Summary
Registry,a Linux box created by HackTheBox user thek, was an overall medium to hard difficulty box.The inital enumeration expose a docker registry from where you can download an image which contain a ssh key for the user.SSH into the box we find nginx config which point us to bolt db. Cracking the password in bolt db we get access to bolt webserver and we can upload a ph0ny shell and get www-data
user which have access to run restic backup as root. using that we can get root.