Testing for Bypassing Authorization Schema (OTG-AUTHZ-002)

OWASP Testing Guide v3 Table of Contents

This article is part of the OWASP Testing Guide v3. The entire OWASP Testing Guide v3 can be downloaded here.

OWASP at the moment is working at the OWASP Testing Guide v4: you can browse the Guide here

Brief Summary

This kind of test focuses on verifying how the authorization schema has been implemented for each role/privilege to get access to reserved functions/resources.

Description of the Issue

For every specific role the tester holds during the assessment, for every function and request that the application executes during the post-authentication phase, it is necessary to verify:

• Is it possible to access that resource even if the user is not authenticated?
• Is it possible to access that resource after the log-out?
• Is it possible to access functions and resources that should be accessible to a user that holds a different role/privilege?
• Try to access the application as an administrative user and track all the administrative functions. Is it possible to access administrative functions also if the tester is logged as a user with standard privileges?
• Is it possible to use these functionalities for a user with a different role and for whom that action should be denied?

Black Box testing and example

Testing for Admind functionalities
For example, suppose that the 'AddUser.jsp' function is part of the administrative menu of the application, and it is possible to access it by requesting the following URL:

• https://www.example.com/admin/addUser.jsp

Then, the following HTTP request is generated when calling the AddUser function:

POST /admin/addUser.jsp HTTP/1.1
Host: www.example.com
[other HTTP headers]

userID=fakeuser&role=3&group=grp001

What happens if a not administrative user tries to execute that request? Will the user be created? If so, can the new user use her privileges?

Testing for access to resources assigned to a different role
Analyze, for example, an application that uses a shared directory to store temporary PDF files for different users. Suppose that documentABC.pdf should be accessible only by the user test1 with roleA. Verify if user test2 with roleB can access that resource.

Result Expected:
Execute administrative functions or access administrative resources as a standard user.

Gray Box testing and example

Testing for Topic X vulnerabilities:
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Result Expected:
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References

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