Zeta Producer Desktop CMS 14.2.0 Code Execution / File Disclosure

`SEC Consult Vulnerability Lab Security Advisory < 20180712-0 >  
=======================================================================  
title: Remote Code Execution & Local File Disclosure  
product: Zeta Producer Desktop CMS  
vulnerable version: <=14.2.0  
fixed version: >=14.2.1  
CVE number: CVE-2018-13981, CVE-2018-13980  
impact: critical  
homepage: https://www.zeta-producer.com  
found: 2017-11-25  
by: P. Morimoto (Office Bangkok)  
SEC Consult Vulnerability Lab   
  
An integrated part of SEC Consult  
Europe | Asia | North America  
  
https://www.sec-consult.com  
  
=======================================================================  
  
Vendor description:  
-------------------  
"With Zeta Producer, the website builder and online shop system for Windows,   
you can create and manage your website locally, on your computer.   
Get without expertise in 3 steps to your own homepage: select design,   
paste content, publish website. Finished."  
  
Source: https://www.zeta-producer.com/de/index.html  
  
  
Business recommendation:  
------------------------  
The vendor provides a patched version which should be installed immediately.  
  
Users of the product also need to verify that the affected widgets are updated in  
the corresponding website project! It could be necessary to rebuild the whole project  
or copy the new widgets to the website projects. For further information consult the  
vendor.  
  
Furthermore, an in-depth security analysis is highly advised, as the software may be  
affected from further security issues.  
  
  
Vulnerability overview/description:  
-----------------------------------  
1) Remote Code Execution (CVE-2018-13981)  
The email contact functionality of the widget "formmailer" can upload files  
to the server but if the user uploads a PHP script with a .php extension   
then the server will rename it to .phps to prevent PHP code execution.  
  
However, the attacker can upload .php5 or .phtml to the server without any   
restriction. These alternative file extensions can be executed as PHP code.   
  
Furthermore, the server will create a folder to store the files, with a  
random name using PHP's "uniqid" function.  
  
Unfortunately, if the server permits directory listing, the attacker  
can easily browse to the uploaded PHP script. If no directory listing is   
enabled the attacker can still bruteforce the random name to gain remote   
code execution via the PHP script as well. Testing on a local server it   
took about 20 seconds to brute force the random name. This attack will   
be slower over the Internet but it is still feasible.  
  
Also, if the user runs the Zeta Producer Desktop CMS GUI client locally,  
they are also vulnerable because the web server will be running on TCP port 9153.  
  
The root cause is in the widget "formmailer" which is enabled by default.  
The following files are affected:  
- /assets/php/formmailer/SendEmail.php  
- /assets/php/formmailer/functions.php  
  
  
2) Local File Disclosure (CVE-2018-13980)  
If the user enables the widget "filebrowser" on Zeta Producer Desktop CMS an   
unauthenticated attacker can read local files by exploiting path traversal issues.   
  
The following files are affected:  
- /assets/php/filebrowser/filebrowser.main.php  
  
  
Proof of concept:  
-----------------  
1) Remote Code Execution (CVE-2018-13981)  
The following python script can be used to exploit the chain of vulnerabilities.  
[.. code has been removed to prevent misuses ..]  
  
When the script is executed, a PHP script (shell) will be uploaded automatically.  
# $ python exploit.py  
# [+] injecting webshell to http://target/assets/php/formmailer/SendEmail.php  
#  
# 5a1a5bc991afe  
# 5a1a5bc99453a  
# 10812  
# [*] Found : http://target/assets/php/formmailer/upload_5a1a5bc992772/sectest.php5  
# uid=33(www-data) gid=33(www-data) groups=33(www-data)  
  
  
2) Local File Disclosure (CVE-2018-13980)  
The parameter "file" in the "filebrowser.main.php" script can be exploited to read  
arbitrary files from the OS with the privileges of the web server user.  
Any unauthenticated user can exploit this issue!  
  
http://target/assets/php/filebrowser/filebrowser.main.php?file=../../../../../../../../../../etc/passwd&do=download  
http://target/assets/php/filebrowser/filebrowser.main.php?file=../../../../../../../../../../etc&do=list  
  
  
Vulnerable / tested versions:  
-----------------------------  
The following versions have been tested which were the latest version available   
at the time of the test:  
  
Zeta Producer Desktop CMS 14.1.0  
Zeta Producer Desktop CMS 14.2.0  
  
Source:   
- https://www.zeta-producer.com/de/download.html  
- https://github.com/ZetaSoftware/zeta-producer-content/  
  
  
Vendor contact timeline:  
------------------------  
2017-11-29: Contacting vendor through [email protected] and various other  
email addresses from the website. No reply.  
2017-12-13: Contacting vendor again, extending email address list, no reply  
2018-01-09: Contacting vendor again  
2018-01-10: Vendor replies, requests transmission of security advisory  
2018-01-10: Sending unencrypted security advisory  
2018-07-02: There was no feedback from the vendor but the version 14.2.1 fixed  
the reported vulnerabilities.  
2018-07-12: Public advisory release.  
  
  
Solution:  
---------  
Upgrade to version 14.2.1 or newer. See the vendor's download page:  
  
https://www.zeta-producer.com/de/download.html  
  
Users of the product also need to verify that the affected widgets are updated in  
the corresponding website project! It could be necessary to rebuild the whole project  
or copy the new widgets to the website projects. For further information consult the  
vendor.  
  
  
Workaround:  
-----------  
Remove "formmailer" and "filebrowser" widgets.  
  
  
Advisory URL:  
-------------  
https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
SEC Consult Vulnerability Lab  
  
SEC Consult  
Europe | Asia | North America  
  
About SEC Consult Vulnerability Lab  
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It  
ensures the continued knowledge gain of SEC Consult in the field of network  
and application security to stay ahead of the attacker. The SEC Consult  
Vulnerability Lab supports high-quality penetration testing and the evaluation  
of new offensive and defensive technologies for our customers. Hence our  
customers obtain the most current information about vulnerabilities and valid  
recommendation about the risk profile of new technologies.  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
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EOF P. Morimoto / @2018  
  
`