What is Malware?

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The term ‘malware’ covers software that has been created specifically to damage servers, computers and networks. Common types of malware include: Trojan horses, ransomware, viruses, computer worms and banking malware.

The word malware derives from a combination of the words ‘malicious’ and ‘software’. Most malware types can steal, delete or encrypt sensitive data, hijack computers, and spy on a user’s activity.

ESET’s guide to malware covers how to detect, prevent and remove malware from your computer or mobile device using antivirus software.


How can I tell if my PC is infected with malware?

Should you start noticing unusual behaviour on your device, it’s important to investigate to prevent damage from potential malware. Some of the most common signs you have a malware infection on your device include:

  • A slower-than-normal device
  • Detecting apps you didn't download
  • Crashing and freezing frequently
  • A change in browser settings
  • Being spammed with ads and pop-ups
  • Being unable to open files or finding they're corrupted
  • Being redirected to a website you didn't click on

What steps should I take to remove malware?

If you detect malware on your computer or mobile phone, don't panic. The first thing to do is download security software that you trust. Make sure you’re using legitimate software designed to work with your device's OS.

There are plenty of free tools available, but it's best to use an antivirus package as these provide a more in-depth insight into your security. ESET offers antivirus software for PC, macOS and mobile devices to ensure protection from malicious software attacks. Once you've downloaded your antivirus package, you'll need to run a system scan to remove any malware.

It's also important to change any passwords you have. Do this across all of your devices and not just on the infected computer system. You can never be certain what sensitive personal data has been compromised, so it's best to protect everything.


What can malware do if it's not removed?

There are many reasons why a hacker might want to carry out malware attacks, from gathering sensitive information to damaging a network – meaning that should their use of malicious software be successful, it can often have a significant impact on your life.

You must ensure that any malware is adequately removed from an infected machine. Otherwise, you may experience issues with your security and devices. Malware could:

Slow down your devices
Malicious software uses up your device’s memory which, in turn, slows it down. Malware impacts the processing power of your device, causing your PC, Mac or mobile phone to become slow and unable to run.

Take sensitive personal data
Personal information is precious and malware attacks often target this when they infect a device. If you don't remove malware quickly, your sensitive personal information could be stolen, including passwords, login details, bank details and more.

Access personal files
Malicious programs can also affect your files and prevent you from accessing them. Hackers may take, delete or encrypt these and then use them to extort you.

Spread to other devices
One of the most significant dangers of malicious software is the risk of spreading to other devices. Worms, in particular, can spread rapidly through your network, which is significantly damaging for bigger corporations.


What are the different types of malware?

There are several types of malware, each with its own characteristics. Different types of cyber threats are determined by how they work and how they spread through a device.

A Trojan horse hides as a regular file or program to trick users into downloading and installing it. Once installed, a cybercriminal can control the infected computer to download further malware and access sensitive information and data.

Criminals use this malware type to extort users, encrypt data and block the screen. Ransomware will then hold the user's computer at ransom in return for a payment.

Adware spams users with malicious ads as a way of generating money. Not only does adware allow annoying ads to pop up on your device, but it also provides a way in for other types of malware.

A computer virus is similar to a human virus, as it copies itself to spread to other computers. The malware infection modifies legitimate files before executing a code when the infected program is launched.

Cryptomining malware
Cryptomining malware takes control of your devices to carry out cryptojacking – the cybercriminal hijacks your browser and uses your computer or mobile device to mine cryptocurrency.

Computer worms
Computer worms are self-replicating and independently spread. They exploit any vulnerability in the operating system and delete files, steal data or create botnets.

Scareware tricks and scares users into visiting malicious websites. Fake pop-ups appear on your device, warning you of a virus. These often tell you to download a fake security program to resolve the issue.

Banking malware
This malware type often hides as an app or program which is legitimate. Banking malware tricks users into installing it onto a device and then asks for banking details. Doing this allows cybercriminals to steal bank account access details and transfer money.

These are one of the most problematic types of malware to detect. Rootkits give hackers complete control over the device and can affect the software, operating system, hardware and firmware.

This type of malware spies on users and gathers their personal data. Spyware sits quietly in the background and steals financial information, passwords and GPS location data.

Keylogger malware hides similarly to spyware and collects information about your keystrokes. Hackers can gain access to personal data, including login information, credit card details and passwords.


How does malware spread?

There are several ways malware can spread, from infected personal computers and outdated software to malicious links or a malicious website. Keep up to date with the latest malware trends and know how your device could become infected with malware.

Infected ads and pop-ups
Ads and pop-ups are often used to carry and spread malware. You could even find these malicious ads on popular websites. Clicking on them downloads unwanted malicious software onto your device.

Another approach is via scareware. Pop-ups mimic security alerts and scare you into clicking a link or downloading infected software.

Emails and messaging apps
An email is a common way for malware to gain access. You may click on an infected link or attachment and unknowingly install the malware onto your computer. Once computer systems are infected, hackers can use your account to send emails to more people.

Unfortunately, phones can't escape malware either. By hijacking your messaging apps, hackers can send malicious links and attachments to your contacts, spreading infections further.

Drive-by downloads
You may never know that you've downloaded something malicious with this malware type. Hackers use DNS hijacking to redirect you to a malicious site, whether you clicked on it or not. Once you land on this redirected site, your computer will start to download infected files automatically.

USB flash drives
Another way to spread malware is through physical devices or media. USB flash drives are still a popular way of infecting devices. All it takes is for a computer user to plug in a USB drive and the malware can be transferred.


Why do cybercriminals use malware?

Early computer viruses were often used as a prank, but today they cause damage to users worldwide. Cybercriminals use malware for many reasons, including gaining money, gathering personal data, or damaging a network. Malware attacks can be created by anyone, from hackers and scammers to crime organisations and sometimes governments.

Malware authors generate money from their actions using different techniques. Some will use data to extort victims, and others will steal sensitive data and sell it. Other larger cybercriminal groups target others using more sophisticated and organised attacks.


Does malware affect Macs?

Yes, malware can infect Macs and mobile devices. With more people using Macs, malware infections have adapted to target these systems. Ransomware for macOS was first seen in 2016.

Other attacks, including Trojans, keyloggers and adware, have also been used by criminals to target macOS devices. Make sure you know how to check for a virus on your Mac to keep you safe.


Does malware affect mobile devices?

Malware does affect phones and tablets, and mobile malware is on the rise. When a phone or tablet connects to the internet, it’s at risk of a malware attack. For example, cyber criminals use malicious apps, app stores and phishing websites to target Android devices.

Even though iOS is more resistant to malware, Apple devices like iPhones and iPads aren't entirely secure. It's best to invest in suitable antivirus software for your device.


How you can prevent malware infections

The best way to prevent malware infections is to download security software that you trust. Make sure you are using legitimate software designed to work with your device's OS.

At ESET, we provide antivirus software for PC, Mac and Android, keeping your devices safe. Use the free ESET online scanner to detect and remove any malware threats. It is quick and easy to use, and you don't need to install it.

There are also some other steps you can take to protect against and prevent malware attacks.

Update software
Make sure that any software, browsers and plugins are up to date to protect against any system vulnerabilities. This includes the operating system and any applications.

Don't click suspicious links, emails or ads
Avoid clicking on any ads, pop-ups, emails or messages that seem suspicious. It may seem tempting, especially when an email seems legitimate. However, malicious attachments can easily compromise your system.

Only visit sites you trust
Avoid any websites which seem malicious or untrustworthy. Websites should use SSL to protect you. Look for a small padlock to the left side of the domain URL.

Use two-factor authentication
Where possible, in addition to using strong passwords, set up two-factor verification for logins. It might also be worth using a password manager to protect your passwords further.

Back up your data
Backing up your data regularly and storing it on an offline hard drive is another way to protect yourself from malware. Backups allow users to replace any damaged, corrupted or encrypted data easily.


Choose ESET Antivirus Software

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