Malware, i.e., “malicious software,” is software that has been created to harm computers. Malware is an umbrella term that includes many different types of threats. Specific examples of these types and how they attack computers are:
Ransomware
Ransomware encrypts files or computers making them inaccessible until the owner pays a ransom. The number of ransomware attacks and ransom amounts increased in 2024 over previous years. One of the most common ways for a computer to become infected with ransomware is by opening documents attached to phishing e-mail. Other infection methods are social engineering attacks, using outdated software, using pirated software and visiting malicious websites.
Viruses
Viruses are programs that infect computers by attaching themselves to files on the targeted computer. Once a computer has been infected, the virus will attempt to replicate itself on additional computers that can be reached from the victim’s device. The potential damage that a virus can do includes slowing down the computer, causing the computer to crash, displaying unusual error messages or screens, damaging or deleting critical files and stealing data like credit card numbers, usernames, passwords and browsing history.
Worms
Worms are similar to viruses but do not need human action to get installed on a computer. Viruses need users to do something like click a link or open an infected email attachment. Worms, in contrast, can spread by exploiting vulnerabilities in computer operating systems.
Bots
Bots are computers that are infected with malware that allows a cybercriminal to control them remotely without the owner’s knowledge or permission. Many kinds of electronic devices can be turned into bots. For example, desktop computers, laptops, tablets, smartphones, wireless cameras, routers, smart thermostats and smart speakers are all vulnerable. When a bad actor controls multiple bots, it’s called a botnet or bot army. Some botnets contain hundreds of thousands of devices. Bots can be used to send out spam, crack passwords, participate in credential stuffing attacks, post items on social media sites, collect email addresses, engage in click fraud or participate in DDOS (Distributed Denial of Service) attacks to cripple websites.
Keylogging
Keylogging malware records keyboard activity of the victim computer. Periodically this data is sent back to the cybercriminal who created the keylogger. By observing all activity on a device, the criminal can learn the owner’s account IDs and passwords used for logging into applications and websites. The criminal could then log into an account and withdraw all of its contents.
Scareware
Scareware is malware that displays a warning on a monitor stating that the computer is infected with a virus. It’s actually just a harmless pop-up ad like many others that people see all the time. Scareware tells the user that by clicking a button or link the threat can be removed. If the user clicks on it then a virus, ransomware or other form of malware will be installed. Users can prevent pop-up ads, including scareware, from being displayed by installing a pop-up blocker in their browser.
Spyware
Spyware is software that literally spies on computers and smartphones it is installed on. It collects personal data like credit card details, usernames, passwords, banking information, geographic location data, calling history and browsing history. Once collected, this data is sent to the cybercriminal behind the spyware. If the bad actor can obtain usernames and passwords, he will be able to log into and take over the victims’ accounts.
Cryptojacking
Cryptojacking is a form of malware that uses the victim’s device to mine, i.e. create cryptocurrency. Mining cryptocurrency takes an enormous amount of computing power and electricity. If cryptojacking software is installed on your computer, you’ll end up with a much slower computer and higher electricity bills while any cryptocurrency profits will go to the criminal.
Adware
Adware displays unwanted ads on computers or smartphones where it’s installed. Victims experience a slower computer as well as the frustration of having to close ads that keep appearing on the screen. The bad actor that created the adware receives a small payment for every ad that’s shown to the victims. Adware can infect a computer if the user downloads free applications, games, videos or music that have had this malware included in them.
A Trojan horse
A Trojan horse is malware disguised as an application, game or other piece of useful software. The victim installs it thinking he’s getting something for free. Once it’s installed it can have many of the negative actions that other malware causes without the victim knowing about it.
Common ways for devices to be infected with malware are:
Opening e-mail attachments that contain a virus or other malware.
Clicking on links in e-mail that take you to a malicious website.
Downloading software, games, video, etc., from an unsafe site.
Plugging an infected USB drive into your computer.
Visiting an infected website. This is called a “drive-by download.”
Clicking a link in a text message leading to a malicious website and causing an infection.
Signs that a device has been infected with malware include:
Performance degrades.
The computer freezes or crashes more frequently than normal.
Unexpected new programs, toolbars or icons.
Programs you didn’t start are running.
If a computer is infected with malware the owner should purchase, install and run a reputable antimalware program to remove it. In an extreme case, all the computer’s software would need to be deleted and reinstalled. Your data would then be restored from backup files you’ve previously created.
The following actions are ways that users can prevent malware infections on their computer and phones:
Install an antivirus or antimalware package and keep it updated.
Apply all updates and patches to the operating system, browsers and other applications on your devices.
Install a pop-up blocker in your internet browser.
Exercise caution before clicking on questionable links or buttons.
Download software only from reputable websites. For iPhones it’s the App Store. For Android phones it’s the Google Play Store.
Avoid suspicious websites.
Create regular backups. This won’t prevent malware infections but can help restore your computer to its previous state after the malware has been removed.
Malware is a very real danger for computers and other electronic devices, but it can be avoided. By following the actions in the previous paragraph, users can help prevent malware from impacting their lives.
