Three distinct image challenges, classic image steganography.

#1: strings
#2: binwalk
#3: replace and fixup the PNG header, decode QR code.

https://advancedpersistentjest.com/2017/11/27/writeups-lucifervm-notes-worth-a-thousand-words-the-never-ending-crypto-tuctf/

Original writeup (https://advancedpersistentjest.com/2017/11/27/writeups-lucifervm-notes-worth-a-thousand-words-the-never-ending-crypto-tuctf/).