This tweet shares a technique to bypass Web Application Firewalls (WAFs) by manipulating HTTP headers that represent client IP addresses. The command uses ffuf, a web fuzzing tool, to send requests with various IP-related headers such as X-Originating-IP, X-Forwarded-For, X-Remote-IP, X-Remote-Addr, and X-Client-IP all set to 127.0.0.1. These headers can sometimes fool WAFs into thinking the request originates from a trusted IP (like localhost), thereby bypassing security rules based on IP filtering.
The attack targets any WAF relying on IP-based filtering or IP reputation, making it potentially universal regardless of the specific WAF vendor. The payload involves injecting these headers to manipulate the perceived client IP and evade detection or filtering.
Key points:
– Uses multiple IP-related headers for redundancy.
– The localhost IP address (127.0.0.1) is used since it might be trusted by the WAF.
– The method can apply to various vulnerabilities, including access control bypass or rate limiting bypass, depending on the target setup.
– The example command integrates with ffuf to automate fuzzing with various file inputs (FUZZ).
This technique highlights how HTTP header manipulation can bypass security controls when those controls trust certain IP headers without proper validation.
For more insights, check out the original tweet here: https://twitter.com/_0b1d1/status/1934910687966605807