Malware 101: Understanding the Threats Around Us

What is Malware?

Malware is harmful software designed to invade or corrupt your computer and/or network. It can steal, encrypt, or delete your data, alter or hijack core computer functions, and spy on your activity without your knowledge or permission. Malware can infect networks and devices, causing harm to those systems and their users in multiple ways.

Types of Malware

Virus

The most common type of malware. A virus attaches to a legitimate program and spreads when the infected program executes. It is a contagious piece of code that requires a host file and human intervention to activate. It can steal sensitive data, corrupt files, slow down performance, and crash systems. Notable example: ILOVEYOU (2000), which affected 45 million computers in just 10 days.

Worm

Unlike a virus, a worm can self-replicate without a host program and spreads across devices within a network without any user interaction. It consumes bandwidth, overloads infected systems, and can change or delete files, or introduce additional malware. Notable example: Stuxnet (2010), which targeted Iran's uranium enrichment centrifuges.

Trojan

A Trojan disguises itself as legitimate software to gain access to a system. It claims to perform one function while actually doing another. Once activated, it executes malicious functions — creating backdoors, stealing data, or installing additional malware. Notable example: FakeAV, a remote access Trojan (RAT) that secretly creates a backdoor into infected systems.

Spyware

Spyware collects information about the device and user — including keystrokes, browsing habits, location data, and login credentials — without their knowledge. It operates silently and transmits collected data to a remote server. Notable example: Look2Me, which tracks user behaviour and shares it with remote servers.

Ransomware

Ransomware infects a user's system, encrypts its data, and demands a ransom payment in exchange for the decryption key. It denies users and organisations access to their own files, causing financial loss, data loss, and reputational damage. Notable example: CryptoLocker.

Rootkit

Once installed, a rootkit gives attackers root or privileged access to the system. It hides itself in the operating system and modifies OS operations. Two types exist: KM Rootkits (kernel-mode, modifying kernel structures in memory) and UM Rootkits (user-mode, using user-mode APIs to manipulate the OS).

Adware

Adware tracks a user's browser and download history to display pop-up or banner advertisements. It uses location, search history, and browsing habits to serve targeted ads. Notable example: Gator (also known as Claria), notorious for pop-up ads and deceptive bundled installation.

Cryptojacking

Cryptojacking involves unauthorised use of someone's computer to mine cryptocurrency. The malware uses the victim's processing power without their knowledge or consent. Notable example: XMRig, an open-source cryptojacking tool commonly used to mine Monero or Bitcoin.

How Malware is Distributed

One of the most common distribution methods is phishing — emails disguised to look like they come from a trusted company or a known contact. Other vectors include malicious attachments, compromised websites, infected USB drives, and software bundled with unwanted programs.

How to Prevent Malware

Malware security protection provides an essential layer of defence for your computer or network:

1. 1Keep your system up to date with all OS and browser updates.
2. 2Avoid suspicious links and websites.
3. 3Be careful when opening email attachments or images.
4. 4Perform regular system backups.
5. 5Do not trust pop-up windows asking you to download software.
6. 6Use email filters to block malicious content before it reaches your inbox.