Introduction to Cyber Security

Cyber security is one of the most important topics in modern computing. This lesson introduces the fundamental concepts you need for your GCSE Computer Science exam, covering what cyber security is, why it matters, and the key terminology you will encounter throughout this unit.

What Is Cyber Security?

Cyber security is the practice of protecting computer systems, networks, programs and data from unauthorised access, damage, theft or disruption. It covers the technologies, policies and procedures that organisations and individuals use to keep digital information safe.

Every organisation that uses computers — from schools to hospitals, banks to governments — must think carefully about cyber security. A successful cyber attack can lead to:

Financial loss — stolen money, ransom payments, regulatory fines
Data breaches — personal information such as names, addresses and passwords exposed
Reputational damage — customers and the public lose trust
Service disruption — websites go offline, systems stop working, operations grind to a halt

Exam Tip: When asked to explain why cyber security is important, always provide at least two distinct consequences. The mark scheme rewards breadth — mention financial loss and reputational damage, for example, rather than giving two versions of the same point.

The CIA Triad

The CIA triad is the foundation of cyber security. It describes three goals that every security system tries to achieve:

Principle	Meaning	Example
Confidentiality	Only authorised people can access the data	Encrypting patient records so only doctors and nurses can read them
Integrity	Data is accurate and has not been tampered with	Using checksums to verify that a downloaded file has not been altered
Availability	Systems and data are accessible when needed	Keeping a backup server running so that a website stays online during a hardware failure

A successful cyber attack typically compromises one or more of these principles:

A data breach breaks confidentiality
An attacker modifying records breaks integrity
A denial-of-service (DoS) attack breaks availability

Threats, Vulnerabilities and Risks

These three terms appear frequently in exam questions. Make sure you can define each one precisely.

Threat — anything that has the potential to cause harm to a system (e.g. a hacker, a virus, a natural disaster)
Vulnerability — a weakness in a system that a threat could exploit (e.g. unpatched software, a weak password, an unlocked server room)
Risk — the likelihood that a threat will exploit a vulnerability and the impact it would have

Risk = Threat x Vulnerability x Impact

A system with many vulnerabilities and high-value data faces a greater risk than a system with few vulnerabilities and no sensitive data.

Who Carries Out Cyber Attacks?

Understanding the different types of attacker — and their motivations — is a key part of the GCSE specification.

Attacker Type	Motivation	Example
Black-hat hackers	Personal gain, financial theft, causing disruption	Stealing credit card details from an online retailer
White-hat hackers	Improving security (authorised, ethical)	A company hiring a penetration tester to find weaknesses
Grey-hat hackers	Finding vulnerabilities without permission but without malicious intent	Reporting a bug to a company after accessing their system without authorisation
Hacktivists	Political or social protest	The Anonymous group targeting websites to protest censorship
Nation states	Espionage, sabotage, political advantage	The Stuxnet worm targeting Iranian nuclear facilities
Script kiddies	Curiosity, showing off	A teenager using downloaded tools to disrupt a gaming server
Insiders	Revenge, financial gain, carelessness	An employee copying customer data to a USB drive before leaving
Organised crime	Large-scale financial gain	Criminal gangs running ransomware-as-a-service operations

Internal vs External Threats

Feature	Internal Threat	External Threat
Who	Employees, contractors, volunteers	Hackers, criminal groups, nation states
Access	Already have some authorised access	Must gain access first
Detection	Harder — actions may appear legitimate	Easier — may trigger security alerts
Examples	Accidental data leak, deliberate sabotage	Phishing attack, brute-force login attempt

Internal threats are particularly dangerous because insiders already operate within the organisation's defences. A well-meaning employee who clicks a phishing link can cause just as much damage as a deliberate attacker.

Why Cyber Security Matters for GCSE

Cyber security features in every major GCSE Computer Science specification (AQA, OCR, Edexcel). You are expected to:

Identify different types of cyber threats
Explain how attacks work and why they succeed
Evaluate the effectiveness of different prevention methods
Discuss the legal and ethical implications of cyber security

The remaining lessons in this unit will cover each of these areas in detail, building on the foundations established here.

Key Terms Summary

Term	Definition
Cyber security	Protecting systems, networks and data from unauthorised access or damage
CIA triad	Confidentiality, Integrity, Availability — the three goals of security
Threat	Anything that could cause harm to a system
Vulnerability	A weakness that a threat could exploit
Risk	The likelihood and impact of a threat exploiting a vulnerability
Black-hat hacker	A malicious attacker who breaks into systems illegally
White-hat hacker	An ethical hacker who tests systems with permission
Hacktivist	An attacker motivated by political or social causes
Script kiddie	An unskilled person who uses existing tools to launch attacks
Insider threat	A threat from someone within the organisation