Original Post: Exploiting and Securing File Upload Traverser Vulnerabilities: A Practical Guide | by Gokulvinesh | Sep, 2024
The content of the blog discusses the "File Upload Traverser" vulnerability encountered by the author, highlighting its critical security implications and expounding on its potential threats. Here’s a summary:
Introduction:
- Author: Gokulvinesh
- Focus: Explores the File Upload Traverser vulnerability encountered during web security research, using Burp Suite for exploitation. Emphasizes the importance of proper file path validation.
Definition:
- File Upload Traverser: A vulnerability where attackers can manipulate file paths to upload files to arbitrary directories on a server using traversal sequences (e.g.,
../). This results from insufficient validation or sanitization of file paths provided by users.
Impacts:
- Security Risks: Can lead to remote code execution (RCE), file overwriting (potentially replacing critical system files or configurations), unauthorized file uploads (e.g., webshells), and data breaches.
Exploitation Steps:
- Upload and Capture: Upload a file and capture the request in Burp Suite.
- Verify Location: Confirm where the file is uploaded (e.g., "assets/upload_folder/uploads/hello.txt").
- Directory Traversal: Re-upload with manipulated file paths (e.g., "../../../hello.txt") to perform directory traversal.
Tools:
- Automated Testing: Use Burp Suite’s File Upload Traverser extension for automated vulnerability tests.
Prevention:
- Validation and Sanitization: Block traversal sequences and validate file paths.
- Storage: Store uploads in non-executable directories.
- File Type Restriction: Use a whitelist for allowed file types and rename files.
- Permission Controls: Implement access restrictions.
- Content Validation: Ensure uploaded files do not contain malicious code.
The blog explores practical steps for exploiting the vulnerability and recommends solutions for securing web applications against such threats.
Go here to read the Original Post