Viruses

Viruses are small bits of software which get on to your computer.

They are called viruses because like the flu in humans they can spread from one computer to another.

They do this by copying themselves to new files and computers.

Different types

We often give a whole range of different malicious software the title of 'virus', but it isn't always strictly true because they don't all self-duplicate.

There are a whole variety of nasty bits of code mistakenly called viruses. They all cause problems to innocent computer users, so here are some of their names and brief descriptions, so you know what to look for.

A 'logic bomb' waits on your computer and then causes damage to it when triggered by an event like a specific time or date - like the Millennium Bug happening on New Year's Eve 1999.

A 'file virus' uses program files to get in to your computer and then it copies itself.

A 'worm' does not damage files, but copies itself endlessly across computer networks and the internet which slows them down and frustrates computer users.

A 'boot sector virus' damages the specific files that your computer needs to start up.

A 'macro virus' infects your computer by using special codes found in word processing and spreadsheet files.

A 'Trojan horse' is a malicious computer code that pretends to be a game or other interesting program that damages your PC as soon as you open it.

Spotting the symptoms

Computer viruses cause symptoms on your computer that you can recognise just like symptoms of viral infections in real life. Here are some examples:

If your hard disk or floppy disk seem to be working over time to do simple tasks, or when they should be idle, you could have a virus.

If new or regularly used floppy disks becomes unusable then they could be infected with a virus.

If your computer is operating slower than normal, this could also be a sign that a virus has got in.

If you cannot open a computer program, or if a program shuts down on its own, then this could mean that a virus is preventing it from working properly.

Unusual error messages that pop-up on your screen can also indicate a problem with a virus. To check if this is genuine or a virus, it is always worth copying the error into a search engine to find advice for experts on the internet.

Unusually slow download speeds can also indicate that the software running your connection has been infected.

A virus could also be responsible for any strange screen activity that might be happening.

How viruses are spread

One of the worst symptoms of a virus attack is when it damages your computer files. Nothing is worse than finding an important document has been corrupted.

Knowing how viruses spread and how people get into your computer is the key to protecting yourself.

Viruses can spread via a range of different ways from 'software holes' to 'e-mail attachments', 'hackers' and 'unusual boxes'.

Software holes

Sometimes programs on your computer's main software can have faults in them. These software faults or 'holes' can let viruses into the system.

The best defence against this is to have up-to-date anti-virus software.

Anti-virus software can identify viruses and destroy them as they try to enter your computer.

The anti-virus software can automatically download the latest information on how to protect you over the internet. And most professional software will ask you to download 'updates' or 'patches' to repair faults.

You should regularly update or patch your software to keep your computer as well protected as possible.

E-mail attachments

E-mail attachments are a major cause of viruses.

When you receive an e-mail attachment - a file attached to an e-mail message - never open it unless you are expecting to receive the file.

This is important because even attachments from people you know could contain viruses that can wipe out your files. If you're not sure what the attachment is then just delete it.

If you do need to open an attachment that you are not expecting, then make sure your anti-virus software is
up-to-date.

If in doubt, phone the person who e-mailed the attachment and ask them what they sent you. Some viruses can send attachments without the sender knowing.

Hackers

Hackers are people that try to get into your computer.

Sometimes they try to break in to damage your files or get personal information.

The best defence against hacking is a 'firewall' which can stop unauthorised access.

At its simplest, a firewall stops anything you don't know about passing between your computer and the internet.

Most new computers will provide you with an easy-to-install firewall, but ask the company that makes your anti-virus software and they should be able to help.

Remember that you can control exactly what does and does not get through your firewall.

Unusual boxes

Sometimes boxes that you don't expect may appear on the screen asking you to install or download something.

If you don't expect it always click 'Cancel'.

If in doubt, click 'Cancel' and check on a search engine to see if this is a common virus problem or a genuine
software update.

For ultimate protection from viruses you should try and regularly update all your protection software and be vigilant for e-mail messages and files that you're unsure of.

The inconvenience of deleting a harmless file is much less than the trouble caused by opening up a file
containing a virus.