Cybersecurity Introduction

Cybersecurity means protecting computers, networks, programs and data from attacks, damage and people who should not have access.

Why Cybersecurity Matters

Almost everything is digital now: bank accounts, mobile wallets, school results, medical records and shop orders. When something is digital, someone may try to steal it or break it.

A few everyday examples:

• Ayesha gets an SMS saying her bank account is blocked, with a link to "verify" it
• Ali's shop computer shows a message: "Your files are locked, pay to get them back"
• A company's customer list with phone numbers is leaked online

Good security habits prevent most of these problems. You do not need to be an expert to stay safe.

The CIA Triad

Security experts describe their goals with three words, called the CIA triad (nothing to do with any agency):

Every security control protects one or more of these three.

Basic Security Words

• Asset: something valuable, like data, money or a device
• Threat: something that could cause harm, like a thief or a virus
• Vulnerability: a weakness, like an old unpatched app or a weak password
• Risk: the chance that a threat uses a vulnerability, and how bad the damage would be
• Control: a step that reduces risk, like a password, a lock or a backup

You can think of it like a house: the TV is the asset, a thief is the threat, an open window is the vulnerability, and a window lock is the control.

Security is Layers

No single control is perfect. Good security uses many layers, called defence in depth:

1. A strong password
2. Two-factor authentication
3. Software updates
4. Antivirus
5. Backups

If one layer fails, another one still protects you.

Checking Your System is Updated

Updates fix vulnerabilities. On Windows you can check installed updates from the command line (PowerShell):

Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 3

Source   Description      HotFixID   InstalledBy          InstalledOn
------   -----------      --------   -----------          -----------
PC-ALI   Security Update  KB5031356  NT AUTHORITY\SYSTEM  10/10/2026
PC-ALI   Update           KB5030841  NT AUTHORITY\SYSTEM  09/12/2026
PC-ALI   Security Update  KB5029244  NT AUTHORITY\SYSTEM  08/08/2026

On Ubuntu Linux, you update everything with:

sudo apt update && sudo apt upgrade -y

Thinking Like a Defender

A simple way to judge risk is: risk = likelihood x impact. This small Python example scores a few risks from 1 (low) to 5 (high):

risks = {
    "Weak Wi-Fi password": (4, 3),
    "No backup of shop records": (3, 5),
    "Old phone with no updates": (3, 4),
}
for name, (likelihood, impact) in risks.items():
    print(f"{name}: score {likelihood * impact}")

Weak Wi-Fi password: score 12
No backup of shop records: score 15
Old phone with no updates: score 12

Fix the highest scores first. Here, making backups is the most urgent task.

Exercise