Silo focuses mainly on leveraging Oracle to obtain a shell and escalate privileges. It was intended to be completed manually using various tools, however Oracle Database Attack Tool greatly simplifies the process, reducing the difficulty of the machine substantially.

Bastard is not overly challenging, however it requires some knowledge of PHP in order to modify and use the proof of concept required for initial entry. This machine demonstrates the potential severity of vulnerabilities in content management systems.

Optimum is a beginner-level machine which mainly focuses on enumeration of services with known exploits. Both exploits are easy to obtain and have associated Metasploit modules, making this machine fairly simple to complete.

Node focuses mainly on newer software and poor configurations. The machine starts out seemingly easy, but gets progressively harder as more access is gained. In-depth enumeration is required at several steps to be able to progress further into the machine.

SolidState is a medium difficulty machine that requires chaining of multiple attack vectors in order to get a privileged shell. As a note, in some cases the exploit may fail to trigger more than once and a machine reset is required.