Module 07: Security & Protection

Security is not a feature; it is the foundation of modern operating systems. In this module, we move beyond basic user permissions to understand the deep architectural mechanisms that prevent code from destroying the system. We will explore how the hardware enforces isolation (Ring 0 vs Ring 3), how the OS manages access control (DAC vs MAC), and how cryptographic primitives build trust in a hostile environment.

1. 🗺️ Module Roadmap

  1. Protection Mechanisms
    • Understand the Hardware/Software Contract.
    • Deep dive into Protection Rings (User Mode vs Kernel Mode).
    • Learn about Sandboxing and the Principle of Least Privilege.
  2. Access Control Lists (ACLs)
    • Move beyond chmod 777.
    • Master POSIX ACLs for granular file permissions.
    • Compare Discretionary Access Control (DAC) vs Mandatory Access Control (MAC) (SELinux).
  3. Authentication
    • Stop storing plain-text passwords.
    • Learn the mechanics of Hashing, Salting, and Peppering.
    • Understand Work Factors (Argon2, Bcrypt) and why speed is the enemy.
  4. Malware and Viruses
    • Anatomy of a Buffer Overflow (Stack Smashing).
    • Understand how Viruses, Worms, and Ransomware operate.
    • Learn about NX Bits and ASLR (Address Space Layout Randomization).
  5. Cryptography Basics
    • Symmetric (AES) vs Asymmetric (RSA/ECC) encryption.
    • How Digital Signatures guarantee integrity and authenticity.
    • The role of PKI (Public Key Infrastructure).
  6. Module Review
    • Flashcards for active recall.
    • Cheat Sheet for quick reference.
    • Key Takeaways summary.

Module Chapters

Chapter 04

Malware and Viruses

How does malware actually get into a system? It usually exploits a vulnerability. The most famous vulnerability in computer science history is the Buffer Overflow....

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