Below are all of the hints, ordered by the person that provided the hint.
Chatter?
From: Alabaster Snowball
sudo -l says I can run a command as root. What does it do?
User's Shells
From: Alabaster Snowball
On Linux, a user's shell is determined by the contents of /etc/passwd
Event IDs and Sysmon
From: Pepper Minstix
(Events and Sysmon)
PowerShell
SANS' PowerShell Cheat Sheet
Linux Path
From: SugarPlum Mary
Green words matter, files must be found, and the terminal's $PATH matters.
Frosty Keypad
From: Tangle Coalbox
One digit is repeated once, it's prime, and you can see which keys were used
Finding Bad in Web Logs
From: Wunorse Openslae
Do you see any LFI, XSS, Shellshock, or SQLi?