Mastering Bulk API Access Control Testing with Burp Suite Auth Analyzer

Introduction

As software security becomes a critical challenge, API access‑control (broken access control) testing is essential for testers. This article demonstrates a fast and efficient method using Burp Suite's Auth Analyzer plugin for bulk testing of access‑control vulnerabilities.

Broken Access Control Overview

Broken Access Control (BAC) is a common web‑application vulnerability listed as the second most severe issue by OWASP. It occurs when insufficient permission checks allow attackers with low‑privilege accounts to bypass controls and access or manipulate higher‑privilege resources.

Typical Types

Unauthorized Access : Gaining a function permission without any account.

Horizontal Privilege Escalation : Using a low‑privilege account to act on data belonging to other accounts with the same level.

Vertical Privilege Escalation : Elevating from a low‑privilege account to higher privileges.

Burp Suite Overview

Burp Suite is an integrated penetration‑testing platform offering modules such as Dashboard, Target, Proxy, Intruder, Repeater, Sequencer, Decoder, etc. While the Repeater module can manually verify a single API for access‑control issues, it is inefficient for bulk testing.

Auth Analyzer Plugin

The Auth Analyzer extension adds bulk API access‑control testing capabilities. Install it from the BApp Store and use it to repeat requests across multiple endpoints and analyze permission differences automatically.

Installation Steps

Open Extensions → BApp Store in Burp Suite and download the Auth Analyzer plugin.

After installation, the plugin appears in the Burp Suite interface.

Performing Bulk Access‑Control Testing

In Proxy → Intercept, turn off interception ( Intercept is off) to allow traffic capture without interruption.

Open Burp's built‑in browser and log in with a high‑privilege user to generate traffic.

Capture the API requests generated during the high‑privilege session.

Select the target APIs, right‑click, and choose Auth Analyzer → Repeat all requests to send the same calls with the current (high‑privilege) credentials.

Switch to the Auth Analyzer tab to view analysis results, which highlight differences indicating potential over‑privileged access.

Export the findings as a CSV or HTML report for documentation.

Review the exported report, which lists each tested endpoint, the request/response details, and the identified access‑control issues.

Conclusion

After fixing the identified access‑control vulnerabilities, repeat the above steps to verify remediation. Using Burp Suite's Auth Analyzer plugin streamlines bulk API permission testing, improving both the depth and efficiency of security assessments.