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Trojans, Viruses, Hoaxes, Worms, Vulnerabilities and Exploits, we've all heard of them, and if you are connected to the internet are a potential target.
Symptoms can be no effect on you at all, through to losing important information and even being unable to boot up your computer.

So what are they?

Trojans - files carrying hidden malicious payloads
A Trojan refers to a program that appears as something that looks innocent and safe, but hidden inside is usually something harmful, usually a worm or a virus. Trojans often come in the guise of a game, a link or a picture via email, appearing quite harmless. Once you execute the file (run or open it), the worm or virus gets to work. It may just do things to annoy you, or more usually a worm or virus will cause damage to your system.

Viruses - computer programs designed to cause trouble to your computer
Viruses are computer programs with the sole purpose of manipulating or destroying data on our computers. The virus may affect your documents or the files needed to run the system. A virus can cause an infected computer to do strange things on specific dates, and may even damage your registry file rendering the machine unbootable.
Viruses are transferred through executable files you may have got from a friend, downloaded from the net, or installed through a floppy disk or CD. A virus may often come buried inside a Trojan, which is the carrier for the virus.

Anti-virus programs will search the files on your disk and by email to detect known viruses. Because there are new viruses regularly being developed it is impossible to be 100% safe, but any defence is better than none at all.
There are lots of free anti-virus programs available and a quick search of the internet will reveal most of them.
Having installed an anti-virus program you must keep the definition file up to date, otherwise you will become open to any new viruses that may come around. The antivirus program should have an option to update automatically, switch this on. New definition files are usually issued about once a week.

Worms - actively replicate themselves
Worms operate differently. Do you remember how living cells split and double, split and double...Worms act much the same way.
Worms often come through on email, but people can also get infected if they accept a Trojan which has as the worm buried inside it. If you receive a worm through your email, and open (execute) it, then it will probably send itself out to everyone in your address book. The speed of spread of a worm of this type is incredible, infecting up to thousands of people in a singe hour.
Some worms will send an email to everyone listed in your email address book and then delete itself leaving you with no idea that anything untoward has even happened!

Vulnerabilities and Exploits
The operating system (O/S) (usually Windows or Linux), provides a means for running programs on a computer. The O/S's are not perfect and can have vulnerable areas which can be exploited by the unscrupulous hacker. Keep an eye on your O/S support site for security patches to improve your security.

What about Firewalls?
Before computers, a firewall was an area of open land between, for example, forests and houses, and even a strip between the middle of the forest. The purpose is that if a fire were to break out, it's spread would limited as it would not be able to cross the firewall.
In simple terms, in the same way a computer firewall is there to stop certain traffic crossing from outside your computer to inside it.
There are people out there who love to be clever and gain access to you computer, and the internet provides a perfect opportunity for them to do so (esp. if you are on Broadband).
Every computer connected to the internet has an address (called the IP Address) and once a hacker finds a valid IP address he can then use the tools at his disposal to try and gain entry to the computer at that address. Without a firewall, anybody testing your IP address will get a response that you are there. With a firewall no such response will be given, the tester (hacker!) will then move on and search for another address and so on.
(A bit like a burglar walking past houses with burglar alarms until he finds one that hasn't got one. Although in our case the houses with burglar alarms will not even appear to exist!)
There are internet sites that will test your firewall for you, a couple are listed here: HackerWatch, Symantec or (Shields UP)

What To Do About It:
The following guidelines should help keep you safe.
  • Never accept files from anyone you don't know
  • When downloading files off the Internet, be sure it's from a reputable site.
  • Never run or open files you receive via email from people you don't know. If you have any doubts at all, email the sender for clarification.
  • Install a Virus Detection program.
  • Keep your anti-virus definition file up to date
  • Install a firewall. Again there are many free products available on the internet.
  • Better safe than sorry!

A useful site for finding free software is FreeWareFiles, click on Internet Tools and then Internet Privacy/Security for quite a list of available utilities.

Why are they free? How can thay be as good as paid for versions?
Good questions. In my case I started out with ZoneAlarm firewall and AVG anti-virus, both available to download freely. Unable to find a good free parental controls product, I opted for Zonealarm Pro (see, because I liked their free product, I chose to purchase a better product from them). As time went by ZoneAlarm Pro became ZoneAlarm Internet Security which included Anti-Virus and a host of other security measures.
If the original free product had been no good I would not have opted to buy anything from them, ever!
Thank you for an interesting article , Ade!
Have only just read this - a very big thank you for the article - many of us take to much for granted.
Thanks, Very Helpfull!
added the link to
Thanks, very useful information. All us Saffers need to safeguard/protect the important info on our PCs.