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Missing Authorization Checks

Some vulnerabilities are technical.
Missing authorization is philosophical.
It’s not about broken code. It’s about missing questions.
Who is this user? What are they allowed to do?
If the system never asks, it cannot protect.

What this page covers

  • What missing authorization checks are: the concept, the mechanics, and the impact
  • How to exploit them: patterns, examples, and testing strategies
  • How to defend against them: role validation and access control models
  • How to detect them: signs, tools, and manual review
  • How I’ve practiced it: labs, notes, and logic abuse experiments

This isn’t just about access.
It’s about understanding how permission is granted, and how it can be forgotten.

What Missing Authorization Actually Is

Authorization is the process of verifying whether a user has permission to perform an action or access a resource.
When a system fails to check authorization, it allows users to do things they should not be allowed to do.
This is different from authentication, which only verifies identity.
Authorization is about what a user can do, not who they are.

The Core Idea:

The system trusts that if a user is logged in, they are allowed to do anything.
It never checks their role, ownership, or access level.

Common Examples

  • Any logged-in user can access admin-only endpoints
  • Users can delete or modify resources they do not own
  • Role-based features are hidden in the UI but not protected in the backend
  • APIs return data for other users without verifying ownership
  • Mobile apps allow privilege escalation through tampered requests

Missing authorization checks are often found in:

  • REST APIs
  • Admin panels
  • File management systems
  • Multi-tenant applications
  • Mobile and desktop clients

What Happens When It’s Exploited

  • Unauthorized access to sensitive data
  • Account takeover through logic abuse
  • Data tampering or deletion
  • Privilege escalation
  • Full compromise of business workflows

This vulnerability doesn’t need clever payloads.
It just needs a system that never asks the right question.

How to Mitigate Missing Authorization

1. Enforce Role-Based Access Control (RBAC)

Define clear roles and permissions.
Check them on every sensitive action.

2. Validate Ownership

For user-specific resources, confirm that the requester owns the object.
Never trust client-side indicators.

3. Protect Endpoints, Not Just Interfaces

Do not rely on hiding buttons or links.
Secure the backend logic with proper checks.

4. Use Centralized Authorization Logic

Avoid scattered permission checks.
Use middleware, decorators, or access control libraries.

5. Test for Vertical and Horizontal Privilege Escalation

Try accessing resources as different roles and users.
Automate where possible, but always test manually.

Mitigation is about asking the right questions.
Not just “is this user logged in,” but “should they be allowed to do this?”

How I Practice Authorization Testing

I explore:

  • APIs with predictable endpoints
  • Admin features exposed via direct access
  • Multi-user systems with shared resources
  • Mobile apps with tamperable requests

I test:

  • Role escalation by modifying tokens or parameters
  • Ownership bypass by changing IDs
  • Hidden features by guessing URLs
  • Logic flaws that skip permission checks

Every time I find a missing check, I learn something about how systems assume trust — and how dangerous that assumption can be.

Final Thought

Missing authorization is quiet.
It doesn’t throw errors or crash servers.
It just lets you walk through doors that were never locked.

This page is my study of those doors.
Not just how to find them, but how to close them, and explain why they matter.