Introduction to Cybersecurity
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What is Cybersecurity?
Cybersecurity is the discipline of protecting computers, servers, mobile devices, networks and data through a combination of technology, processes and people.
The Three Pillars — People, Process, Technology
Cybersecurity is not just a set of tools. It stands on three interconnected pillars — and the weakest one decides the strength of the whole.
Cyberspace is the borderless virtual world of computers, cables and satellites. Information Security protects all information — even locked filing cabinets. Cybersecurity is the digital branch of Info Security — protecting devices, networks and cloud within cyberspace.
The CIA Triad — Cybersecurity's Foundation
Confidentiality — only authorised people see the data. Integrity — the data hasn't been silently changed. Availability — the system is up when it's needed. Break any one, and security has failed.
CIA in Practice — Examples & Failures
Example: your bank balance only you can see.
Break it → data leaks, identity theft.
Example: salary in payroll matches your contract.
Break it → falsified records, wrong balances.
Example: hospital systems working during emergencies.
Break it → outages, business stops.
Modern frameworks add Authentication (who are you?), Authorization (what may you do?), and Non-repudiation (you can't later deny you did it).
How an Attack Reaches You
A threat starts with the attacker, rides across the internet, hits your firewall (which filters known-bad traffic), and — if it slips through — reaches your device. Every hop is an opportunity to detect and block.
The Ten Threats You Must Know
The Terminology You'll Hear Every Day
| Term | What it means | Example |
|---|---|---|
| Asset | Something valuable that needs protecting | Customer DB, laptop, source code |
| Threat | A potential danger | A hacker planning to steal files |
| Vulnerability | A weakness that could be exploited | An unpatched Windows machine |
| Exploit | The actual code that abuses a vulnerability | A script that hits the unpatched machine |
| Risk | Probability that harm occurs | 90% chance of infection without a patch |
| Attack Vector | The route the attacker uses | Phishing email, infected USB |
| Payload | The malicious content inside | Ransomware embedded in a PDF |
| MFA / 2FA | Second factor beyond password | Password + SMS OTP |
| Incident vs Breach | Suspected event vs confirmed loss | 100 failed logins → 10M records leaked |
Risk = Threat × Vulnerability × Impact — reduce any factor, reduce the risk.
Defence in Depth = Layer 1 + Layer 2 + Layer 3 — no single control catches everything.
Defence in Depth — The Layered Model
The attacker has to defeat every ring to reach the data. Physical (locked server rooms) → Network (firewalls, IDS) → Application (auth, input validation). Each layer buys defenders time to detect and respond.
Modern Challenges — Part 1
Modern Challenges — Part 2
Defenders must protect every door, every hour, every day. An attacker needs to find one open door, once.
Case Study — The WannaCry Hospital Attack
The killer detail? Microsoft had shipped the protective patch two months earlier. Infected hospitals simply hadn't installed it.
Total damage worldwide: over $4 billion.
Confidentiality gone — attackers accessed records. Integrity gone — files encrypted, unreadable. Availability gone — systems offline for days. One missed update collapsed the entire triad.
The Eight Golden Rules — 1 to 4
The Eight Golden Rules — 5 to 8
Cybersecurity Starts With Fundamentals
Everything else in cybersecurity — penetration testing, incident response, cryptography, cloud security — builds on what you just learned. The CIA triad, the threat vocabulary and the golden rules are the language of the entire field.
Study each threat type in depth. Practise on TryHackMe and HackTheBox. Watch the Verizon DBIR annually. Consider certifications like CompTIA Security+ or (ISC)² CC to formalise your knowledge.
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