What is Cybersecurity

Cybersecurity is the practice of protecting systems, networks, and data from digital attacks, unauthorised access, and damage. As organisations move more operations online, cybersecurity has become one of the most critical disciplines in information technology.

Why Cybersecurity Matters

Cyber threats are growing in frequency and sophistication:

2017 — WannaCry ransomware infects 230,000+ computers across 150 countries in a single day
2020 — SolarWinds supply-chain attack compromises thousands of organisations, including US government agencies
2021 — Colonial Pipeline ransomware attack disrupts fuel supply to the US East Coast
2023 — MOVEit Transfer vulnerability exposes data of 60+ million individuals globally
Today — the average cost of a data breach exceeds $4.5 million (IBM Cost of a Data Breach Report)

Cybersecurity is no longer just an IT concern — it is a business-critical function that protects revenue, reputation, and customer trust.

The CIA Triad

The CIA triad is the foundation of all cybersecurity:

Principle	Definition	Example
Confidentiality	Only authorised people can access data	Encryption, access controls, classification
Integrity	Data is accurate and has not been tampered with	Checksums, digital signatures, version control
Availability	Systems and data are accessible when needed	Redundancy, backups, disaster recovery

Every security control maps back to one or more of these three principles.

Beyond CIA — Additional Principles

Principle	Definition
Authentication	Verifying the identity of a user or system
Authorisation	Determining what an authenticated entity is allowed to do
Non-repudiation	Ensuring actions cannot be denied by the person who performed them
Accountability	Tracking and logging who did what and when

The Threat Landscape

Threat Actors

Actor	Motivation	Example
Script Kiddies	Curiosity, notoriety	Using pre-built tools to deface websites
Hacktivists	Political or social causes	Anonymous collective DDoS campaigns
Cybercriminals	Financial gain	Ransomware gangs (e.g., LockBit, ALPHV)
Nation-States	Espionage, sabotage	APT groups (e.g., APT28, Lazarus Group)
Insiders	Revenge, negligence, financial gain	Disgruntled employees leaking data

Attack Surfaces

The attack surface is the total number of points where an attacker can try to enter:

Network — open ports, exposed services, weak protocols
Application — web apps, APIs, mobile apps
Human — phishing, social engineering, credential theft
Physical — server rooms, USB devices, unattended laptops
Supply chain — third-party software, hardware components

Cybersecurity Domains

Cybersecurity is a broad field with multiple specialisations:

Domain	Focus
Network Security	Protecting networks from intrusion and attack
Application Security	Securing software from vulnerabilities
Cloud Security	Protecting cloud environments and data
Identity & Access Management	Managing who can access what
Security Operations	Monitoring, detecting, and responding to threats
Incident Response	Handling security breaches and incidents
Governance, Risk & Compliance	Policies, frameworks, and regulatory compliance
Cryptography	Protecting data through encryption
Digital Forensics	Investigating cyber incidents and preserving evidence
Penetration Testing	Simulating attacks to find vulnerabilities

Key Frameworks and Standards

Framework	Organisation	Purpose
NIST Cybersecurity Framework	NIST (US)	Risk-based approach: Identify, Protect, Detect, Respond, Recover
ISO 27001	ISO/IEC	International standard for information security management systems
CIS Controls	Center for Internet Security	Prioritised set of actions to defend against common attacks
MITRE ATT&CK	MITRE	Knowledge base of adversary tactics, techniques, and procedures
OWASP	OWASP Foundation	Application security best practices and the OWASP Top 10

The NIST Cybersecurity Framework

The five core functions:

Identify — understand your assets, risks, and vulnerabilities
Protect — implement safeguards (access controls, encryption, training)
Detect — monitor for security events and anomalies
Respond — contain and mitigate incidents
Recover — restore systems and learn from incidents

Career Paths in Cybersecurity

Role	Responsibility
Security Analyst	Monitor alerts, investigate incidents, triage threats
Penetration Tester	Simulate attacks to find vulnerabilities
Security Engineer	Design and build secure systems and infrastructure
Security Architect	Define security strategy and architecture
Incident Responder	Lead investigation and containment of breaches
CISO	Chief Information Security Officer — strategic leadership
GRC Analyst	Governance, risk, and compliance management
Threat Intelligence Analyst	Research and analyse emerging threats

Key Certifications

Certification	Provider	Level
CompTIA Security+	CompTIA	Entry
CEH (Certified Ethical Hacker)	EC-Council	Intermediate
CISSP	(ISC)^2	Advanced
OSCP	OffSec	Advanced (practical)
CISM	ISACA	Management

Tip: Cybersecurity is a mindset, not just a set of tools. Think like an attacker to defend like a professional.

Summary

Cybersecurity protects systems, networks, and data by applying the principles of confidentiality, integrity, and availability. The threat landscape includes nation-states, cybercriminals, hacktivists, and insiders. Frameworks like NIST and ISO 27001 provide structured approaches to managing risk. In the following lessons, we will explore networking, threats, cryptography, and the security controls that form the foundation of modern cyber defence.