Summary:

This bug bounty report highlights a critical URN (Uniform Resource Name) Injection vulnerability . Exploiting this vulnerability allows unauthorized access to sensitive resources and potentially results in data leakage. Immediate attention and mitigation measures are necessary to safeguard the system’s integrity and protect user information.

A URN (Uniform Resource Name), which makes use of the urn system, is a persistent identification for internet resources.

Every resource on the internet, regardless of its format, such as a website or email, is identified by a string of characters that doesn’t depend on its physical location.

URNs are given specified namespaces by a namespace authority, which ensures that they are distinct and enduring over time even if the resource to which they are associated changes or disappears.

For instance, the URN doesn’t change when resources and objects move, unlike a URL (Uniform Resource Locator), which loses validity when data is relocated to a new place.

Description:

Through extensive testing and analysis, I have discovered a URN Injection vulnerability within the target system. This vulnerability arises due to improper validation and sanitization of user-supplied URN parameters.

Attackers can exploit this vulnerability to manipulate URN values and potentially gain unauthorized access to sensitive resources or perform malicious actions.

Steps To Reproduce

1. Visit the login page of example.com.
2. Locate the “Username” input field.
3. Inject a malicious URN value into the “Username” field, bypassing any input validation or sanitization. Example:

urn:example:user; SELECT * FROM users WHERE username='admin' -

4. Enter any password in the corresponding “Password” field.

5. Submit the login form.

6. Observe the behavior of the application. If the URN Injection vulnerability exists, the system may process the injected URN value without proper validation.

7. Check for unauthorized access or unintended actions:
— If the application logs in successfully with the injected URN value, unauthorized access to a user’s account has been achieved.

Impact

• Attackers may gain access to restricted resources or perform actions that should be restricted to authenticated users only.
• Sensitive data or user information could be exposed, leading to privacy breaches and potential misuse.
• Attackers may abuse the system by injecting malicious URNs, which could lead to further compromise of the application, such as executing arbitrary code or injecting malware

Recommendations

• Implement strict input validation and sanitization mechanisms for all user-supplied URN parameters. This should include filtering or encoding special characters and validating the format and structure of URNs.
• Apply the principle of least privilege by ensuring that the access control mechanisms are properly implemented and restrict user access to only the necessary resources.