How I Discovered an HTTP Request Smuggling Vulnerability in a Major Web Console

During one of my recent security assessments, I uncovered a significant vulnerability in a widely-used web console that could potentially allow malicious actors to manipulate HTTP requests undetected. This blog post details how I identified the issue, the steps I took to confirm its existence, and the potential impacts it could have on the affected platform.

What is HTTP Request Smuggling?

HTTP Request Smuggling (HRS) is a sophisticated web security vulnerability that occurs when different servers or intermediaries (like proxies or load balancers) interpret HTTP requests inconsistently. This inconsistency can be exploited by attackers to “smuggle” malicious requests through the server chain, bypassing security measures and executing unauthorized actions.

In essence, HRS takes advantage of discrepancies in how Content-Length and Transfer-Encoding headers are processed by different components within a web infrastructure. When not properly managed, this can lead to various attacks, including session hijacking, cache poisoning, and even full system compromise.

Identifying the Vulnerability