Autoswagger: Open-Source Tool Detects API Authorization Flaws Before Attackers Do

Exposed API documentation has become a prime target for threat actors, providing a clear blueprint of system vulnerabilities. Intruder’s newly released Autoswagger tool addresses this growing security gap by automatically detecting broken access controls in OpenAPI/Swagger implementations before malicious actors can exploit them. The open-source solution, released on GitHub on July 22, 2025, has already gained attention from security professionals for its comprehensive approach to API security testing¹.

Executive Summary for Security Leadership

For time-constrained executives, Autoswagger represents a significant advancement in API security automation. The tool specifically targets authorization flaws that accounted for 40% of API-related breaches in 2025 according to Verizon’s DBIR⁶. Unlike manual testing methods, Autoswagger systematically identifies endpoints missing proper authentication checks, sensitive data exposure, and schema misconfigurations across entire API ecosystems.

Problem: API documentation often inadvertently exposes endpoints with broken access controls
Solution: Automated scanning of OpenAPI/Swagger implementations for authorization flaws
Key Benefit: Identifies vulnerabilities before attackers can weaponize exposed documentation
Deployment: Open-source Python tool with CLI interface, requiring minimal setup
Impact: Addresses one of the most common API security gaps with verifiable results

Technical Capabilities and Workflow

Autoswagger operates through a multi-phase discovery process that mirrors how attackers probe API implementations. The tool first attempts to locate OpenAPI specification files through direct paths, then scans for Swagger UI interfaces, and finally employs brute-force techniques against common schema locations³. This comprehensive approach ensures maximum coverage of potential documentation exposure points.

Once documentation is located, Autoswagger tests each endpoint using a sophisticated validation system. By default, it checks GET methods but can extend to POST, PUT, and DELETE operations with the -risk flag. The tool compares response codes against expected authentication requirements, flagging any endpoints that return 200 OK when they should require authentication⁴.

Detection and Analysis Features

The tool incorporates Microsoft Presidio for PII detection and custom regex patterns for identifying sensitive data like API keys and tokens. Response size analysis helps spot potential data leaks, with flags triggered for responses exceeding 100kB or containing more than 100 JSON elements. These detection mechanisms work in concert to prioritize the most critical findings for remediation teams².

Output options include both human-readable CLI tables and machine-parsable JSON, facilitating integration with existing security workflows. The -product mode filters results to show only endpoints with confirmed sensitive data exposure, while -stats provides detailed scan metrics for performance tuning and reporting purposes.

“These flaws are so easy to exploit, you could teach someone with no technical background how to do it in a day.”
– Chris Wallis, CEO of Intruder⁵

Practical Implementation

Getting started with Autoswagger requires basic Python environment setup. The installation process follows standard open-source practices:

git clone https://github.com/intruder-io/autoswagger.git
cd autoswagger
pip install -r requirements.txt
python3 autoswagger.py <target_url> [flags]

For comprehensive testing, security teams should consider running scans with both standard and advanced flags:

Flag	Purpose
`-risk`	Tests non-GET methods (POST/PUT/DELETE)
`-b`	Brute-forces parameter values
`-product`	Outputs only endpoints with PII/secrets
`-rate N`	Sets request rate limit (requests per second)

Security Implications and Best Practices

The release of Autoswagger highlights the ongoing challenges in API security, particularly around documentation exposure. Historical incidents like the 2022 Optus breach demonstrate the potential consequences of API authorization flaws, with damages reaching $140 million AUD⁶. Security teams should incorporate Autoswagger into their regular testing regimens, particularly before API deployments and after significant updates.

For organizations using OpenAPI/Swagger documentation, security professionals recommend:

Restricting documentation access to authenticated users
Implementing proper authorization checks on all endpoints
Regularly scanning for exposed documentation using tools like Autoswagger
Monitoring for unusual access patterns to documentation paths

Conclusion

Autoswagger fills a critical gap in API security tooling by automating the detection of authorization flaws that frequently go unnoticed until exploited. Its open-source availability lowers the barrier to entry for organizations of all sizes, while its comprehensive scanning capabilities meet enterprise security needs. As API-related breaches continue to rise, tools like Autoswagger will become essential components of modern security programs.

The security community has welcomed the tool’s release, with multiple industry publications covering its potential impact. With proper implementation and regular use, Autoswagger can help organizations significantly reduce their API attack surface and prevent costly breaches.