Malware is a major threat to computer systems worldwide. It refers to software designed to disrupt, damage, or gain unauthorized access to systems. Common examples of malware in computers are viruses, spyware, worms, rootkits, Trojan horses, and many more, which we look at below.
Examples of Malware
The following are the common examples of malware in computers:
1. Viruses
Viruses are one of the oldest forms of malware. They attach themselves to files or programs and spread when users unknowingly open or share infected files.
Viruses spread quickly and can corrupt files, slow down systems, or even delete important data. They often require human interaction to spread, like clicking on a file or opening an email attachment.
Example: The ILOVEYOU virus spread through email in 2000. They damaging millions of systems worldwide.
2. Worms
Worms operate differently from viruses. They do not need user interaction to spread. Instead, they move through networks and exploit vulnerabilities. Their primary use is to create network overloads.
Hackers use worms to crash entire networks by generating excessive traffic. Sometimes, they are designed to steal sensitive data or distribute spyware across multiple devices.
Example: The Morris Worm was one of the first worms. It caused significant disruptions in 1988.
3. Trojan Horses
A Trojan pretends to be a helpful program but hides malicious actions. It often creates backdoors for attackers to control systems remotely. This access allows them to steal files, monitor activity, or control the device for malicious purposes.
Unlike viruses and worms, Trojans do not replicate. They are also used to install ransomware, encrypting files until victims pay a ransom.
Example: The Emotet Trojan is a notorious banking Trojan used to steal financial information.
4. Ransomware
Ransomware locks users out of their systems or encrypts their data. It demands payment (a ransom) to restore access. This type of malware is particularly harmful to businesses and organizations.
One of its most common uses is extortion. Hackers often target organizations that cannot afford downtime, such as hospitals or banks.
Example: The WannaCry ransomware attack in 2017 targeted businesses globally. They encrypted files until ransoms were paid.
5. Spyware
Spyware silently collects information from users without their permission. It is often installed alongside other software or through phishing links.
Hackers use spyware to monitor user activity, such as browsing history or email communication. They also use it to steal sensitive information, including passwords and financial data.
Example: Keyloggers are a common type of spyware used to record everything typed on a keyboard.
6. Adware
Adware may seem harmless compared to other malware types, but can still cause problems. It displays unwanted ads on devices, often disrupting the user experience.
One of its primary uses is to generate revenue for its creators by forcing users to click on ads. Some adware also tracks browsing habits to create targeted advertisements.
Example: Pop-ups or toolbars installed unintentionally often come from adware.
7. Bots and Botnets
A bot is a device infected with malware that allows attackers to control it remotely. When multiple bots are grouped, they form a botnet. It is often used for large-scale attacks like spamming or overwhelming servers with traffic (DDoS attacks).
Example: The Mirai botnet caused a massive internet outage in 2016 by overwhelming servers.
8. Fileless Malware
This type of malware does not rely on traditional files to infect a system. Instead, it operates directly in the memory, making it difficult to detect using standard antivirus software.
Example: Dark Avenger was an early example of fileless malware.
9. Logic Bombs
A logic bomb stays hidden until specific conditions trigger it, such as a particular date, user action, or system event. Once activated, it can delete files, corrupt data, or crash systems.
Example: A programmer installed a logic bomb in a company’s software, causing recurring errors that only he could fix.
10. Rootkits
Rootkits are advanced malware designed to gain administrator-level control of a system. They often modify system settings and hide other malicious programs.
Hackers use rootkits to turn off antivirus programs, making it harder to detect other malware. They also allow attackers to change system settings or create backdoors for future access.
Example: Rootkits were famously used in the Sony DRM scandal, exposing users to risks.
