Difficulty: Beginner | Prerequisites: Basic understanding of how the internet works (HTTP, networks, servers).
This lesson introduces the most common security threats you will encounter in computing, along with the primary tools used to defend against them. It sits within the broader context of how the internet works (Unit 10) and assumes you know the basics of HTTP, servers and networks. Understanding these risks is foundational to everything from web development to systems administration, and this vocabulary will reappear throughout any computing course or career.
Hackers use techniques like phishing, keylogging and malware to steal data or damage systems. Defences include antivirus software, firewalls and SSL/TLS encryption. Know the vocabulary cold, because exam questions tend to test definitions and the difference between threats and protections.
Phishing
A social-engineering technique that tricks a user into handing over personal information (usernames, passwords, social security numbers). Typically arrives as a fake email claiming to be a system update or account alert.
In simple terms, this means someone pretending to be your bank or your university so you type your password into a fake page.
Keylogging
A program that silently records every keystroke a user makes, capturing passwords and other confidential data.
Think of it as an invisible notebook sitting between your fingers and the screen, writing down everything you type.
Malware
Software designed to damage a computing system or take partial control over its operation. An umbrella term that covers viruses, spyware, ransomware and more.
In simple terms, this means any software that is there to hurt you or your computer, not help you.
Virus
A program that runs on a computer to do something the owner did not intend. Viruses often replicate and spread to other machines.
Think of it as a biological virus: it infects a host, reproduces and spreads, except the host is your computer.
Freeware
Software available to download for free online. Freeware often contains bundled malware, so it should not be installed unless you are certain of its contents.
In simple terms, "free" software is not always free of risk. If you did not pay for the product, you might be the product.
Rogue Access Point
A wireless access point that provides unauthorised access to a secure network. An attacker sets one up to look like a legitimate Wi-Fi network and intercepts traffic from anyone who connects.
Think of it as a fake Wi-Fi hotspot in a coffee shop that looks real but is run by someone stealing your data.
DDoS Attack (Distributed Denial of Service)
An attack in which a virus installed on thousands of computers activates simultaneously, flooding a target server with traffic until it becomes overwhelmed and stops responding.
In simple terms, imagine thousands of people trying to walk through one door at the same time. Nobody gets through.
Antivirus Software
Software that maintains lists of known viruses and scans a computer to detect and remove them.
Think of it as a security guard with a mugshot book, checking everyone who walks in.
Firewall
Software (often running on routers or servers) that filters network traffic, allowing or blocking it according to a set of security rules.
In simple terms, a firewall is the bouncer at the door, deciding which traffic is allowed in and which is turned away.
SSL/TLS (Secure Sockets Layer / Transport Layer Security)
An encryption layer on top of HTTP that uses public-key cryptography to establish a secure connection between a browser and a server. This is what puts the "S" in HTTPS.
Think of it as sealing your letter in a locked box before posting it, so only the intended recipient can open it.
Phishing targets the human, not the machine. The weakest link in security is usually the person who clicks the link.
Keylogging targets input. The attacker does not need to crack your password if they can simply watch you type it.
Malware and viruses target the system itself, damaging files, stealing data or hijacking resources.
Freeware is the delivery vehicle. It is not a threat in itself, but it is a common way malware reaches your machine.
Rogue access points target the network layer. You think you are on a trusted network, but the attacker controls the connection.
DDoS attacks target availability. The goal is not to steal data but to take a service offline by overwhelming it with traffic.
Antivirus software is reactive. It identifies and removes known threats by matching them against a database of signatures.
Firewalls are preventive. They filter traffic before it reaches your system, blocking anything that does not match the rules.
SSL/TLS protects data in transit. Even if someone intercepts your traffic, the encryption means they cannot read it.
Threats and defences often pair up. Antivirus catches malware and viruses. Firewalls block the traffic used in DDoS attacks and can prevent rogue connections. SSL/TLS makes phishing harder (though not impossible) by letting you verify you are talking to the real server. No single defence covers everything, which is why security works in layers.
Students often think "malware" and "virus" mean the same thing. They do not. A virus is one type of malware. Malware is the broader category.
Students assume a firewall stops all attacks. A firewall filters traffic, but it cannot prevent a user from clicking a phishing link or downloading infected freeware.
Students believe SSL/TLS makes a website safe. SSL/TLS encrypts the connection, but the site on the other end can still be malicious. A phishing site can have a padlock icon.
Students confuse a rogue access point with hacking into an existing network. A rogue access point is a separate, fake network the attacker creates, not a breach of the legitimate one.
⚠️ Be able to define every term precisely. Exam questions often give a scenario and ask you to name the threat or defence.
⚠️ Know which terms are threats and which are defences. A common question format: "Which of the following would protect against X?"
⚠️ Understand DDoS as a volume-based attack on availability, not a data-theft attack.
⚠️ SSL/TLS is specifically about encrypting data in transit using public-key cryptography. Know the mechanism, not just the name.
⚠️ Freeware is not inherently malware, but it is a common vector. The distinction matters on multiple-choice questions.
True or False: A virus is a type of malware.
True or False: A firewall encrypts your data.
Fill in the blank: A ______ attack floods a server with traffic from thousands of compromised machines.
True or False: SSL/TLS guarantees the website you are visiting is not malicious.
Fill in the blank: ______ is the technique of recording every keystroke a user makes.
Q: A user receives an email from what appears to be their bank, asking them to verify their account by clicking a link and entering their password. What type of attack is this?
A: Phishing. The email is designed to trick the user into voluntarily providing their credentials.
Q: What is the difference between malware and a virus?
A: Malware is the broad category of any software intended to damage or control a system. A virus is one specific type of malware, a program that runs on a computer to do something the owner did not intend.
Q: How does a DDoS attack differ from other types of cyberattacks?
A: A DDoS attack targets availability rather than data. It overwhelms a server with traffic from thousands of compromised machines, making the service unreachable. It does not steal information directly.
Q: A student connects to "Free_Campus_WiFi" at a coffee shop near campus. The network is not run by the university. What security risk does this represent?
A: A rogue access point. The attacker has set up a fake wireless network to intercept the student's traffic.
Q: Name two defences covered in this lesson and explain what each protects against.
A: Antivirus software scans for and removes known viruses and malware from a system. A firewall filters network traffic according to security rules, blocking unauthorised connections and helping to mitigate DDoS attacks. (SSL/TLS is also acceptable: it encrypts data in transit to prevent eavesdropping.)
Q: Why is freeware considered a security risk even though it is not malware itself?
A: Freeware is a common delivery mechanism for malware. Because users download it voluntarily, it bypasses many technical defences. The risk is in what may be bundled with the free software, not the concept of free software itself.
This material connects directly to networking fundamentals (how HTTP, servers and routers work), because most of these threats exploit the way data travels across networks. If you go on to study web development, SSL/TLS and firewalls will reappear in the context of deploying secure applications.
The concept of social engineering (phishing) ties into broader discussions about human factors in security, which comes up in ethics and professional responsibility units. DDoS attacks connect to distributed systems and how the internet's architecture can be turned against itself.
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Quick Self-Test Answers: 1. True 2. False (a firewall filters traffic; SSL/TLS encrypts) 3. DDoS 4. False (it encrypts the connection but does not verify the site's intentions) 5. Keylogging