Sharing is caring, but sometimes there are too many small projects that don't seem useful at first glance.
Posticum is a one of these projects created by a supposed sysadmin called Bakdyr. It appears suspicious... Can you look into it ?
Hints are everywhere ! Bruteforce and specialized tools won't help you here.
Good luck !
!! Do not clone this repo into a shared mount from Virtualbox or Vmware... For some reasons, it might no work !!
Ensure you have Docker and Docker Compose installed then :
git clone https://github.com/pun-private/chall-posticum
cd chall-posticum
docker-compose up
You can now access the challenge : http://127.0.0.1:40080