Not to be the guy who says this is easy because everyone is somewhere on the ladder but this one is a pretty big softball. 

The description states:  "This boot2root is a linux based virtual machine and has been tested using VMware workstation 14."  Works fine on VirtualBox which is what I used.

This is part of a new batch of servers that were dumped overnight and I had a few minutes to spare.

Kicking off with Nmap:

Couple of options but I quickly move to MySQL and I attempt to login using root and [no password]:  

I'm in.  I search for databases and I find:

Moving over to SSH:

While checking out the home directory for Mistic, I find:

While hunting crontab, I find:

I modify the script with a revers shell:

With my handler setup, I wait for it to execute:

It pops, I'm root, and I go for the flag! 

Simple as long as you understand what crontab does.  If not, that's a new lesson learned.