SANS Holiday Hack Challenge 2020: Unescape Tmux

Each year, the SANS and Counter Hack Challenges teams put together my favorite capture the flag (CTF) competition, the SANS Holiday Hack Challenge. The 2020 SANS Holiday Hack Challenge, featuring KringleCon 3: French Hens! was held at Santa’s newly renovated castle at the North Pole from December 10, 2020 to January 11, 2021. This is a walk-through for a terminal challenge from the event.

I met Pepper Minstix on the front lawn of Santa’s castle. He filled me in on his recent adventures with tmux but somehow he got detached from his session and…