💻 Paper 1 · Topic 5: The Internet & Its Uses
5.3a Cyber Threats
Cambridge IGCSE Computer Science 0478 · ~14 min read · ⭐ Pro

Types of Cyber Threat

Cyber threats are attempts to cause harm to computer systems, networks, or data. The Cambridge 0478 specification requires knowledge of the following specific threats:

1. Malware

Malware (malicious software) is any software designed to harm or exploit systems. Types include:

TypeHow it works
VirusAttaches itself to a legitimate file; replicates when the file is run; spreads to other files
WormSelf-replicates and spreads across networks without user action; can slow down systems
TrojanAppears to be legitimate software but contains hidden malicious code; does not replicate
SpywareSecretly monitors user activity and collects data (keystrokes, passwords) without consent
AdwareDisplays unwanted advertisements; may redirect browser
RansomwareEncrypts victim's files; demands payment (ransom) for the decryption key

2. Phishing

Phishing is a social engineering attack where fraudulent emails or messages are sent that appear to be from a trusted source (a bank, government, or well-known company). The goal is to trick users into revealing sensitive information such as passwords or credit card details, or clicking malicious links.

  • Spear phishing — targeted phishing directed at a specific person or organisation

3. Pharming

Pharming redirects users to a fake website even when they type the correct URL. The attacker corrupts the DNS cache (DNS poisoning) so that the domain name resolves to a different IP address controlled by the attacker. The user believes they are on the real site, but their credentials are captured.

4. Brute Force Attack

A brute force attack is a method of cracking a password or encryption key by systematically trying every possible combination until the correct one is found. This can be automated with software. Longer, complex passwords make brute force attacks impractical.

5. Denial of Service (DoS) / Distributed DoS (DDoS) Attack

A Denial of Service (DoS) attack floods a server or network with excessive traffic, making it unavailable to legitimate users.

A Distributed Denial of Service (DDoS) attack does the same but uses many computers (often compromised, forming a botnet) simultaneously, making it much harder to block.

6. Man-in-the-Middle (MitM) Attack

The attacker secretly intercepts and potentially alters communication between two parties who believe they are communicating securely. For example, intercepting data on an unsecured Wi-Fi network.

7. SQL Injection

An attacker enters malicious SQL code into a web form or URL input field. If the website does not properly validate input, the SQL code is executed by the database, potentially allowing the attacker to: view, edit, or delete database records; bypass login authentication.

Social Engineering

Social engineering is the use of psychological manipulation to trick people into revealing confidential information or taking actions that compromise security. It exploits human trust rather than technical vulnerabilities. Examples include phishing, pretexting, baiting, and tailgating (following someone through a secure door).

Exam tip: Know the difference between each malware type. For pharming vs phishing — phishing tricks the user into clicking a link; pharming redirects them automatically even if they type the correct URL. DDoS = distributed (many computers); DoS = single source.
⚠️ Common Mistakes
  • Confusing viruses and worms: viruses need a user to run a file to spread; worms spread automatically across networks
  • Confusing phishing and pharming: phishing requires the user to click a link; pharming changes where the domain name points
  • Saying ransomware deletes files — it encrypts them (they still exist but are inaccessible without the key)
Video coming soon
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Worksheet — Cyber Threats

6 questions · 14 marks

Q1State the difference between a virus and a worm. [2]
✅ Mark scheme
A virus attaches itself to a file and requires a user to run the file to spread [1]; a worm is self-replicating and spreads automatically across networks without user interaction [1]
Q2Describe how a phishing attack works. [3]
✅ Mark scheme
A fraudulent email (or message) is sent that appears to come from a trusted source [1]; it contains a link to a fake website or requests sensitive information [1]; the user is tricked into entering credentials or personal data, which is then captured by the attacker [1]
Q3Explain what a DDoS attack is and how it differs from a DoS attack. [3]
✅ Mark scheme
Both attack types flood a server with excessive traffic to make it unavailable to legitimate users [1]; a DoS comes from a single computer/source [1]; a DDoS uses many computers simultaneously (often a botnet) making it much harder to block [1]
Q4Describe what ransomware does. [2]
✅ Mark scheme
Ransomware encrypts the victim's files, making them inaccessible [1]; the attacker then demands a payment (ransom) in return for the decryption key [1]
Q5Explain the difference between phishing and pharming. [2]
✅ Mark scheme
Phishing tricks the user into clicking a fraudulent link (requires user action) [1]; pharming corrupts the DNS cache so users are redirected to a fake site even when they type the correct URL correctly (no user action required) [1]
Q6What is an SQL injection attack? [2]
✅ Mark scheme
SQL injection is when an attacker enters malicious SQL code into a web form or input field [1]; if the website fails to validate input, the SQL is executed by the database, allowing the attacker to view, modify, or delete records [1]
Quiz — Cyber Threats
Q 1 of 8
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TermDefinition
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Mini Test — Cyber Threats

10 minutes · mixed marks

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