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About Viruses

What are they?

It is a sad fact of life that there are people out there who like to prove how clever they are and spend their time creating virus programs.

A virus is a piece of code, embedded within another piece of code such as a program so that when the program is run, the virus is also run. The main property of a virus is to infect other programs and it will seek out programs to infect on your computer, over your network or over the internet. An additional feature which may be present in a virus is known as its "payload". This is the action it takes when it "goes off". For example it may be designed so that on a particular date (eg. any Friday 13th) it will display a silly message on your screen. Alternatively it may start deleting files from your system! On the other hand, it may do absolutely nothing at all.

How do they get here?

Modern viruses are more often than not sent by email and one of the first things they do when they arrive is to switch off anti-virus programs so they will not be detected! They will also disguise themselves by changing who they came from to an email address they found on a computer. About the only thing you can tell from the email 'from' field is that it almost certainly did not come from them!

In August 2003 a virus known as Blaster was released and this did not use email to get around, it simply looked for computers in the internet and found "holes" it could get through and so plant itself on the vulnerable computer.

So how bad are they?

Having said all this, viruses are a cause for diligence and not for panic. They will rarely do anything unfixable to a home computer and more often than not are just a nuisance. Remember that in order for them to spread the computer needs to be able to run! By the time it's set to deliver its payload (if any) you should have found it with your anti virus program.

If you think you’ve been infected, don’t panic, just Call on Ken!

How do you know if you're infected?

So how do you know if you’ve been infected? Other than a virus scanner, there’s no real way but a few clues may be emails arriving from someone you know, that don’t seem to make sense; “why are they telling me this?”. Perhaps your email connections are taking longer than they should or maybe your emails are being returned saying they’ve got a virus! All these are clues.


A firewall is a device or, more commonly for home users, a piece of software which sits monitoring your internet connection and stops people outside getting in to your computer.

Although most viruses are spread by email, this is not always the case and Blaster and Sasser infect computers directly. With a firewall in place on these machines, they are not able to do this.

[Techie bit: Sasser takes advantage of a vulnerability in unpatched versions of Windows XP and Windows 2000 systems. The worm infects vulnerable systems by establishing a remote connection to the targeted computer, installing a File Transfer Protocol (FTP) server and then downloading themselves to the new host.]

Windows XP actually comes with a primitive firewall built in but it doesn't get switched on by default in the earlier XP service packs! To see if it is running from the Start button, select Control Panel and the select Network and Internet Connections. From there select Network Connections and click on the connection you use to access the internet. In the details panel on the left, if the firewall is on, it will say so but it is less than obvious so right click on the connection and select properties. In the window that appears, select the advanced tab (don't worry, it's not all that advanced!) and you'll find you can check on or off the firewall.

Of course, an even better solution is to use a better firewall and there are a number of free products available for home use. These have the additional advantage of protecting you from rogue software sending information out from your machine.


It is essential that all computers which connect to the internet (even if only for email) have the protection of an anti virus package. This sits in the background and prevents viruses getting onto your machine by email, infected files or any other means.

An excellent free product is produced by Grisoft and called AVG and it is available for download from or alternatively you can ask Ken to install it and provide instruction in its use.

In order that any package can provide proper protection, it must be kept up to date and its method for achieving this varies between packages.

In the case of AVG, the manual way is to run the control centre (double click on its icon which is a square of small yellow, black, green and red squares) and select the Update Manager tab. While you are dialled in to the internet, press the Update Now button. If there is anything new to download, it will update your system for you.

How often you update your scanner depends on you. Have a look at the virus list following and see how often new ones are found. you aren't protected against a new virus until you update your scanner! This process should be done at least on a weekly basis though ideally you should do it every time you dial-in, just to be on the safe side.

Virus Lists

Very many viruses are continually getting released and some have gained a certain notoriety. These include Blaster, Netsky, Bagle, Sasser and MyDoom but this is only the tip of the iceberg. Several hundred new viruses are discovered each month!

When was your virus scanner last updated?

If you want details of specific viruses, most of the anti virus software providers have lists on their web sites, for example,