Day 24 - Mastermind

Question: Who reserved the deck chairs?

Solution

From the picture, we can see that the seats were reserved by someone called "bknotbmoka1337". It sounds like a username. We can search whether that username has been used in any website previously. Here, I used username.social, but there are plenty of similar tools.

Most of the results, however, are false positives. But we can be sure that the GitHub account definitely exists by visiting it.

There's a repository that contains just one pdf file.

As the contents of the file itself is not necessarily useful right now, we might want to look at the file's metadata. I used exiftool to extract the metadata of the file.

The mastermind behind all of this, is "Big Red Joulupukki". Which means that The Thief... was Santa himself all along!

Flag: Big Red Joulupukki