Free through lesson 3

Access-Control Weaknesses

From the basics of access control and least privilege, through protecting credentials, Linux and Windows permissions, the thinking behind privilege escalation, to closing it in design and operations. In 30 lessons you learn how misconfigurations and permission gaps get targeted, and how to close them. Every example and exercise targets only the fictional "Sample Corp." and your own local lab.

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Curriculum

The 30 lessons are split into 6 chapters. Working through them in order is recommended, but you can also dip into just the parts you need. * Examples such as privilege escalation exist to understand how flaws work and how to close them. Only try them against a practice environment you set up yourself or the consented labs on the security track.

Chapter 1 — Access-Control Basics (lessons 1–5)

Access control is the mechanism that decides "who may do what to what." This chapter covers authentication vs. authorization, access-control models, least privilege, and the basics of finding flaws.

What Access Control Is

The mechanism that decides who may do what to what. Its difference from authentication, and this course's premise.

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Subject, Resource, Operation

Capture access control in three elements, and grasp the differences among models (DAC/RBAC, etc.).

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Least Privilege & Separation of Duties

The principle of granting only as much as needed, and splitting permissions so one person cannot complete an act alone.

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Permission-Design Failure Patterns

Over-granting, neglect and implicit trust—design gaps that recur.

Finding & Recording Flaws

Enumerate permissions, reconcile against the "intended state," and make reproducible findings.

Chapter 2 — Protecting Credentials (lessons 6–10)

The wall of permissions is easily crossed once credentials leak. This chapter covers where credentials live, secret management, the paths by which they leak, and MFA.

Where Credentials Live

The permission wall is crossed once credentials leak. Know where what lives.

Secret Management

Centrally manage keys scattered in plaintext via env vars or a vault, and rotate them.

The Paths by Which Credentials Leak

Reuse, phishing, plaintext transmission, history remnants—typical routes keys get out, from the defender's view.

Storing & Verifying Credentials

Recap storage thinking for apps and the OS, and re-confirm hashes and one-wayness.

MFA & Conditional Access

Multiple factors of knowledge, possession and biometrics, and the lift of conditional access that judges by context.

Chapter 3 — Linux Permissions (lessons 11–15)

Linux permissions are made of simple rules of user, group and permission bits. This chapter covers those rules, sudo and SUID, and common flaws and hardening.

Linux Permission Basics

Read/write/execute for user, group and others. How to read ls -l.

sudo & Delegating Privilege

A mechanism to elevate only for needed operations, and the danger of widening the config too far.

SUID/SGID & Special Bits

The mechanism of running as the owner at execution time, and why it is abused for escalation.

Common Linux Misconfigurations

Writable critical files, weak permissions, neglected keys—the starting points of escalation.

Linux Hardening & Verification

Lock down with least privilege, updates and audit logs, and run inspection periodically.

Chapter 4 — Windows Permissions (lessons 16–20)

Windows handles permissions with its own mechanisms of accounts, tokens and ACLs. This chapter covers the basics, and common flaws hidden in services and shares.

Windows Accounts & Permissions

Local vs. domain, admin vs. standard user, and strong default groups.

Access Tokens & UAC

The bundle of privileges made at logon, and the mechanism that normally suppresses admin rights.

Permissions of Services & Tasks

Why misconfigured high-privilege resident processes are the classic Windows escalation vector.

Shares & File Permissions (ACLs)

Shared folders and NTFS ACLs, the pitfall of inheritance, and inspecting exposure.

Common Windows Misconfigurations

Weak services, plaintext credentials, old settings—bundled as inspection items.

Chapter 5 — The Thinking Behind Privilege Escalation (lessons 21–25)

Privilege escalation happens from an accumulation of small flaws. This chapter understands conceptually why and how escalation happens, and turns it into detection and closing.

What Privilege Escalation Is

The move of spreading from low to high privilege. Why the defender should know that thinking.

The Thinking Behind Misconfiguration Escalation

Organize the types of flaw that become footholds, from the viewpoint of inspection and fixing.

Credential Reuse & Lateral Movement

Cut the chain where a once-gained credential works elsewhere, via separation and uniqueness.

Detecting Signs of Escalation

Close in advance by inspection, notice after the fact by logs. Prevention and detection as two wheels.

Closing Privilege Escalation

Bundle least privilege, separation, updates and detection to cut escalation paths by design.

Chapter 6 — Closing It in Design & Operations (lessons 26–30)

Beyond squashing individual flaws, you prevent recurrence by design. This chapter covers least-privilege design, separation, inventory and audit, and how to write findings.

Designing for Least Privilege

A design template that builds permissions up from roles and makes the default deny.

Network Separation & Segmentation

Stop flat networks; use boundaries to curb lateral movement and blast radius.

Permission Inventory & Audit

Periodically enumerate permissions, find the unneeded, neglected and excessive, and return them.

Recording Findings & Fixes

Line up flaw, impact (propagation to privilege) and fix, and hand off with priority.

Wrap-up and Next

Fold basics through escalation and design into a template, and connect to the Windows/AD course.

After the 30 lessons, head to the Windows & Active Directory course, which covers the permission mechanisms and weaknesses at the center of the corporate network. The defender's view can be deepened in the server-hardening course too. Membership unlocks every course.