STUDY GUIDE · GKU 6
System security study guide (Cybersecurity)
This unit is about the machine under the network: the operating system that shares one processor, one memory and one set of devices among programs that do not trust each other. The first part explains what an operating system does and how it does it — process states and scheduling, context switches, synchronisation and deadlock, paging and virtual memory, files, inodes and permissions, device drivers, the kernel/user boundary, system calls, address-space randomisation, non-executable memory, sandboxing, and the isolation choices of monolithic kernels, microkernels and hypervisors. The second part is hardening: installing from a known baseline, removing services and ports that are not needed, configuring users, groups and sudo, hardening SSH and file permissions, patching on a tested cadence, scanning for vulnerabilities and reading the results honestly, and using virtual machines and golden images without mistaking a snapshot for a backup. The third part is security testing: reconnaissance and scanning, exploitation treated conceptually, post-exploitation described from the defender's side, the testing methods and methodologies in use, and the ethics, law and authorisation that separate a test from a crime. Every section opens with a quick-revision card, and the worked examples run from easy to exam level.
Structured by the official ETEC subject standard for this topic: every listed topic and learning outcome, with formulas, figures and worked examples. The full sections are available to members in the app.
SKU 6.1 · Concepts of operating systems
Operating systems: processes, memory, files and protection
What an operating system is for, how a process moves between states, how memory is translated and protected, how files and permissions work, how the kernel and user mode are separated, and how monolithic kernels, microkernels and hypervisors isolate failures.
SKU 6.2 · Operating system hardening
Secure installation, access control and patch management
Building a host from a known baseline: minimal services and ports, host firewall, users, groups and sudo, SSH and file permissions, patch cadence and testing, vulnerability scanning and CVSS, and virtualisation with snapshots and golden images.
SKU 6.3 · Security testing
Reconnaissance, scanning, exploitation and secure testing
How a test is planned and executed defensively: passive and active reconnaissance, port and service scanning, exploitation at the conceptual level, post-exploitation seen from the defender's side, the testing types and methodologies, and how findings are validated and reported.
Ethical, legal and validation practices
Authorisation, scope and rules of engagement, responsible disclosure, the Saudi Anti-Cybercrime Law and the PDPL, data handling, reporting, conflicts of interest, and what to do when a test finds something outside its scope.
MORE CYBERSECURITY GUIDES
- Cybersecurity foundations: principles, threats, risk and governance study guideGKU 1 · 3 sections
- Data security: cryptography, forensics and databases study guideGKU 2 · 6 sections
- Software security: development, secure coding, design and algorithms study guideGKU 3 · 5 sections
- Component security: architecture, vulnerabilities and environments study guideGKU 4 · 2 sections
- Network security study guideGKU 5 · 5 sections
- Human security: threat actors, techniques and awareness study guideGKU 7 · 2 sections
- Organisational security: ethics, law, risk and economics study guideGKU 8 · 3 sections