Solution. The file has a lot of hex numbers separated by commas and new lines. I changed it to be like this: \x50\x4B\x03\x04\x14\
Inside, you won't find plain text. You are greeted by a password-protected PDF. strojno_kol.zip
The key to unlocking the secrets? A subtle, poetic hint: "butterfly" . Solution
VULNCON CTF 2020 - All I know was zip writeup - Víctor Colombo strojno_kol.zip