The OSINT challenge was released during the live-stream of the Security BSides Athens 2022 event, as part of the talk "Baby, Don't Forget My Number: OSINT using your phone's address book" [^1].
The description was simple, a simple trick discussed in the talk should be used to uncover as much information as possible from social media and instant messaging services for a given "target", for whom we only know the phone number: +30 694 942 2024. When enough information would be revealed, the challenge's goal -cryptically described as "the three wills"- would make sense. All of this was summarised in the slide below:
Note that a short video of this challenge description was played right after the talk and has also been uploaded on YouTube [^2]