What is an insecure direct object reference (IDOR) vulnerability?
An IDOR vulnerability is a case where an attacker can access items such as files, databases, or other resources directly, bypassing the security and authentication measures. This vulnerability occurs when an application does not properly validate access to objects based on user inputs.
4 types of IDOR attacks
IDOR exploits many web components, so there can be a lot of very different IDOR attacks. But here are the main ones:
URL spoofing. In URL parameter manipulation attackers modify parameters in a web link to trick the system and gain unauthorized access. This can include manipulating numeric or text object identifiers, embedding special characters, and creating fake URLs to bypass security mechanisms.
Request body tampering. In this method, attackers modify the data passed in the body of an HTTP request to bypass security mechanisms. This includes modifying form parameters, JSON data, or other elements of the request body to achieve unauthorized access to resources.
Imagine you are logged into a web application to view your monthly billing statement, accessible via a URL like https://example.com/billing?userid=123. By simply changing the userid parameter in the URL to 124, you discover that you can access another user's billing statement without any additional authentication or authorization checks. This direct access to other users' data through manipulation of the URL parameter is a classic example of an IDOR vulnerability.
Manipulation of cookies or JSON identifiers. Here attackers manipulate cookies or identifiers to trick the system into accessing protected resources. This involves changing values in client-side cookies or JSON identifiers sent between the client and server to bypass authentication and authorization mechanisms.
Direct database and file access. With this method, attackers can exploit an IDOR vulnerability and generate a request that allows direct database and file access, bypassing the privileges required to do so or exploiting the lack of proper privilege design. This may involve manipulating query parameters to bypass filtering mechanisms and gain access to sensitive information in the database.
IDOR vulnerability prevention
Despite the variety of IDOR attacks, a few proven practices complicate attackers' success and help your system be more secure on different levels.
Effective authentication, authorization, and privilege detection. First of all, the implementation of multi-level authentication and authorization is recommended. Authentication policies should be deeply thought out, assuming all possible scenarios and access rights should be strictly configured according to privilege minimization principles.
Input control and validation. Thoughtful design and implementation of input filters and whitelists to prevent manipulation of object identifiers. Validation of user input should include checking the data format, screening out special characters, and ensuring consistency with the intended data type.
Restrict access through authenticated sessions. Session-based mechanisms for access control should be utilized. Objects should be accessed only through active and authenticated user sessions. It is also important to apply session time limitation and generation of new session IDs after each authorization.
Using GUIDs or random identifiers. Implementing globally unique identifiers (GUIDs) or random strings as object identifiers. This makes it harder for attackers to predict or brute force the identifiers, enhancing system security.
Link protection and encryption. It is necessary to avoid direct links to objects, as well as to apply encryption algorithms for data in the URLs of objects, and to implement the provision of temporary and disposable tokens to strengthen security. Of course, this includes the use of secure protocols like HTTPS and proxy servers to protect data in transfer.
- In IDOR attacks, a variety of exploitation of web components leads to different methods of unauthorized access.
- These include manipulating URL parameters, forging HTTP request bodies, manipulating cookies or JSON identifiers, or seeking direct access to databases and files by bypassing filtering mechanisms.
- To counter various IDOR attacks, you must employ strong security practices, including multi-level authentication, careful design of authentication policies, and configuring access rights based on privilege minimization principles.
- Avoid direct links giving direct access to databases and files, enable authenticated sessions and random keys, and use reliable protocols and encryption methods.
- Also, take care of input filters and whitelisting to prevent manipulation of object identifiers, provide special character validation, and maintain consistency in data format.