This module exploits a SQL Injection vulnerability in the `com_fields` component which was introduced to the core of Joomla in version 3.7.0.
With the SQLi, it's possible to enumerate cookies of Administrator and Super User users, and hijack one of their sessions. If no Super User is authenticated, the RCE portion will not work. If a session hijack is available, one of the website templates is identified, and our payload is added to the template as a new file, and then executed.
[*] 172.22.222.122:80 - Following redirect to [ /joomlatest/administrator/index.php?option=com_templates&view=template&id=503&file=L3pNOFp2SUFBd3hFLnBocA%3D%3D ]