Blue, while possibly the most simple machine on Hack The Box, demonstrates the severity of the EternalBlue exploit, which has been used in multiple large-scale ransomware and crypto-mining attacks since it was leaked publicly.

FriendZone is an easy difficulty Linux box which needs fair amount enumeration. By doing a zone transfer vhosts are discovered. There are open shares on samba which provides credentials for an admin panel. From there, an LFI is found which is leveraged to get RCE. A cron is found running which uses a writable module, making it vulnerable to hijacking.