📖 What is Insecure Direct Object Reference (IDOR)?
Insecure Direct Object Reference (IDOR) is a vulnerability where an application provides direct access to objects based on user-supplied input. This allows an attacker to bypass authorization and access files, database records, or other user accounts by simply changing a parameter value in the URL or request.
"Remember, IDOR is primarily a failure of authorization, not authentication. If you see a URL with 'userId=123', always try changing it to '124' to test for this."
📚 Certification: CompTIA PenTest+ (PT0-002)
🔑 What are the Key Concepts of Insecure Direct Object Reference (IDOR)?
- ▸ IDOR occurs when an application lacks proper server-side authorization checks, allowing users to access resources they are not permitted to view or modify.
- ▸ Attackers typically identify IDOR by manipulating predictable parameters, such as sequential integers in URLs or API requests, to access different object records.
- ▸ Horizontal privilege escalation happens when an attacker accesses data belonging to a user with the same privilege level, such as another standard customer.
- ▸ Vertical privilege escalation occurs when a low-privileged user manipulates a reference to access administrative functions or sensitive system-level data.
- ▸ Effective mitigation involves implementing strict server-side access control lists and using non-predictable, indirect object references like UUIDs instead of sequential IDs.
🎯 How does Insecure Direct Object Reference (IDOR) appear on the PT0-002 Exam?
You may be asked to analyze an HTTP request where a URL contains 'account_id=5001'. The correct answer involves testing for IDOR by incrementing the ID to see if other accounts are accessible.
A scenario might describe a user who is logged in but can access another user's private profile by changing a parameter in the API call. You must identify this as IDOR.
Expect questions where you must differentiate between a failure in authentication and a failure in authorization; if the user is logged in but accesses a resource they don't own, it is IDOR.
❓ Frequently Asked Questions
Is using UUIDs a complete fix for IDOR?
No. While UUIDs make it harder for attackers to guess object IDs, they are 'security through obscurity.' The only complete fix is implementing server-side authorization checks to verify the user's ownership of the resource.
How does IDOR differ from general Broken Access Control?
Broken Access Control is a broad category of vulnerabilities. IDOR is a specific subtype where the vulnerability is triggered by providing a direct reference to an internal object, such as a database key.