Cybersecurity Fundamentals
Overview
Covers the IBM Cybersecurity Fundamentals and Google Foundations of Cybersecurity certifications, core security concepts, threat models, cryptography, and network security.
Core Security Principles
CIA Triad
| Principle | Meaning |
|---|---|
| Confidentiality | Only authorised parties can access data |
| Integrity | Data has not been altered without authorisation |
| Availability | Systems and data are accessible when needed |
Authentication vs Authorisation
- Authentication (AuthN), who are you? (passwords, MFA, certificates)
- Authorisation (AuthZ), what can you do? (RBAC, ACLs, policies)
Threat Landscape
| Threat | Description |
|---|---|
| Phishing | Social engineering via deceptive email/link |
| Malware | Viruses, ransomware, trojans, spyware |
| SQL Injection | Malicious SQL in user inputs |
| XSS | Inject scripts into web pages viewed by others |
| MITM | Intercept communication between two parties |
| DDoS | Overwhelm a service with traffic |
| Zero-day | Exploit unknown to vendor, no patch available |
Cryptography
- Symmetric, same key for encrypt/decrypt (AES). Fast, used for data encryption.
- Asymmetric, public/private key pair (RSA, ECC). Used for key exchange, TLS, signatures.
- Hash, one-way function (SHA-256). Used for password storage, integrity verification.
- TLS/SSL, encrypts data in transit. Uses asymmetric handshake then symmetric session key.
Network Security
- Firewall, filters traffic by rules (stateful/stateless).
- IDS/IPS, detects/prevents intrusion based on signatures or anomalies.
- VPN, encrypted tunnel over public network.
- DMZ, buffer zone between public internet and internal network.
- Zero Trust, never trust, always verify. Authenticate every request.
OWASP Top 10 (Web)
- Broken Access Control
- Cryptographic Failures
- Injection (SQL, command)
- Insecure Design
- Security Misconfiguration
- Vulnerable Components
- Authentication Failures
- Software Integrity Failures
- Logging/Monitoring Failures
- Server-Side Request Forgery (SSRF)
Best Practices
- Use MFA everywhere.
- Patch systems and dependencies regularly.
- Principle of least privilege, grant minimum permissions.
- Encrypt data at rest and in transit.
- Log and monitor all access.
- Never store plain-text passwords, use bcrypt or Argon2.
Cheat Sheet
CIA: Confidentiality | Integrity | Availability
Crypto: AES (symmetric) | RSA (asymmetric) | SHA-256 (hash) | TLS (transport)
Threats: Phishing | SQLi | XSS | MITM | DDoS | Ransomware
Defence: Firewall | IDS/IPS | VPN | MFA | Least Privilege | Zero Trust