for future readers.
you probably ran spider scan then ajax spider scan, if you didn’t… do that .
then run active scan with
recurse mode on
, and on the same site and port and it will run for a while then it will show you a certain high alert that was already shown inside the module. copy that payload and modify it for flag.txt.
I guess I didn’t add a single word that destroys the try harder solution hopefully
but please see why the HUD doesn’t work for you and try to make it work, it is a must coupled with burp suite community.