Security Fundamentals

Core security principles, CIA triad, defense in depth, and security frameworks.

Overview

Understanding security fundamentals is essential for protecting digital assets.

Key Concepts

• CIA Triad — Confidentiality, Integrity, Availability
• Defense in Depth — Multiple security layers
• Least Privilege — Minimum necessary access
• Zero Trust — Never trust, always verify
• Security Frameworks — NIST, ISO 27001, CIS

Core Principles

Confidentiality

• Information accessible only to authorized users
• Encryption, access controls, authentication
• Data classification and handling

Integrity

• Data remains accurate and unmodified
• Hashing, digital signatures, version control
• Change management and audit logs

Availability

• Systems accessible when needed
• Redundancy, backups, disaster recovery
• DDoS protection and capacity planning

Defense in Depth Layers

┌─────────────────────────────────────┐
│         Physical Security           │
├─────────────────────────────────────┤
│         Network Security            │
├─────────────────────────────────────┤
│         Host Security               │
├─────────────────────────────────────┤
│         Application Security        │
├─────────────────────────────────────┤
│         Data Security               │
└─────────────────────────────────────┘

Common Threats

Practice

Identify security risks in a sample application and propose mitigations.