Tags: glob null-byte-poisoning regex
Rating:
tl;dr:
1. Notice the badchars are checked in order and we can do `{[,/}` to read any file
2. Notice that `Dir.glob` removes anything before nullbyte, so we can strip the `.` at the front
Full writeup: https://github.com/p4-team/ctf/tree/master/2019-10-19-seccon/fileserver
