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What Is Malware?

Lukas Grigas
Cybersecurity Content Writer

What is malware?

“Malware” is short for “malicious software.” It is designed to cause damage to systems, networks, and devices or to steal data. Malware can be something as simple as adware that shows a large number of annoying ads. But it can also be a malicious piece of software that destroys your hard drive and infects every device on your network.

Many types of malware have been developed, and it’s incredibly easy to end up with one on your laptop, smartphone, or even IoT devices. For the most part, cybercrooks use malware for a variety of purposes, such as:

  • Stealing sensitive data.

  • Taking control of the entire network.

  • Spying on specific organizations or individuals.

  • Requesting a ransom.

Fortunately, you can take several steps to avoid malware. Today we’re exploring the ins and outs of malware.

Types of malware

The damage malware can do to a device or system depends on the malware that has infected it. Different kinds of malware are identified by how they spread, operate, and the type of damage they cause.

Trojan. Named after the famous Trojan horse, it acts in the same manner. A trojan will get into a system disguised as legitimate software and will then work as a gateway for other types of malware.

Worm. Worms are similar to trojans in that they are also used to create backdoors for other types of malware. But unlike trojans, computer worms may have different purposes, like making multiple copies of themselves and overwhelming the network or taking up the whole hard drive.

Spyware. As the name suggests, spyware is used for spying. Spyware is difficult to detect because it works silently in the background, collecting information about the user. It may include their browsing history, usernames, passwords, and credit card information that is later sent to the attacker.

Adware. Adware is annoying but not necessarily dangerous. It can be used to collect data about the user and sell it to the highest bidder. But its main purpose is to show users ads — lots of them. It may, for example, change the homepage on their browser, redirect them to random sites, show pop-ups, or install toolbars and plugins without their permission.

Ransomware. Attackers use this type of malware to lock all files on their target’s computer until they pay a ransom. Ransomware usually gets in through a phishing email. When you open the email and click the link, the ransomware downloads and installs on your device. The user usually doesn’t notice anything until it’s too late.

Botnet. When specific malware infects your device, it becomes a part of a robot network — a botnet. Hackers use botnets to perform large-scale cyberattacks, like sending out spam emails or targeting companies and institutions with DDoS attacks. Once a device is infected, it will try to pass the malware on to other devices on the network, thus making the network even larger. Tens or even hundreds of thousands of devices may comprise a single botnet.

Virus. Computer viruses are one of the most common types of malware. The main difference is that a virus is not a standalone program — it needs to attach itself to legitimate software to operate, much like a biological virus. The damage a virus does to a system or device varies. It can do anything from producing annoying pop-ups to destroying a hard drive or stealing the user’s data.

Cryptojacking. Cybercrooks can, unbeknownst to you, make you mine Bitcoin for them in numerous ways. Usually, once the malicious piece of software designed to mine crypto enters your systems, it uses large quantities of your CPU’s resources to mine. The mining software can run in the background of your OS or even as a simple JavaScript in your web browser.

Malvertising. While similar to adware, malvertising has a more nefarious end goal than its counterpart. Primarily, cybercriminals use malvertising to deliver malicious software to the unsuspecting user’s device. Usually, cybercrooks provide ad networks with legitimate ads to be shown on legitimate sites. However, behind the scenes, bad actors set up the ad in such a way that if clicked, the ad redirects the users to malicious sites or prompts an installation of malware.

Keylogger. Malware designed to record every keyboard stroke is known as a keylogger. Attackers use keyloggers to access valuable information such as passwords, usernames, and credit card numbers.

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How does malware spread?

Bad actors are more sophisticated than ever in how they approach malicious software distribution. Here are some of the most common ways that malware spreads:

  • Phishing campaigns remain one of the most popular ways to distribute malicious software. During a phishing attack, cybercrooks send out emails that mimic the messages of legitimate businesses and institutions, intending to trick an unsuspecting user into downloading a malicious attachment or clicking on a malicious link.

  • Peer-to-peer (P2P) sharing systems are infamous for being one of the most common ways malicious software can spread. Using the P2P method, hackers can introduce malware into the network disguised as something simple as music or an image file.

  • System vulnerabilities can and often are used to distribute malware. Cybercrooks put in the work to understand a variety of operating systems so that they can find that one hole they can then exploit to no end. If cybercriminals successfully find a vulnerability, they can use it to get malware onto your system without you ever knowing anything about it.

Which devices does malware affect?

Today, you’d be hard-pressed to find a device that cannot be affected by malware. Android devices, macOS, and iOS devices can be infected with malware just like a regular PC. In fact, IoT devices such as your smart TV can get malware.

Recently, malware designed to affect macOS devices, which goes by the name of CrescentCore, was found to have the ability to evade sophisticated security measures by actively disabling anti-malware software on the affected device.

Bad actors usually use SMS and email as vectors for spreading mobile malware built for Android and iOS devices.

How to tell if you have malware?

Malware is not universal for all devices and may work and look differently on an iPad, a PC, or an Android phone. But some symptoms are the same, so make sure to look out for them:

  1. Your browser is acting weird. If you see loads of pop-up ads whenever you go online, new toolbars and plugins appear on your browser, or you get redirected to random websites, it probably means your device is infected.

  2. There’s no space on your drive. You might start getting notifications about running out of storage space. This is something that might happen naturally as files and programs pile up. However, if you are sure your device has loads of free space left, you might want to check for worms. They are known for making multiple copies of themselves and clogging up your drive.

  3. Apps and programs go awry. Some software on your device might start automatically and won’t shut down. It could be a simple bug, but if updates and online research won’t help, it’s better to start taking serious action. Try deleting the faulty software and perform a malware scan to ensure your device is clean.

  4. The device is slow and overheats. This can also happen naturally, especially if you’ve had this particular device for a while. But if the change in performance is sudden and the device is heating up even when you’re not using it, it might be a sign that you have malware.

  5. You’re locked out of your device. While some of these signs might seem ambiguous, this one is easy to spot. If you can’t access any of your files, it’s probably because of ransomware, and the attacker will tell you about it. Here’s a detailed guide on what to do in case of a ransomware attack.

How to remove malware

In most cases, removing malware from your computer or mobile device is possible by following a few simple steps. However, some malware can be complicated to remove manually. In such a situation, the standard practice is to use anti-malware software to detect and terminate the malicious piece of software. Here are a few simple yet effective steps that you can take to remove malware once and for all.

  • Get a reputable anti-malware or antivirus tool.

    Acquire a reputable tool to detect malicious or otherwise suspicious applications on your computer or mobile device. Anti-malware and antivirus tools are designed for real-time security and detection after infection. When looking for a tool to battle malware, be sure to research the provider extensively before making a purchase. Remember that cybercrooks often spread their malware with the help of faux advertising techniques, and they often masquerade as a reliable anti-malware tool.

  • Run a full system scan and remove malware.

    Run a full system scan with the anti-malware tool of your choice to identify the infection. Once the malicious software is identified, you’ll be able to remove it once and for all.

  • Change your passwords.

    Once you’ve successfully terminated the malicious piece of software from your device, make sure to change passwords on your online accounts. Bad actors often use malware to get their hands on valuable, sensitive information such as passwords, usernames, and credit card details. So if your computer or phone recently had a malware infection, it is safe to assume that at least the passwords of your online accounts have been compromised. To make the process of changing passwords quick and as smooth as possible, we highly recommend using a password generator — a tool designed to generate strong and unique passwords on the spot. To further up your security game, we suggest enabling multi-factor authentication on all your accounts and getting a password manager to help you with all the modern-day password needs you might have.

How to avoid malware?

In a perfect world, malware wouldn’t exist. Unfortunately, we live in a world where malware is prevalent, so it is up to us to stay secure as we navigate the complex online world. Here are a few simple yet effective ways that you can follow to avoid getting your devices infected with malware.

  1. Keep your software up to date. This means installing all updates as soon as they’re available — not only for your OS but for your apps, programs, and even browser plugins. A dangerous vulnerability pops up occasionally, and updates are immediately released to patch it. Your only job is to click “Install” and not “Postpone.”

  2. Be smart about the software on your device. Delete apps you no longer use, and always double-check what you download and install. Never use unofficial sources. Always see if the developer is trustworthy. Maybe that particular app or program has a vulnerability that is still not fixed? In that case, you should look for alternatives.

  3. nstall security software. Antivirus, anti-malware, a firewall, a VPN — whatever you need to stay safe online. This tip is especially important if you have family members who use the same computer. You never know what flashy ad they might be tempted to click.

  4. Back everything up. Keep your files in the cloud or schedule regular backups. Make sure to save the activation keys to software you’ve bought so you can recover your accounts if something happens to your device.

  5. Stay safe online. Malware typically ends up on a device when you click on malicious links or download fake software. Therefore:

  • Always check a link in an email before clicking on it, even if it seems genuine.

  • When you visit a website, see if there’s an “https” in the URL and a padlock icon next to it.

  • Only use a secure connection — don’t connect to public open Wi-Fi.

  • Make sure your passwords are strong and uncrackable. They should be long, complex, and unique. These are difficult to remember, so use a password manager like NordPass to store them in a cloud safely. This step, combined with 2FA, will ensure that your online accounts stay safe even if your device is compromised.

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