destroy someone else's data

Writing a virus or deliberately spreading one is illegal.