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What is difference between virus worm trojan spyware

Today in iThePro we will look at “the difference between virus worm trojan spyware “, we will take a big view about this nasty programs. Some of those times, your fears might turn out to be true. Hence it helps to know about these enemies of your computer and get a basic understanding of how they work. That could help you deal with them in a faster & better way.

Waht is a Virus.

What is difference between virus worm trojan spyware - iThePro.ComBiological virus and computer virus is almost the some think, biological virus affect human and computer virus affect computers. This virus replicates itsef in the computer memory, and more than that they also afftect files,OS and even master boot records with malicious codes. So then your computer will starting slow.

There are different types of viruses, some affect the system adversely and leave it completely unusable while some are just written to annoy the user. Disabling task manager is one of the most common ways that virus creators employ to irritate users.

As a virus always needs a human action to initiate itself, in a computer most of them attach themselves to an executable .exe file because it knows eventually the user will double click on it to run it and that’s all it needs to infect the computer. Yes, unfortunately, most viruses are inadvertently initiated by the computer users themselves and hence it is important that when you install and run programs, you know beforehand that you got them from a trusted source.

What is a Worm.

computers-wormsPractically a worm is an evolved form of a virus. Like virus, worms too replicate and spread themselves but it happens on a bit larger scale. Also, unlike virus, a worm does not need a human action to replicate and spread and that’s what makes it more dangerous.

A worm always seeks for network loopholes to replicate from computer to computer and thus most common way of intrusion are emails and IM attachments.  As the infection is network-based, a good firewall along with antivirus is necessary to control worm attack. Also, this means that blindly downloading email attachments or clicking the links friends share with you in a chat window isn’t recommended. Double-check before you do that.

What is a Trojan.


Trojan horse or simply Trojan is a bit interesting. Trojan horse is a program that appears useful by pretending to do certain things in foreground, but in reality they are working silently in background with the only objective of harming your computer and/or stealing valuable information.

Let me explain this metaphorically.

Suppose you are the CEO of a company and there’s an employee in your firm you think is a valuable asset because of some initial success he gave your company. In reality the employee is working for your competitor and destroying your company from within. Now these kinds of employees can be considered as a Trojan horses if you consider the company as your computer.

Most common way to invite a Trojan horse to your computer is downloading malicious software like keys, cracks, free illegal music, wares etc from an unknown source. Thus the best way to stay away from Trojans is by making sure you install software from trusted sources.

What is a Spyware.

spybotSpywares are also malicious computer programs that can be installed on computers but unlike any of the above they don’t harm your computer in any way. Instead, they attack you!

Once installed on a system they run in background and keep on collecting user’s personal data. These data can include your credit card numbers, passwords, important files and many other personal stuff.

Spywares can track your keystrokes, scan and read your computer files, snoop IM chats and emails and God knows what else. Therefore again it’s always advisable to download and install software from trusted sources.

What is a Rootkit.

16413720-abstract-word-cloud-for-rootkit-with-related-tags-and-termsRootkits are computer programs that are designed by attackers to gain root or administrative access to your computer. Once an attacker gains admin privilege, it becomes a cakewalk for him to exploit your system.

Most often, rootkits are used to control and not to destroy. Of course, this control could be used to delete data files, but it can also be used for more nefarious purposes.

More importantly, rootkits run at the same privilege levels as most antivirus programs. This makes them that much harder to remove as the computer cannot decide on which program has a greater authority to shut down the other.

What it does do, is provide access to all your folders – both private data and system files – to a remote user who, through administrative powers, can do whatever he wants with your computer. Needless to say, every user should be aware of the threat they pose.

Rootkits generally go much deeper than the average virus. They may even infect your BIOS – the part of your computer that’s independent of the Operating System – making them harder to remove. And they may not even be Windows-specific, even Linux or Apple machines could be affected. In fact, the first rootkit ever written was for Unix!



Oussama Amri 20 years, security professional from Tunisia. Lover of computer science especially programming and secuirty. You can follow me on: