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What is malware?

Here’s everything you need to know about what malware is and how to prevent it.

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Everything you need to know about what is a malware_alt
Malicious software equals malware definition_alt

Malware definition

The definition of malware comes from combining two words: malicious + software = malware. Malware is software designed to work against the interests of the owner of a system or device. Some types can find their own way into your device, while others need to be planted there.

What does malware do? Its effects vary in severity, from tracking relatively harmless data to holding your device at ransom or destroying it for fun.

Types of malware and malware attacks

You’ll find malware types of every sort below. There are countless varieties out there, so we’ll stick to some of the most widespread malware examples. Here are the top most common types of malware:

Adware is a type of malicious software that focuses on making money_alt


Adware is a relatively innocuous type of malicious software that focuses on making money rather than harming your computer. This aggressive advertising-supported software displays banner advertisements on websites and application windows.

Symptoms may vary, but the main one will be pop-up ads. They may show up on your desktop or in programs, websites, or apps that didn’t have them before.

Spyware is spying on the man using computer_alt


Spyware is made to (surprise!) spy on you. This malware hides in the background, monitoring your computer usage and internet browsing activity. It can harvest passwords, banking details, and emails and even perform keystroke logging or change security settings. All of the information it gathers is sent to a remote user. It can also download and install other malicious applications without your permission.

Virus infects computer and other devices_alt


Much like a biological virus, a computer virus will spread from host to host to infect as many devices as possible. Attached to files or programs, it can be spread through downloads, email, social media, or text messages.

However, a virus usually cannot infect a computer autonomously – it needs a user to run the program it is attached to. The harm caused by viruses ranges from minor annoyances like desktop wallpaper alterations to major system crashes or complete loss of data.

Worms extracting information_alt


In comparison to viruses, worms can seem quite innocent, as they do not cause any direct damage to a system. A worm’s entire purpose is to copy itself and spread across a local drive or network.

Worms can also be paired with “payloads” designed to damage a system or extract information, but they don’t have to. The first worm, Creeper, simply notified infected users of its presence.

Trojan malware infiltrates woman’s computer and causes damage_alt


Trojan malware infiltrates computers by hiding in innocent-looking programs, like the Trojan horse of the Greek legend. Once it’s in, it can create backdoors for hackers to get into your system and collect your data or even completely lock you out of your computer. For example, the Zeus trojan collects data like victims’ keystrokes and credentials. Emotet was notorious for stealing data from individuals and companies alike.

Ransomware is cyber threat that spreads quickly and causes costly damage_alt


Ransomware is one of the most serious cyber threats due to its ability to spread quickly and cause costly damage. Ransomware is designed to make a profit. Once the malware infects a machine through a system vulnerability, it encrypts all data, locking the user out. Then, it asks the victim to pay a ransom to decrypt the files.

Keylogger tracking its victim_alt


Keylogging is the process of tracking the keys a user types to discover their sensitive passwords or monitor private communications. Different types of keyloggers exist, including ones based on stalkerware or hardware. This can make them very hard to discover as well.

How malware spreads

Malware could infect your devices in several different ways. Here are a few of the most common ones:


The most popular method of spreading viruses is through email. Both simple spam and sophisticated phishing attacks still trick people into clicking on links or downloading attachments that contain malware.

Careless browsing

If you click on any pop-up or advert that you come across while browsing, chances are, you’ll eventually end up on a malicious website. It will download malware in the background, and just like that, you’ll have a keylogger or a trojan on your device.


Some malware spreads from one device to another through the internal network. For example, someone in the office forgot their cybersecurity training and clicked on a malicious link. So the next day, everyone’s computers are infected, and all their files are encrypted, with no access to their accounts.

Bundled software

Malware is known for piggybacking. So even when you download a trustworthy piece of software, you might end up with more than you asked for. You can install malware together with legitimate software without even noticing, and it could be anything from slightly annoying adware to spyware stealing your banking data.

Signs of malware

Changes in speed

Your device or browsers have slowed to a crawl

Performance issues

Your device frequently freezes or crashes

Apps acting weird

Programs on your computer open or close without warning

Suspicious apps

Files, add-ons, or apps on your device that you don’t recognize

Setting changes

Your security, browser, or app settings change without your consent

Unusual messages

Unusual emails or texts that were sent without your permission


Your device overheats, or its battery drains super fast

Suspicious charges

Your phone bill has increased without you knowing why

How to prevent malware?

Here’s how you prevent a malware attack:

Woman using ultimate antimalware security software_alt
Staying safe by being aware of malware threats_alt
Back up files for extra protection_alt
Research and read reviews to avoid possible malware threats_alt
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Protecting devices with strong passwords_alt
Using NordVPN to stay extra safe_alt

Protect your digital life with more cybersecurity apps

Enjoy the all-round security provided by our apps. Protect your internet traffic, passwords, and files.

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NordPass password manager

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Get alerted before damage is done. A built-in NordPass Premium feature will scan the web and inform you if your sensitive information has been exposed in a data breach.

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Easy-to-use encrypted cloud storage

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How does NordVPN help?

How NordVPN can help depends on the malware you’re up against.

Blocks dangerous websites

NordVPN’s built-in Threat Protection feature blocks access to malicious websites before they have a chance to trick you into infecting your device.

Deletes malicious files

Threat Protection scans the files you download and, if malware is detected, instantly deletes it.

Fends off pop-ups

Threat Protection blocks potentially malicious ads before you even get the chance to see them.

Secures traffic

The encryption a VPN provides will close off numerous avenues of infiltration for potential hackers and their malware (but not all of them).

Enjoy robust cybersecurity with NordVPN

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