What is HTTP Downgrading, why use it, and how does it work? HTTP/2 is default for most web apps these days, however, it's not uncommon for backend servers to still use HTTP/1.1 causing parsing mismatches between frontend and backend. And that's where HTTP downgrading comes in! But what is... it? HTTP downgrading is the process of forcing a request to be processed under HTTP/1.1 instead of HTTP/2. This allows you to manipulate how the frontend and backend servers interpret requests and exploit vulnerabilities unique to HTTP/1.1 parsing such as Content-Length Transfer-Encoding (CL.TE) attacks. How to downgrade HTTP/2 to HTTP/1.1 using Burp Suite 1️⃣ Open Burp Suite and Navigate to Proxy → HTTP History 2️⃣ Locate the request that is currently using HTTP/2. 3️⃣ Send the Request to Repeater 4️⃣ In the Repeater tab, open the "Inspector" panel → Request Attributes → Protocol 5️⃣ Change HTTP Version to HTTP/1.1 6️⃣ Click "Send" in Repeater. If successful, you should receive a valid response, confirming the server accepts HTTP/1.1. And that's it! You've just downgraded the HTTP protocol and confirmed that the frontend server accepts HTTP/1.1! 🥳 You are now ready to smuggle requests! If you want to learn how to exploit this, we've got a Web Academy Lab you need to check out: Thanks for reading! #requestsmuggling #cybersecurity #BurpSuite #hacking #infosecshow more

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