Worms - the very word conjures up images of snotty-nosed urchins scratching at their trouser seats, doesn't it? Or at least slimy things wiggling in the compost. What place could worms possibly have in the sterile world of computing?

The 3 common types of malware i.e. malicious software, are viruses, Trojans and worms. Worms are the deadliest as they can function without any human involvement. Similar to viruses, worms also have capability to replicate themselves. However, worms are self contained, in that they do not use a host program for propagation the way viruses do.

Worms more commonly affect computer networks than individual machines. Networks are the big complicated groups of technology consisting of servers, routers and client machines. You might think this makes your home PC immune to worms, but remember the internet is basically a large network of computer networks, it is very much susceptible to worm attacks. If your PC is connected to the internet, which it must be if you are reading this article, then you need to know about worms.

Worms can cause damage similar to viruses, for example deletion of files, corruption of programs, and so on. Once released into a network, worms can replicate by themselves and hog the CPU time of servers and routers, leaving little time for other programs to run. This leaves the network continuously busy and slows down network traffic.

Servers are powerful PCs with large storage capacity and store common resources that are shared by other PCs or clients in the network. Routers are used for routing network traffic and are nothing but specialized servers with customized operating system.

It is not the worm itself that is the only cause for concern. Worms can carry other types of malware with them. These are referred to as "payloads". For example, a payload could be spyware which secretly monitors the activities of the computer, or it could be back door installation programs which act as hidden access points in the network and can be used to send spam or steal data or programs from the computer.

The worm's payload can cause considerable damage to a computer in a network by switching off antivirus functions, opening up computer ports, and other violations of security. Opening ports can allow data to be transferred to computers outside the network, for example, or allow a hacker to delete files stealthily.

Getting Rid Of Worms

Firewalls are designed to control network traffic and can act as shield to computers in the network by effectively cloaking them. They are reasonably effective in saving computers from worm attacks. Even home computers can easily be protected by a firewall - mine is, and I'm sure you now appreciate why!

However, worms can also be distributed through emails as attachments, just like viruses. You should be extremely careful when opening mail from unknown sources or unexpected files from a known source.

You should always make sure you are running up-to-date antivirus protection software.

Despite all precautions, worms may get into your system. Symptoms include slowing down of internet access, automatic reboots or sluggishness of the system. If you notice any of these symptoms, scan the computer immediately with antivirus software.

If antivirus software does not restore your computer to normal, consult an online manual, webmaster forum, or real world PC expert.

Drawings by psd, photo by Editor B.