RMTP Example

RMTP is a protocol that has length checks in the requests and the responses. If you want to change data in realtime it is very difficult to do by hand. You can use the Python Mangler to do all the heavy lifting for you.

In this test I made a few requests and used Burp's comparer to see which bytes changed depending on the message I sent through Nope. I've highlighed them in the following screenshot.

Using just the mangle function we can create offsets that will automatically update the length boundaries when we want to replace a string. In this example I send from the client the text "ReplaceMe" and the mangle function will match and replace this with our payload. It will then automatically update the length checks in the request.

Notice the text gets replaced as the traffic flows through the proxy.