Anti Virus

What is a Virus, a Worm and a Trojan

To understand what an anti virus is, it's probably worth noting what a virus is. A virus is a program that, without interaction of the user, runs by its self in oder to cause disruption to a computer. Like with a virus in the human body which infects other areas, it will infect other files on the computer, so that it will run when you run other programs. Viruses may just be annoying, pop up messages, shut down your pc etc..., they may also cause damage, such as deletion of data, or infecting special areas of a hard drive.

A worm is a program or similar that, also without interaction of the user, spreads from computer to computer. They are often inside files like viruses but not always, recent worms can enter a computer through holes in the Operating System

A trojan horse usually listens on a computer for some actions, and then will do something the user will not want. Trojans will exist as part of a program that to the user looks legitimate, but they will often open up your system to an exploit, such as listening for remote connections, or they may build patterns on the user, or log keystrokes, many trojans exist that steal passwords for example.

Most of the above require the user to unknowingly download or transfer the file for themselves. This could be downloading an attachment you believe is safe or downloading a document/attachment from another infected user. Trojans will not spread accross your system or into others, viruses will infect other files in your system, worms will generally infect system to system.

What is an Anti-Virus

An Anti-Virus program is here to protect you! It'll probably work in two ways.

Firstly, it will install a shield or guard. This constantly checks files on your computer as you use them. For example, if you open the file winword.exe it will know this, and check winword.exe is not a virus. If it is, it will warn you and forbid access until you advice on further action.

Secondly, it will have a scanner. You can tell it to scan your whole system, it will look at each file in turn, recursively traversing directories and drives looking for, and reporting any known viruses.

In addition, some of the commercial virus scanners will do more. Many commercial offerings will scan e-mail attachments and e-mails as they are received. They will also scan adverts(why?), webpages, java applets, and downloads.
It's common also for many anti-virus products to include ad-blocking, pop-up blocking and script blocking.

What should I use?

The paragraphs above note the difference between what you get in a free as opposed to commercial software.
Free virus scanners are, obviously, free, but usually only for personal use on on desktop computer.
Commercial scanners, such as McAffee and Norton, usually cost around £20-£30($30-$40).
There are also online scanners, but you should not use these as your main form of protection. There will scan your PC on request, but are generally slower as they have to be downloaded, and will often require specific browser technologies.

I personally use AntiVir personal addition, a free anti virus program from a German Company.
I chose this because it doesn't use many resources, it's friendly even with Windows 95, and it has generally detected more bad files on my computer than others have, including commercial software.
AntiVir will detect Viruses, Worms and many Trojans including third party diallers, it will also detect many forms of spyware.
Below I will show you how you can download, install and setup AntiVir personal edition.

Updating is as Important as Installing

Having a virus scanner means nothing if you don't keep it upto date. New viruses are being produced all the time, virus authors write them to avoid detection, and the only way your virus scanner will find them, is if it knows about them!
By update, I don't mean to go the shop and spend another £20 on the latest version, nor do I mean spending time downloading the latest interface. I mean you update the definitions, this should be free even in commercial software. Check for, and download updates at least once a week to ensure full protection. There will be tools for doing this updates within the anti virus program.

Downloading & Installing AntiVir personal edition.

The English version may be obtained at: http://www.free-av.com/.
The German version may be obtained at: http://www.free-av.de/.
To start downloading, simply click on the logo on their site, as shown to the right here.

Installing the product is like installing many Windows Programs. Click the "Setup" button, and then simply follow the instructions!
If it asks you to restart, you must do so, otherwise you are not yet protected.

Post-Installation

After Installation, and if necessary, the reboot, AntiVir will automatically start and you will see something like towards the right; this screen will also appear each time you start the ant-vir main program.

As can be seen:

• It will scan the memory - where it may find viruses running.
• It will scan the master boot record - an important area of the hard disk drive containing important information about its structure.
• Boot Record - an important area of a disk containing Operating System information.
• System Files - Important files required by your system.

Hopefully these tests will be clean, if not, it will allow you to delete files.

Performing a full scan

It will now ask you to perform a full scan, or you should do one anyway. This will scan all files on the system it believes can be infected with a virus/worm/trojan etc...

To start, place a tick by each each drive you wish to scan:
a:\ is usually a floppy disk drive.
c:\ is the main hard disk drive that contains the Operating System.
d:\ is usually a CD-Rom Drive or Second Hard Drive.
e:\ is usually a CD-Writer Drive or CD-Rom drive.
You will usually have at least a:\ c:\ d:\.

If you are scanning for the first time, you are concerned just with your PC, so tick just the hard drives. If you are worried about a disk you have received from somebody, or maybe a CD/DVD you've received, you can tick these and scan those. Please note, Diskettes and Optical Media (discs) take longer to scan than Hard Disk Drives.

Once you are happy, click the magnifying glass to start the scan!

The Scan

The scan screen contains information relevant to you.

• Last Detection - Last Virus Detected.
• Number of Files - Number of files Scanned.
• Time - Time elapsed since the start.
• Alerts - How many virus alerts it has presented you with.
• Repaired - Infections it has repaired.
• Deleted - Infected files it has deleted.
• Folder - The current folder being Scanned.
• File - The file being scanned.
• Status - Status is what its doing. Scanning - Scanning the file. Unpacking - Unpacking an archive.

The scan will run til completion. Hopefully it will find nothing, but in the event it does, you will see a screen like below.

To Delete or To Repair

Remember I said at the beginning, Viruses spread in to other files, worms spread from computer to computer. What this means is that a legitimate file could have viral code embedded within it. In this case, AntiVir will ask you if you want to repair the file, if it can. This means the original file will be useable, and the viral code will be removed.
A worm on the other hand doesn't usually infect another program, but is a program all of its own. In this case, and with trojans, the sensible choice is to delete.

Keeping AntiVir up to date

Like I said, keeping your anti virus up to date is as important as having one, it can only detect viruses it knows about! I would recommend updating as often as your bandwidth permits, and at least once per week.

Open the AntiVir shield from the icon in the system tray.
On the File menu, click Start Internet Update.
Click on the "Start" button and it will check file versions.
If there are updates, permit it to update.
After it's updated, the AntiVir shield will immediately restart.