Another interesting VM from @egre55 Thanks for your imagination and work 
Initial Foothold
Credentials are not always necessary... Try to identify the right OS version.
After, Google can help you to find your new friend and don't be afraid by him... (some are nice, like Rémy, a great Chef)
And wait: have you looked everywhere enough? sure?...
User & Root
You got finally another reverse shell, well.
Now, try to find a way to read them... You have the power and the right users to do it.