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 info@zeta-producer.com 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. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://www.sec-consult.com/en/career/index.html Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://www.sec-consult.com/en/contact/index.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF P. Morimoto / @2018