cURL for Bypassing WAF: Advanced Techniques & Commands Every Hacker Should Know

Web Application Firewalls (WAFs) are designed to protect web applications from common web-based attacks like SQL injection, Cross-Site Scripting (XSS), and request flooding. However, attackers have developed techniques to bypass these security controls using various tools, and one of the most powerful tools in the hacker’s toolkit is cURL.

In this article, we will explore how cURL can be used to test and bypass WAFs by altering HTTP requests, headers, and payloads. We’ll focus on advanced techniques and commands that penetration testers and bug bounty hunters can apply to evade WAF protections.

What is cURL?

cURL (Client URL) is a command-line tool used for transferring data to or from a server, supporting protocols such as HTTP, HTTPS, FTP, and more. It is lightweight, powerful, and ideal for crafting custom requests to test how web applications respond to varying payloads.

Understanding WAF Bypasses

Before diving into commands, it’s important to understand how WAFs operate. WAFs analyze HTTP requests, filtering malicious payloads, and blocking harmful patterns. However, attackers often bypass WAFs using:

• Obfuscation of payloads.
• Header manipulation to trick WAFs.
• Encoding to bypass signature detection.
• Rate limiting circumvention.