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Malware is malicious software that cyber criminals send to your computer or network to collect information, steal money, disrupt your business, and hold your reputation hostage.

While malware can wreak havoc on your computer network and valuable data, its effect is preventable. With the right cybersecurity measures, disaster recovery plan, and antivirus software, it’s possible to avoid unfortunate consequences.

Knowing the most common types of malware can help you prevent malware attacks, educate your employees, and improve security. Let’s take a closer look at malware types you should prepare yourself for.

Computer Viruses

A computer virus is a common type of malware that infects your computer and causes damage to your data. The key goal of a computer virus is to disrupt the way your system functions and cause operational problems.

Similar to human viruses, this piece of malicious code can spread across your programs and systems. They usually live in an executable file, which brings the virus to your system when you execute it.

The common signs of a computer virus include:

  • The device crashes.
  • The account logs out.
  • Programs start executing without your action.
  • Unwanted pop-up windows appear.
  • Your computer starts working slower than usual.

Today computer viruses spread between your devices (computers, laptops, tablets, smartphones) via the internet. They can appear at your digital doorstep through an email or with legitimate-looking software.

The most distinguishable feature of a computer virus is the need to execute its code. If you don’t run the .exe file or run the software, the virus will remain dormant.


A computer worm is a malicious program that reproduces and spreads across a network connection. Unlike viruses, it doesn’t enter computer files but spreads itself through all connected devices within the network by replicating itself.

Worms are infectious programs that run in the background and affect functions of your network’s software and hardware. The uncontrolled replication of worms affects your network. It can slow some tasks down file stopping others altogether.

In some cases, a worm can cause your connected devices to malfunction. This leads to downtime and substantial financial losses.

Computer worms can spread through:

  • Email as malicious attachments
  • Malicious links to a web resource
  • Links through messengers
  • Peer-to-peer file-sharing networks
  • Network packets.

To determine whether your network has a worm, you must pay special attention to the space on your hard drive. Malicious worms take up space, slow down the network, and delete files. If you notice missing files, you need to check your devices for worms.


Ransomware is a highly dangerous malware that can disrupt the company’s operation and cost you a significant amount of money. This malicious program enters your computer or network and paralyzes its activities or steals data.

Next, it offers to decrypt your data and restore access in exchange for a ransom, which is usually a hefty sum of money. The largest ransomware scandal of the decade happened back in 2021 when hackers attacked the Colonial Pipeline and received a sizable ransom.

While effective, ransomware attacks are preventable. The program usually enters your network because its users aren’t properly educated. Employees open infected files, download dangerous email attachments, share passwords, and more.

If a ransomware attack happens, the best weapon against it is backup. If you have a high-quality segregated backup, you can ignore the hackers’ requests and restore all the information from backup servers. Any qualified cybersecurity company can create and maintain a robust backup.

More than 4,000 ransomware attacks occur every day. Hackers don’t differentiate between small and large businesses. They could launch such an attack simply to test the waters or to train themselves. That’s why a company should always be prepared to protect its sensitive data.


A trojan horse is malicious software that poses as a legitimate program. A user downloads this program onto a computer, thinking that it can provide specific benefits. Sometimes, a trojan makes its way into legitimate programs. So when you are downloading a legit app, you are getting malicious code with it.

A trojan malware can hide in an email attachment or a file that’s free for download. Once it arrives at your computer, the program begins wreaking havoc. It can:

  • Provide backdoor access for other malware
  • Steal user data
  • Monitor your activity and report back to the hacker
  • And much more.

The key to discovering a Trojan horse on your computer is monitoring its activity. The common signs are a change in settings, slower operation, and unusual activity.

If your computer acquires a Trojan, it can spread the malicious program to other devices connected to the network.


Adware is advertising software that brings unwanted ads to your computer while you are browsing a website or using an app. While, by itself, the adware can be harmless, it can open a backdoor for other malicious programs.

This type of software usually demonstrates unwanted advertisements through pop-ups on your screen. It arrives on your computer when you install a free app. Once you install the app, adware installs itself automatically, without your knowledge.

Once Adware gains access to your computer or device, it can carry out dangerous tasks. For example, it can analyze your activity, record your locations, monitor browsing behavior, and much more.

The program reports back to its owner. Accordingly, you are unwittingly sharing information, which you may want to keep private.

The key signs of adware are:

  • Pop-up ads in strange places
  • Suddenly changed web browser’s homepage
  • Web browser speed decreases
  • Website links send you to unexpected locations
  • New extensions appear on your browser

Adware usually targets individuals rather than businesses. It collects private data and shares it with unauthorized parties.


Spyware is a type of computer malware that, well, spies on you. It infects your computer or mobile devices and collects information about your behavior online, files you download, passwords you use, and other data. Then it sends the information back to its owner.

You can get spyware through several channels, including:

  • Phishing– when hackers ask you to perform a certain action (clicking a link, downloading software) and you unwittingly agree.
  • Spoofing – creating sites that lead you to think that they are legitimate and encourage sharing sensitive information.
  • Software bundle – you download spyware together with some type of free app.
  • Trojans – you get spyware through a trojan that disguises itself as legitimate software.

The goal of spyware is to collect sensitive data and use it for the owner’s purposes. Even the smallest bits of information that these programs collect can find buyers and bring revenue to cyber criminals.

The common signs of spyware on your computer include unusual system instability, strange browser behavior (unexpected extensions, changes to homepage), slow loading websites, and problems with logging into secure websites.


A rootkit is a hidden computer program that gives its owner access to the computer where it’s hiding. Rootkits can be in a form of Trojans, worms, and viruses.

When a rootkit appears on your computer, it allows the hacker to maintain remote control over your computer or device without you knowing about it. It can execute files remotely, change system configurations, access log files, and spy on your activities.

Rootkits can remain on your computer for years. Unless your cybersecurity measures are aimed at detecting malware, they can easily hide their existence for a long time.

How to Prevent a Malware Attack

While many types of malware exist, all of them are preventable. All you have to do is follow certain steps and educate all computer and network users.

  • Install antivirus software – antivirus and antispyware programs usually do an excellent job detecting and deleting malware. All you have to do is keep security software updated and run it regularly.
  • Secure authentication – if your files are protected by just one password, it’s not enough. You need to implement a multi-factor authentication system and work on the strength of each password. You also need to limit access to authorized users within the company.
  • Update your software – all programs have loopholes. That’s why developers work hard to eliminate them and provide updates. If you don’t patch loopholes with updates, you leave your computer vulnerable to malware.
  • Email security – all your emails should be scanned for spam. All attachments must be checked by antivirus software before downloading. Your employees should know about phishing emails and learn how to identify them.

The key to avoiding malware attacks is eliminating human error. All your employees need to know about the types of attacks and how to avoid them. They should never share passwords, download unknown attachments, use free software from unknown developers, and more.

Learn More About Malware

Malicious software can cause serious damage to any company. Regardless of the size of your business, a simple ransomware program could lead to ruin reputation, lawsuits, and even bankruptcy. Thankfully, preventing malware attacks is fairly easy. All you need to do is implement a robust cybersecurity plan.

With the right approach to security vulnerabilities, you don’t leave hackers an opportunity to place malware on your computer and use it to paralyze operations, spy on you, or steal data.