Web App Pentesting - HTTP Headers & Methods

Introduction

This tutorial covers essential concepts of web application penetration testing, focusing on HTTP headers and methods, particularly the potential abuse of the PUT method. Understanding these elements is crucial for identifying vulnerabilities in web applications and enhancing your cybersecurity skills.

Step 1: Understand HTTP Headers

HTTP headers are key-value pairs sent in HTTP requests and responses. They provide essential information about the request or response.

• Request Headers: Sent by the client to the server, they include:

  • Host: Specifies the domain name of the server.
  • User-Agent: Identifies the client software making the request.
  • Accept: Indicates the media types that are acceptable for the response.

• Response Headers: Sent by the server back to the client, they include:

  • Content-Type: Indicates the media type of the resource.
  • Cache-Control: Specifies directives for caching mechanisms.
  • Set-Cookie: Used to send cookies from the server to the client.

Practical Tip

Always inspect HTTP headers using browser developer tools or tools like Postman or cURL to understand how they affect web application behavior.

Step 2: Explore HTTP Methods

HTTP methods define the action to be performed on a resource. The most common methods include:

• GET: Retrieve data from the server.
• POST: Send data to the server to create/update resources.
• PUT: Update a current resource or create a new one if it doesn't exist.
• DELETE: Remove a resource from the server.

Common Pitfalls

• Misconfigured servers may allow unsafe methods (like PUT or DELETE) that can lead to vulnerabilities.
• Not properly validating user input can lead to security issues when using methods like POST and PUT.

Step 3: Focus on the PUT Method

The PUT method can be particularly dangerous if misconfigured, allowing attackers to upload files or overwrite existing resources.

How to Test for PUT Method Vulnerabilities

1. Check if PUT is Enabled: Use tools like cURL to test if the server accepts PUT requests.

   curl -X PUT http://targetwebsite.com/resource -d "data"
   

2. Upload Malicious Files: If PUT is enabled, try to upload a script or file that could give you remote access to the server.
3. Analyze Server Responses: Observe the server's response to determine if the upload was successful or if any restrictions are in place.

Real-World Application

Understanding and testing the PUT method's security can help prevent unauthorized file uploads, which could lead to data breaches or server compromises.

Conclusion

In this tutorial, we covered essential HTTP headers and methods, emphasizing the risks associated with the PUT method in web application pentesting. By understanding these concepts, you are better equipped to identify potential vulnerabilities in web applications. Next steps could include further exploring HTTP methods in various contexts or deepening your knowledge of other web security topics.