What are Virus, Trojan, Worm, Malware etc?

By -

I’m sure that, you would come across the words like  Virus, Trojan Horse, Computer Worm, Rootkit, Spyware,  adware, scareware, crimeware etc. But many of us not sure what exactly mean by each of them. We often use these words referring to something else.

malwareFirst I thought of writing about the differences between Virus and Trojan to my difference between site. Later my research revealed some more interesting facts. I observed that people often confused with all these. So I thought making clear about them to my tech blog.

Note : All these belongs to malware, which mean by malicious software. These virus, horse, worm etc are 100% computer programmed code / tiny softwares that runs on computer and they are NOT BIOLOGICAL LIVING BEINGs. Virus, Worm etc are biologically doesn’t exist.

Computer Virus :

Computer Virus are small programs. Usually they are self-executable tiny apps, which rapidly grows by themselves. The behaviour of replicating themselves without user interaction and knowledge, bought them name the virus, which is similar to a biological virus. Viruses are usually spread from one comuter to another through a portable devices like floppy disks (in older days), USB pen drives or in any other form of contact.

The intention of writing virus depends on the author. Usually there are written to  delete user files n folders, copying a file to each and every folder, attach itself to a spreadsheet or an email and thus it can enter another computer when it is transmitted.

Trojan Horse :

trojan horseTrojan is the most concentrated malware by the attackers these days. The name Trojan Horse came from an old greek tale, where warriors hided behind a horse dolls in a war.

Unlike Viruses, a trojan do not attempt to replicate iteself. Instead it sits hidden in the computer (like how the warriors use to hide inside) and does malicious activity without the knowledge of the user . Usually a trojan will be written with the purpose spying an user, watch infected computer’s screen, upload & download malicious data to a remote server, crashing the computer, taking remote control over victim’s computer, steal user bank credential and do online transactions etc.

Computer Worm :

Computer Worms are similar to Virus, except they typically  spread to un-infected computer through networks. A computer virus spread by attaching to an existing program. But a worm is standalone program that spreads  rapidly through the loop-holes of a network. Almost all worms alway cause harm atleast byconsuming  network bandwidth.

Most worms are written with the intension to spread and they usually do not attempt modifiy data on the computer. They are targetted to affect bandwidth by increasing the network traffic, creating attacker’s own bot netwhich could used for email spamming or DoS (Denial of Service – Where thousands/lakhs of such worms are targetted to access a particular website and the website can go down once the web server can not handle any more requests).

Spyware :

Spyware, as the name suggests, used for spying on someone or an organization. It keeps on sending information about the victim to it’s creator. This can be used from physically locate the infected user to stealing credentials such as password and credit card details. Spywares are mostly classified into System Monitors, Trojans, Adware and Tracking Cookies.

Adware :

Adware serves advertisements on infected system. It is created either to generate revenue to it’s boss or to render specific advertisement/link to malicious location, which in turn can harm the computer.

Rootkit :

3321596621_6b747f9e36_zA Rootkit hides a process or program from normal methods of detection. The term rootkit is a concatenation of “root” (the traditional name of the privileged account on Unix operating systems) and the word “kit” (which refers to the software components that implement the tool).

Rootkit are loaded at the time system bootup, i.e. even before your OS starts! So it very difficult to detect a rootkit. There some deadly rootkit which could hide inside OS Kernal (Kernal – Core of an Operating System) and requires OS reinstall or physical replacements of the devices in worst case..!!

Rootkits are intended to installation of programms, run hidden processes, create user accounts with full admin access etc.

Ransomware :

Once your computer is infected by a Ransomware (also called cryptoviruses, cryptotrojans, cryptoworms or scareware), you will be restricted to access your own machine and you will be asked to pay ransom money to it’s creator inorder release the computer. Some ransomware encrypts all the files in the computer and makes them no use to the infected user while other simply lock the computer. In most cases, even if the victim pays the said money to attacker, they leaves you without unlocking your computer..!!

Usually it is impossible to unlock the ransomware infected computer for an average user but a skilled ethical hacker can help you to get your computer back.


Believes strongly in "Love what you do and Do ONLY what you love" :). Simple & Straight. Will bend whenever required. Thinks everything in technology, with technology and in most cases only Technology.. :p Laziest guy, one could ever find. If he is not sitting in front of his computer, then he must be riding on his bike, of course, not both at the same time. :p Know more about Pavan

1 Comment to What are Virus, Trojan, Worm, Malware etc?

Leave a Reply

Your email address will not be published. Required fields are marked *

8 + 1 =

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>