Cronos begins with a simple DNS enumeration to find a hidden subdomain with a login page. Then we exploit SQL and command injection vulnerabilities to get a shell. This machine requires knowledge of how cron jobs work to get root. Easy and fun machine!
Mirai was a very fun box! It requires thinking outside the box and compiling all information you have to guess some credentials. The root part requires knowledge of how Linux handles external devices to complete.
Bank is an easy machine. It requires some scripting and basic Linux enumeration skills to complete.