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.

Sunday is a fairly simple machine, however it uses fairly old software and can be a bit unpredictable at times. It mainly focuses on exploiting the Finger service as well as the use of weak credentials.

Nineveh is not overly challenging, however several exploits must be chained to gain initial access. Several uncommon services are running on the machine and some research is required to enumerate them

Nibbles is a fairly simple machine, however with the inclusion of a login blacklist, it is a fair bit more challenging to find valid credentials. Luckily, a username can be enumerated and guessing the correct password does not take long for most.