Digital Cybersecurity Fundamentals

Security is never absolute — it's an ongoing exercise in risk management and economic trade-offs. A vulnerability is a broken lock, a threat is a burglar looking for open doors, and risk is the probability the two meet.

1. 1.1The CIA Triad: Confidentiality, Integrity, and Availability Watch free
2. 1.2Risk Assessment: Risk = Threat × Vulnerability × Impact Watch free
3. 1.3The Principle of Least Privilege (PoLP) Watch free
4. 1.4Defense in Depth: Layering controls so one failure isn't fatal Watch free
5. 1.5Threat Modeling methodologies (e.g., STRIDE) Watch free

The most rigorous chapter — the mathematical mechanisms that protect data at rest and in transit. Core model: Ciphertext C = E(K, P), decryption P = D(K, C). Kerckhoffs's principle: only the key must stay secret.

1. 2.1Symmetric Encryption: Single-key systems (AES) and block vs. stream ciphers
2. 2.2Asymmetric Encryption: Public/private key pairs (RSA, Elliptic Curve Cryptography)
3. 2.3Cryptographic Hashing: SHA-256, the avalanche effect, and salting passwords against rainbow tables
4. 2.4Digital Signatures and message integrity
5. 2.5Digital Certificates: X.509 and how Certificate Authorities (CAs) establish trust

Cryptography secures the data; IAM controls who gets to use the keys. Authentication is the bouncer checking your ID; authorization is the bartender checking your VIP wristband — two entirely different mechanisms.

1. 3.1The Three Factors of Authentication: Something you know, have, and are
2. 3.2Authentication vs. Authorization
3. 3.3Access Control Models: Role-Based (RBAC) and Attribute-Based (ABAC)
4. 3.4Modern IAM: Single Sign-On (SSO), OAuth 2.0, and SAML
5. 3.5Zero Trust Architecture: Never trust, always verify

Building on networking fundamentals, how to protect the perimeters and internal segments of a network.

1. 4.1Firewalls: Packet filtering, stateful inspection, and Next-Generation Firewalls (NGFW)
2. 4.2Intrusion Detection/Prevention: IDS vs. IPS, signature- vs. anomaly-based detection
3. 4.3Network Segmentation: Using VLANs and subnets to limit lateral movement
4. 4.4Secure Tunnels: How VPNs use IPsec and TLS over untrusted mediums

Most breaches don't break cryptography — they exploit insecure code. A SQL injection is a form where the attacker writes instructions instead of a name, and an unsanitized system blindly executes them.

1. 5.1The OWASP Top 10: The most critical web application security risks
2. 5.2Injection Attacks: SQL Injection (SQLi) and Command Injection
3. 5.3Cross-Site Scripting (XSS): Stored, Reflected, and DOM-based
4. 5.4Cross-Site Request Forgery (CSRF)
5. 5.5Memory Vulnerabilities: Buffer overflows (primarily in C/C++)
6. 5.6The Secure Software Development Life Cycle (SDLC)

What happens when prevention fails — how organizations detect, contain, and recover from an active breach.

1. 6.1The Threat Landscape: Ransomware, Trojans, rootkits, APTs, and botnets
2. 6.2Social Engineering: Phishing, spear-phishing, and pretexting
3. 6.3Security Information and Event Management (SIEM)
4. 6.4The Cyber Kill Chain and digital forensics basics
5. 6.5The Incident Response Plan: Preparation, Identification, Containment, Eradication, Recovery, and Lessons Learned