https://github.com/InverseIntegral/ctf_writeups/tree/master/google_2019/friend_space_book_plus_all_access_red_premium https://github.com/InverseIntegral/ctf_wri

https://github.com/InverseIntegral/ctf_writeups/tree/master/google_2019/friend_space_book_plus_all_access_red_premium https://github.com/InverseIntegral/ctf_writeups/tree/master/... - great write up of the solution here