Virus, malware, worm and Trojan horse

Virus, malware, worm and trojan horse

In this article, we are going to discuss Virus, malware, worm and trojan horse. It can be helpful to get a high-level understanding of all of these at the core level. Before you start looking for a solution to the problem, it’s important that you know what actually they are and how it works. The information in the below can help you beware and to protect yourself at the best level. So, let's start it -

What is a Trojan?

A Trojan is also known as Trojan horse. It is a type of malicious software developed by hackers to disguise as legitimate software to gain access to target users' systems. Users are typically tricked by some attractive social media adds who then directed to malicious website thereby loading and executing Trojans on their systems. Cyber-criminals use Trojans to spy on the victim user, gain illegal access to the system to extract sensitive data.

Functions -

  • Deleting data

  • Blocking data

  • Modifying data

  • Copying data

  • Disrupting the performance of computers or computer networks

  • Unlike computer viruses and worms, Trojans are not able to self-replicate

Example: - JS.Debeski.Trojan

What is a Virus?

An important distinction between computer viruses and worms is that viruses require an active host program or an already-infected and active operating system in order for viruses to run, cause damage and infect other executable files or documents. Viruses are typically attached to an executable file or a word document. They often spread via P2P file sharing, infected websites, and email attachment downloads. Once a virus finds its way onto your system, it will remain dormant until the infected host file or program is activated, which in turn makes the virus active enabling it to run and replicate on your system.

Types of Virus

  • File viruses

  • Boot sector viruses

  • Macro viruses

  • Script viruses

Examples of the virus are  - W32.Sfc!mod



What are Worms?

Worms are stand-alone malicious programs that can self-replicate and propagate via computer networks, without human help. Worms don't need a host program in order for them to run, self-replicate and propagate. Once a worm has made its way onto your system, usually, via a network connection or as a downloaded file, it can then make multiple copies of itself and spread via the network or internet connection infecting any inadequately-protected computers and servers on the network. Because each subsequent copy of a network worm can also self-replicate, infections can spread very rapidly via the internet and computer networks.

Types of Worms

  • Email-Worm - Files sent as email attachments

  • IM-Worm - Via a link to a web or FTP resource

  • IRC-Worm - Via a link sent in an ICQ or IRC message

  • Net-Worm - Some worms are spread as network packets

  • P2P-Worm - Via P2P (peer-to-peer) file-sharing networks

Examples of worm are: - W32.SillyFDC.BBY



What is a Malware?

The term malware is a contraction of malicious software. Put simply, malware is any piece of software that was written with the intent of doing harm to data, devices or to people. Viruses, Trojans, spyware and the like, what you're really hearing is the talk of different kinds of malware.

The popular image of the rebel hacker, testing his skills and wits against whatever system he's decided to make his challenge. But today, "black hat” software developers often sell their skills to the highest bidder. These can be criminal organizations looking for tools to operate in the digital world, or government intelligence agencies looking to access the data locked away in the computers, networks and mobile devices of their targets.

How can all these impact on you?

The type of actions that they can perform on your computer or any unprotected system -


A backdoor Trojan gives malicious users remote control over the infected computer. They enable the author to do anything they wish on the infected computer – including sending, receiving, launching and deleting files, displaying data and rebooting the computer. Backdoor Trojans are often used to unite a group of victim computers to form a botnet or zombie network that can be used for criminal purposes.


Exploits are programs that contain data or code that takes advantage of a vulnerability within application software that’s running on your computer.


Rootkits are designed to conceal certain objects or activities in your system. Often their main purpose is to prevent malicious programs being detected – in order to extend the period in which programs can run on an infected computer.

Virus, malware, or Trojan-Banker

These type of Banker programs are designed to steal your account data for online banking systems, e-payment systems, and credit or debit cards.


These programs conduct DoS (Denial of Service) attacks against a targeted web address. By sending multiple requests - from your computer and several other infected computers - the attack can overwhelm the target address… leading to a denial of service.

Virus, malware, or Trojan Downloader

These type of downloaders can download and install new versions of malicious programs onto your computer including Trojans and adware.


These programs are used by hackers in order to install Trojans and/or viruses or to prevent the detection of malicious programs. Not all antivirus programs are capable of scanning all of the components inside this type of Trojan.


FakeAV programs simulate the activity of antivirus software. They are designed to extort money from you – in return for the detection and removal of threats… even though the threats that they report are actually non-existent.


This type of program steals user account information from online gamers.

Virus, malware, or Trojan IM

These type of IM programs steal your logins and passwords for instant messaging programs - such as ICQ, MSN Messenger, AOL Instant Messenger, Yahoo Pager, Skype and many more.


This type can modify data on your computer so that your computer doesn’t run correctly or you can no longer use specific data. The criminal will only restore your computer’s performance or unblock your data after you have paid them the ransom money that they demand.


These programs can cost you money - by sending text messages from your mobile device to premium rate phone numbers.


These type of Spy programs can spy on how you’re using your computer - for example, by tracking the data you enter via your keyboard, taking screenshots or getting a list of running applications.


These programs can harvest email addresses from your computer.

Some other types of attacks include - ArcBomb, Clicker, Notifier, Proxy, PSW.

How do you protect yourself against Virus, malware, worm, trojan horse or something else?

The best practice is, to stay away from questionable sites, pirated materials, and dubious links; it may help, but in the long run, something will get through. If you truly want to stay protected, you need an anti-malware or some useful anti-virus software like Kaspersky, Quick Heal, and AVG Anti-Virus to stay protected. By installing effective anti-malware software, you can defend your devices including PCs, laptops, Macs, tablets, and smartphones. Event security experts rely on some form of protection to keep them safe.

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