DEF CON 32 - Gotta Cache ‘em all bending the rules of web cache exploitation - Martin Doyhenard

In recent years, web cache attacks have become a popular way to steal sensitive data, deface websites, and deliver exploits. We've also seen parser inconsistencies causing critical vulnerabilities like HTTP Request Smuggling. This raises the question: what happens if we attack web caches' URL-parsers? In this session, I'll introduce two powerful new techniques that exploit RFC ambiguities to bypass the limitations of web cache deception and poisoning attacks. First, I'll introduce Static Path Deception, a novel technique to completely compromise the confidentiality of an application. I’ll illustrate this with a case study showing how such a breach can be replicated in environments like Nginx behind Cloudflare. Next, I'll present Cache Key Confusion, and show how to exploit URL parsing inconsistencies in major platforms, including Microsoft Azure Cloud. I’ll then show how to achieve arbitrary cache poisoning and full denial of service. Finally, I'll reveal how to supercharge these vulnerabilities with a live demo that blends Cache Key Confusion with a “non-exploitable” open redirect to execute arbitrary JS code for complete site takeover. Attendees will depart armed with a set of innovative techniques, along with a definitive methodology to find and exploit these and other URL or HTTP discrepancies.