401 and 403 Bypass Cheat Sheet for Penetration Testers

This 401 and 403 bypass cheat sheet is an essential guide for penetration testers looking to bypass these common access control errors. We’ll cover manual techniques and popular automated tools, such as Bulk 403 Bypass, byp4xx, bypass-403, ForbiddenPass, and Burp Suite extensions. This resource is optimized for the key phrases “401 bypass cheatsheet” and “403 bypass cheatsheet.”

Manual Techniques for 401 and 403 Bypass

1. Change HTTP Method: Experiment with different HTTP methods (GET, POST, PUT, DELETE) to bypass restrictions.
2. Alter URL Encoding: Manipulate URL encoding using double URL encoding, Unicode encoding, or mixed encoding to bypass access control.
3. Directory Traversal: Use “../” or “./” in the URL path to access restricted files and bypass directory restrictions.
4. Add Trailing Slash: Append a trailing slash (“/”) at the end of the URL path to bypass access control.
5. Case Manipulation: Modify the case of letters in the URL to bypass case-sensitive restrictions.
6. HTTP Headers Manipulation: Tweak headers like X-Forwarded-For, X-Originating-IP, or Referer to bypass IP or referrer restrictions.
7. URL Fragment: Attach a URL fragment (e.g., “#randomtext”) to bypass access control.

Automated Tools for 401 and 403 Bypass

1. Bulk 403 Bypass: A Python script to automate testing for common 403 bypass techniques. Access the tool at https://github.com/aardwolfsecurityltd/bulk_403_bypass.
2. byp4xx: A script that helps bypass 401 and 403 errors using various techniques. Find the tool at https://github.com/lobuhi/byp4xx.
3. bypass-403: A Python-based tool designed to bypass 403 Forbidden errors. Access the tool at https://github.com/iamj0ker/bypass-403.
4. ForbiddenPass: A tool focused on bypassing 403 Forbidden responses by testing different methods. Download the tool at https://github.com/gotr00t0day/forbiddenpass.
5. Burp Suite Extensions: Enhance Burp Suite with extensions, such as Autorize, to help bypass 401 and 403 errors. Access the extension at https://portswigger.net/bappstore/444407b96d9c4de0adb7aed89e826122.

Additional Resources for 401 and 403 Bypass

1. OWASP: The Open Web Application Security Project (OWASP) provides a wealth of information on web application security, including guidance on bypassing access controls. Visit https://www.owasp.org for more information.
2. HackTricks: An excellent resource for penetration testing techniques, including bypassing 401 and 403 errors. Access the guide at https://book.hacktricks.xyz/network-services-pentesting/pentesting-web/403-and-401-bypasses.

Remember to always obtain proper authorization before conducting any penetration tests. This cheat sheet is intended for educational purposes and to enhance the security of web applications.