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What Is Malware? Definition and 6 Examples

Paul's passion for technology and digital media goes back over 30 years. Born in the UK, he now lives in the US.

For a definition of malware plus six examples, please read on...

For a definition of malware plus six examples, please read on...

During my many years of teaching computers, from basic skills through to the more advanced use of digital media software, as well as when working with computers on a personal basis, I believe that I've encountered pretty much every kind of malicious software out there.

This article gives a definition of malware, examines six examples, and outlines three approaches that can be used to minimize or prevent being affected by malware.

Definition of Malware

Malware is malicious software that has been designed with the intention of idisrupting, corrupting, or otherwise damaging a computer system, typically through gaining unauthorized access.

6 Examples of Malware

Here are 6 malware examples:

  1. Virus
  2. Trojan
  3. Spyware
  4. Worm
  5. Adware
  6. Ransomware

I will explain each example in more detail below.

1. Virus

In computer terms, a virus is a malicious piece of code, or a program which is capable copying itself and spreading from one computer system or device to another. Viruses are usually written with the intention of having a disruptive effect on the machines that they infect, causing such issues as the destruction of data, or the corruption of the operating system.

Viruses typically work by inserting or attaching themselves to legitimate pieces of software in order to facilitate the execution of their code. The best way to protect a device from a virus is by installing anti-virus software and keeping it up-to-date.

2. Trojan

A Trojan (or Trojan horse) is a form of malware that hides its real content to trick the computer user into believing that it's a legitimate file. One common way that this deception happens is when a trojan arrives attached to an email from a trusted source. Unlike, viruses, which can activate and replicate themselves, trojans rely on the user to activate them.

Computer Trojans are named after the wooden horse that was used to sack the ancient city of Troy. The wooden horse was built and left outside the city by Greek soldiers who were besieging Troy. The horse was thought by the people of Troy (known as Trojans) to be a harmless victory trophy, so they brought it inside the city walls - but inside it were Greek soldiers who emerged at night and opened the city gates, enabling the invasion and fall of the city.

3. Spyware

This type of malware infiltrates the computer system, accessing and monitoring the user's activities, such as internet usage data and sensitive information. It then relays this personal information to advertisers, data firms, or others.

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Spyware is a threat to both businesses and individual users and is used for many purposes, such as to track and sell internet usage data, steal credit card or bank account details, or for identity theft. It does this through actions such as tracking the user's login and password information, and spying on sensitive information.

4. Worm

Worms typically use computer networks to spread themselves. They exploit weaknesses in security software, or can arrive via spam emails or instant messages. Once established, the worm can then use the host computer to scan and infect others. Worms can corrupt and delete files, or create additional malware programs on the user's computer.

All this can happen without the user knowing anything until the worm is established. Some worms do nothing but replicate themselves repeatedly, overloading the computer and network. Others will steal information, or open a back door for hackers to use.

5. Adware

As its name implies, this type of malware inundates the user with unwanted advertising. Adware programs can change the browser's homepage, bombard the screen with pop-up ads, as well as create spyware. Although this software may not sound as bad as other forms of malware, it can be extremely irritating and disruptive, and is often capable of causing your device long-term problems. It is common for this malware to slow down or even crash your device.

It can also use up your internet bandwidth. Adware is the name for this software when it infects a computer, but is known as madware when it's on a mobile device, such as a smartphone.

6. Ransomware

Ransomware is a particularly sinister form of malware that is used to extort money from users by criminals. It uses encryption to hold a user's data with the promise that the data will be restored upon payment of a ransom.

Ransomware gets onto a computer by either fooling the user into installing it, or by making use of weaknesses in the device's security software. This type of malware can target not just individual users, but also high profile institutions such as hospitals, universities, and government agencies.

How to Avoid Malware Infections

Generally speaking, there are three approaches that you should take to minimize or prevent malware infections:

  1. Make sure that you have anti-malware security software installed on your computer, and that it is updated regularly.
  2. Make sure that you use secure passwords and that you change them regularly.
  3. Do not download programs or documents from untrustworthy sources. It is also wise to be wary of attachments and hyperlinks found in spam emails and instant messages.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2020 Paul Goodman


Umesh Chandra Bhatt from Kharghar, Navi Mumbai, India on December 22, 2020:

Well explained. Thanks.

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