Of viruses and worms

Malware:
Before we start off on viruses and the like, it would be better to introduce the term ‘malware’. Mal-ware is just malicious software. Any software or program that is designed for the purpose to harm you or your computer is Malware.
Thus, viruses, worms and everything else that we will talk about are malware by definition. [Note that not all malware are viruses].

The worm and the virus:
To clarify points, this aint no children’s tale. This is rather, the tale of two legendary infectors of computer systems worldwide – the virus and the worm. There are other types of pains-in-the-neck for computer users, but they can’t compare with the magnitude of damage that these two villains have managed to inflict over the past years. [But we’ll mention them nonetheless.]
People are often confused between the virus and the worm, (and don’t even use the terms Trojan, malware and spyware :S) but they are completely different. They both cause harm to the system, and the similarity ends there.

The virus:
Ah, a great day, and you settle down for a cuppa in front of your computer listening to that favorite tune of yours. Suddenly, the music player stops functioning and you are hogged by a rather pretty pop-up that swears at you. Or an error message appears and screams out, ‘Low memory on your hard-drive’. “Hmm that is strange” you wonder… you remembered having 12 GB of space on your drive just a few hours ago.
Before you totter off to your friend claiming that he had eaten up space while you were gone, you might as well consider a virus infection on your PC. [Don’t glare at me like that].
Viruses can damage your pc in a variety of ways [and they are rather proud of it :S]. They can eat up your memory space, present audio or visual messages, delete random files and better still, fcuk up your boot-sector and render your Operating system useless.
They feature of the virus is ability to spread quickly (which gives its name). A virus can infect thousands of computer systems in the matter of minutes. They can cling onto other programs, send themselves through email, or sneak into floppy disks or CDs while they are being written.
It is also possible that a URL on the internet may be infected!! Accessing the URL from your PC will spread the virus to your system too.

The worm:
The worm is lesser known that its fast-spreading counterpart. But it is just as dangerous.
The worm doesn’t need another medium to spread itself. It can easily operate itself as a program and spread over networks. The worm is identified by the fact that is nearly always targets networks to inflict damage. It can eat up bandwidth or send messages to every IP address on the LAN. Many worms carry a program on their back(called payload) which infects every computer where the worm travels. This payload can damage the system or send valuable information to the worm’s master.
The virus makes its presence felt, but the worm carries out its orders quietly until it strikes the fatal blow. You’d probably not even notice the effects of a worm on your pc, but it could be there.

The Trojan:
The Trojan or the Trojan horse is a master of disguise. It pretends to exist as a harmless program until it is executed. Trojans mainly occur as .exe files. They may appear to be harmless games or the like, but in the background, they carry out feats of destruction.

Spyware:
Spyware is a rather controversial class of programs because a while lot of them are generated legally!!
Spyware, as the name suggests, are programs that spy on your PC. They may be harmless (sending logs of errors to the software manufacturer) or otherwise (sending your credit-card number to the spyware owner). Nonetheless, they invade our privacy which is definitely undesirable. A lot of software companies mention their in-built spyware in their terms and conditions (have you ever read that?).

As you may have noticed, there can be programs that can have characteristics of more than one of these groups. But that doesn’t stop them from being Malware.

-Cancer