What Is Malware and What Does It Do?

Malware is intrusive software that’s designed to disrupt computer programs. Some malware is designed to steal personal data, like banking information. Once it gets installed, it steals your credentials. Sometimes malware even poses as an antivirus program — cybercriminals attempt to change up malware tactics to trick users and exploit any security vulnerabilities.

Since computer hackers don’t give up easily, you should stay alert and use a top-rated antivirus product to prevent malware infections. Continue reading to learn more about why malware is dangerous and how to stop an infection from spreading to your device.

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What is malware?

Malware stands for “malicious software” and is software designed to harm or destroy computer systems and programs. The software is developed by cybercriminals who are known as hackers.

Hackers use malware attacks to steal data. Malware can sneak onto your computer and look for sensitive personal information, such as banking account details and credit card numbers. 

Cybercriminals can use this information to steal your identity, make purchases in your name, or steal money from your account.

Malware can also spread through computer networks where numerous devices are connected. When it does, it wreaks havoc by halting programs, stealing massive amounts of data, and sometimes holding systems hostage until a ransom is paid.

Malware can be a nuisance in some situations, but in many cases, it can be catastrophic, costing a ton of money and productivity. The best malware protection and antivirus programs work to prevent that from happening, but you should stay informed so you’ll recognize malware if it attempts to sneak into your computer.

10 different types of malware

You may already know there are computer viruses all over the internet, ready to deploy infections. The complex and sometimes confusing part is knowing there are several types of malware to look for and prevent.

The following list shows the most popular malware types and describes how they exploit your data.

1. Adware

Adware collects data about your browser usage and attempts to serve advertisements based on that usage. It may not always be dangerous, but it can be frustrating in any situation. 

You may get a ton of annoying pop-up ads while online, and your web browser may slow down to the point of being almost unusable. You could even get new extensions and toolbars added to your browser.

This malware can redirect your web browser to sites that may contain viruses. Also, when there is a significant amount of adware on your device, it can slow down your device and cause system performance issues. Most antivirus software protects against adware by constantly scanning for these programs.

2. Computer virus

A computer virus is a type of malware that can cause severe operational issues. These viruses are designed to spread through systems, files, and programs. They usually work by attaching to an executable host file that runs when the file is opened.

The code that contains the virus could spread from a document or software through means of file-sharing programs, external media devices, email attachments, and computer networks. When you have the best anti-malware software, it works with your specific operating system, like Windows, iOS, or Android, to help prevent computer viruses.

3. Cryptojacking

Cryptojacking is when cybercriminals use your computer without your knowledge to generate cryptocurrency like Bitcoin.

Cryptojacking works by installing a malicious program that gives hackers access to your device. The programs are called coin miners, and they’re used for creating cryptocurrencies. Coin miners may cause your device to run slowly because the program uses high levels of computer power.

4. Exploits

Exploits are codes that look for security or software vulnerabilities, like a way to get past your firewall. The malware gives a hacker backdoor access to your device or a network. Once they gain access, the hacker gets elevated privileges to target your data.

Some of these are known as zero-day exploits. That means the exploit finds a vulnerability that’s identified but not patched. The open vulnerability allows the intruder to access your device. Once in, they can drop in more malware. Updating antivirus software is important to fix any security vulnerabilities.

5. Keylogger

A keylogger is spyware that records everything you type on your keyboard and then sends the information to the hacker controlling the malware. A keylogger tracks every keystroke, including sensitive data such as passwords, email addresses, browser searches, and banking information.

A keylogger’s most prevalent symptom is a slow browser or lagging keystrokes and mouse movements. This software can often get installed by clicking on adware, which is another reason to keep your antivirus updated.

6. Ransomware

Ransomware attacks are particularly annoying and dangerous because they gain access to your sensitive information and encrypt it, so you can no longer access it. Then the hacker holds that information hostage until you agree to pay a ransom.

Many times, ransomware is part of a phishing attack or scam. You may click on a disguised link, thinking it’s from someone you know. Once the link gets clicked, the ransomware gets downloaded, and your data is stolen until the hacker receives payment to unlock it.

7. Rootkit

A rootkit program gives a hacker administrator-level access to your device. This malware conceals its presence and activities from you, allowing it to remotely execute files and even change system configurations on your machine without you noticing.

Once the rootkit infects the device, it can spy on your usage by accessing the computer's log files. It provides continued privileged access to your files without your knowledge that the malware is present.

8. Spyware

Spyware is malicious software that runs on your device in secret. It reports your sensitive information back to the hacker who controls it. Spyware may not immediately disrupt your applications because it wants to remain hidden. Eventually, it can grant a cybercriminal remote access and target your private data.

This form of malware can affect your device's speed and performance. It can also be the culprit behind identity theft, causing financial and legal issues through a data breach before the malware is sorted out.

9. Trojan horse

A Trojan horse gets downloaded onto your computer when it’s disguised as legitimate software. The malicious code is hidden in an attachment or email that is transferred to your device.

Once the Trojan horse gets installed, the code gives the attacker access to your files, online activity, and other data. This malware gets its name from Greek mythology. As the story goes, enemies of Troy got inside the gates by using a horse they pretended was a gift.

10. Worms

A computer worm is malicious software that spreads rapidly across a network to any device and doesn’t need a host program, unlike viruses. A worm gets downloaded or spreads through a network connection and then multiplies at an enormous rate.

Worms can cause data loss and severe operational disruptions. Since they self-replicate so quickly, they can consume large amounts of hard drive space and system memory. Worms can install other malicious programs, too, and give hackers access to your data.

TLDR: malware explained (video)

How do malware infections happen?

Malware infections happen to the best of us. It doesn’t always mean you haven’t been careful, but hackers are stealthy and can make malware look like legitimate software. With so much malware around, it can seem inevitable that you’ll be a target at some point.

The most common ways to get malware are through internet use and email. You could browse a legitimate site that’s been hacked and now shows malicious ads (sometimes called malvertising). You can also download infected files by opening a malicious email attachment. In worst-case scenarios, hackers hijack legitimate software (like in the case of CCleaner), and unsuspecting users download malware. 

There are some signs to look for to avoid malware. Be cautious when these present themselves, as they can be infections waiting to access your device.

• Email that looks similar to a legitimate source but is not exactly correct. It may even be misspelled. One of the best examples is accidentally typing Goggle.com instead of Google.com. The misspelled site then attempts to install malware that poses as security software.
• Malicious URLs that are hidden in linked text — hover over them to see the actual URL.
• Websites that ask you to sign in to access features or to post a comment. Make sure the login request isn’t a phishing attempt to get your username and password.
• Virus alerts claiming to be from large companies. Microsoft and other companies likely won’t contact you by phone or email to remove a virus. And if they do, hang up and call the number on the official site to make sure it’s a legit alert.
• Social engineering scams — hackers could pretend to be from your company’s IT department in an attempt to trick you into handing over sensitive data. 
  
• Transfer of malware from an infected computer — if your friend’s laptop has malware on it and they save some infected files to a USB drive, that malware could be transferred to your computer if you plug in the USB drive.
  

How do you know if you have malware?

You may know you have malware by recognizing common symptoms. There are some typical indicators that you have malware. For a more in-depth guide, you can read our article on how to detect malware on your computer.

Some of the usual suspects are:

• Your device is suddenly slow.
• You have tons of pop-up ads appearing while using the internet.
• Your device crashes or freezes frequently.
• Sudden loss of disk space is making it impossible to save new files.
• You get locked out of your files or the entire device.

How do I get rid of malware?

Now that you know the signs of malware, what do you do if you think you have malicious software on your computer? Fortunately, there are apps to help you remove malware from your device.

The most important asset you can use is good antivirus software. Antivirus and anti-malware programs help block malicious sites looking to access your machine. You also want to keep your software, operating system, and browser up to date. Often, the latest versions contain patches that fix new viruses. You should delete any malware your antivirus software finds.

Bottom line

Malware is any malicious software that attempts to invade your device. Malware is the umbrella term that describes any harmful code or program that disrupts a device’s system or operations.

The motives behind malware can vary, but none are good. It could be used to sabotage your work, costing you time and productivity. In other cases, it’s designed to steal, delete, or encrypt your data and hold it for ransom. Sometimes, malware is a tool to spy on your computer activity without your permission.

The good news is that with the help of a good antivirus or anti-malware tool, you’ll have much better protection from malware threats. It may also help you remove malware in case of infection.

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