What is Malware? Definition, Types, Prevention & Examples

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What is Malware

While there are many terms for it – we’re often confused about what malware is. Malware is a shorthand term used to describe a group of malicious software such as viruses, ransomware, and spyware. 

Cybercriminals create and use malware of different kinds to damage victims’ computers, encrypt or corrupt the data within them or gain unauthorized access into a network. Usually, malware infects systems when a link containing them is clicked or when a malicious file disguised as a harmless application is run. 

Although the concept of a virus was envisioned by renowned mathematician John von Neumann in the 1940s, it took another 30 years for the first computer virus to see the light of day with the Creeper virus of the 70s.

What Is A Malware Attack?

The Creeper virus, which simply displayed the enigmatic message ‘I’m the creeper, catch me if you can!’, was an experimental endeavor by researchers. But modern malware attacks are far more sinister and capable of permanently damaging computers and networks, corrupting or stealing sensitive data, or even encrypting data behind a paywall. 

No device or operating system is fully immune to the risk of a malware attack. Cybercriminals usually launch malware attacks for financial gain, but they can do anything once they gain access to your computer and the data within it. Some forms of malware even grant cybercriminals access to live feeds of cameras and microphones. 

Every device connected to the internet, right from your phone and computer to your smart appliances, is vulnerable to malware attacks. Following proper cybersecurity protocol while using your devices can help safeguard against malware attacks. 

Let’s look at the different kinds of malware:

Types of Malware


  • Virus

As its name might suggest, a computer virus is similar to a biological virus and spreads from one host to another. Its self-replicating abilities make it one of the most common types of malware to infect computers. Viruses require a host file such as a document or application to carry out their attack.  

Viruses typically hijack programs that support macros to execute their malicious code. Often, viruses destroy or permanently damage the victim computer’s data and can quickly spread to every other device on the network.

  • Ransomware

Ransomware has gained notoriety over the past couple of years due to its ability to encrypt victims’ data behind a paywall. 

The victim must pay several hundred or thousand dollars to cybercriminals within a time frame using untraceable cryptocurrency to regain access to their data. If they do not pony up, all the data is permanently deleted and possibly used by cybercriminals for other sinister purposes.

  • Spyware

Spyware is a kind of malicious software designed to covertly operate in the background to steal your sensitive data and transmit it to cybercriminals without your knowledge. 

Usually, spyware is used to steal financial data such as banking credentials as well as relay your internet activity to advertising firms. It can also discreetly steal sensitive login information.

  • Trojans

Much like the fable of the Trojan Horse of Troy, Trojans are malware that masquerades as legitimate software. Cybercriminals make use of social engineering techniques to get users to download seemingly harmless software. 

This acts as a backdoor for the Trojan that gains access to the system and can delete, modify, corrupt your data, or even severely impact the performance of computers and networks.

  • Worms

Computer worms or simply worms are malware that takes advantage of vulnerabilities in software to modify or delete files. Often, worms simply self-replicate several thousands of times quickly to deplete system resources and hijack the computer. 

Worms work in the background and discretely attack systems once the malicious software has been downloaded from malevolent links in spam emails or instant messages.

  • Botnets

A botnet is a large coordinated network of computers hijacked by cybercriminals to control computers and harness their computing power to take down large servers and networks. 

It works by installing malicious software onto the victim computer, enabling it to add the victim’s computer to the botnet.

  • Adware

Adware is among the most common types of malware that many users, unaware of its dangers, end up ignoring as just a normal ad. Adware will bog your computer down with several pop-up ads, causing it to slow down over time and perform poorly. 

While adware might not be as malicious as some other types of malware, it is something to keep an eye out for. Getting rid of adware can improve your computer’s performance by a good measure. The adware usually comes bundled with non-problematic software to sneak it into your computer.

  • Rootkit

A rootkit is a malicious software that cybercriminals use to gain unhindered administrator-level access to a computer. The rootkit actively works to conceal itself to avoid being detected and ensures continued backdoor access to the computer. 

Rootkits can make changes to log files, registry keys, and other system configuration-related settings that could prove fatal for your computer. With admin access, cybercriminals can access all data, including live streams from cameras and microphones.

  • Fileless Malware

While most other forms of malware rely on being concealed within another file or program, fileless malware does not require a host file to be downloaded or executed by the victim. Instead, this kind of malware hijacks legitimate scripts that are part of legitimate programs. 

Even well-reputed and trusted programs, such as Microsoft PowerShell’s scripts, have fallen prey to fileless malware. It is difficult to detect due to its memory-based nature, in contrast to most other malware types that are file-based.

Malware Protection: How to Prevent Malware

We live in a world that’s ever-connected to the internet, which is now an integral part of our lives. Vulnerability to malware is a major concern for anybody that is connected to the internet. 

In a world where intelligent, smart devices live alongside us, this is a valid concern. Taking malware protection seriously is more important than ever. 

Here’s how to prevent malware and safeguard your devices and networks: 

  • Install an Anti-Virus Program

Installing an anti-virus program is a crucial part of a good cybersecurity protocol. Anti-virus programs are companions for your devices that stay alert and look for any malware that might be trying to infiltrate your computer. 

By installing anti-virus on your devices like your computer, phone, and tablet, you can nip the problem in the bud and avoid the hassles of having your data corrupted or stolen by cybercriminals. 

Here is a comparison of Avast Anti-Virus Programs that provide the best security and ensure that you’re protected against all kinds of malware:

Your Protection, Your Way
Avast Premium Security [Single Device]
Avast Premium Security [Multi-Device]
Avast Ultimate Suite [Single Device]
Avast Ultimate Suite [Multi-Device]

Block Viruses and Other Malware

[Detect viruses, ransomware, and other threats in real-time.]

Lock Out Hackers with An Advanced Firewall, Webcam, and Remote Access Shield

[Keep hackers from sneaking onto your PC and stealing your sensitive data.]

Install on All Your Devices

[Advanced total protection for up to 10 devices (PC, Mac, Android, and iOS).]

Includes Avast Cleanup Premium

[Remove hidden junk, free up disk space, and speed up your devices.]

Includes Avast SecureLine VPN

[Encrypt your internet connection for safe and private browsing.]
  Buy Now Buy Now Buy Now Buy Now


  • Double Check Your Downloads

Downloading malicious files are one of the most common entry points for malware. Often, malicious code is disguised as a legitimate program to trick users into downloading them and having their computers infected with viruses and other kinds of malware. 

Ensuring that you’re downloading trusted programs from their official domains can reduce your risk of exposure to many malware attacks. 

  • Be Careful During Browsing 

Simply browsing the internet can be a risky affair when there is so much malicious code floating around the internet. As such, you must be careful about the websites you visit and what information you give them. Make sure that you’re only visiting trusted websites with a good amount of traffic. 

You can ensure that you’re on a safe website by checking for the HTTPS certificate. Being careful about what you browse on the internet is a primary aspect of digital health and hygiene. 

  • Protect Your Devices

It is important to protect all your devices from cybercriminals by following a basic digital wellness protocol that includes:

  • Downloading and keeping your anti-virus databases updated
  • Ensuring that you don’t download anything from non-trusted websites
  • Only using trusted software that is signed and published by a reputed company
  • Not clicking on spam emails
  • Using safe and secure passwords that are not repetitive
  • Install Ad-Blocker

Pop-ups are not only troublesome but can also automatically download harmful malware onto your devices. Installing an ad-blocker will block ads across all websites, allowing you to focus on the content you want to consume without the clutter of ads. 

Ad-blockers will also deal with the nuisance of adware related pop-ups that might be bogging your system down and feeding off its resources. 

A Few Notable Examples of Malware Attacks


  • Ransomware: CovidLock

CovidLock is an example of ransomware that infected Android phones and locked their data behind a paywall. 

The cybercriminals created a fake website that posed as a coronavirus tracker and had victims install an app from this website onto their phone. This gave them access to the phone, allowing them to encrypt the data and ask for a ransom in BitCoin. This is a recent example that shows that even mobile devices are vulnerable to malware attacks.

  • Trojan: Emotet

Emotet is a Trojan that was designed to steal banking-related sensitive information. It was first identified in 2014 and is usually delivered via spam emails. Like other trojans, it was disguised in a macro-enabled document or script. 

Emotet-containing emails used the branding of legitimate brands in its emails to pose as a regular email while it tunnelled into the backdoors of the user’s computer to gain unauthorized access. 

Emotet uses C&C servers to receive updates on the fly, without needing intervention from the user, similar to how your PC installs system updates. This makes Emotet hard to detect and quarantine. 

  • Worm: Stuxnet

Stuxnet is the name given to a complex worm that exploits zero-day vulnerabilities on Windows. Stuxnet was specifically designed to target computer networks involved in the enrichment of uranium, used for nuclear power generation. 

The virus targeted computers connected to programmable logic controllers that are used to control uranium centrifuges. The centrifuges spun too quickly and destroyed delicate equipment. 

  • Virus: Melissa

Melissa is a virus that hijacked the macros in the Microsoft Word programs to infect computers. It was disguised in a document that was purported to contain passwords to paid adult content. 

Several email servers were overloaded and brought internet traffic in some areas to a standstill. The virus was estimated to have caused over $80 million in damages until cybersecurity researchers at the FBI intervened.


With hundreds of threats to your computers and data looming all over the internet, proper cybersecurity protocol must be followed. Most malware on the internet requires you to download a malicious file or run a malicious script to gain access to your device. 

This problem is easily solved by installing a reliable anti-virus program like Avast to prevent you from accessing or downloading malicious files. Its malware databases are constantly kept up-to-date to stay a step ahead of the cybercriminals. 

Malware Protection FAQs


How do you detect malware?

Depending on the type of malware, there can be different kinds of symptoms that you look out for. Adware is very obvious and will show you several pop-ups. Other malware like trojans and spyware work discretely and can be hard to detect manually. 

Installing an anti-virus like Avast can help you detect, quarantine, and prevent any malware from attacking your devices. 

How do I remove malware?

Due to malware’s self-replicating and discrete nature, it is usually a herculean task to try and remove malware manually. A better alternative is to install an anti-virus program that would remove all viruses from your devices on its own. 

A good anti-virus program will have a database of malware that is regularly updated and prevents any possible malicious code from making its way onto your computer. 

How do I know if my phone has malware?

There is a rise in the number of malware affecting mobile operating systems like Android. A sizeable number of people access the internet from their mobile devices and don’t realize that they are vulnerable to malware attacks on their phones. 

Installing a reliable anti-virus program for your phone can help safeguard your phone and your precious data against malware that can steal your information. 

Can malware attack WiFi?

Yes, malware can attack WiFi and distribute itself over the entire network quickly. This is especially true for public WiFi networks in malls, cafes, and airports, where many people access WiFi at the same time. 

Avoid connecting to public WiFi networks, and ensure you enable a reliable anti-virus program if you must connect to one.