Advent of CTF 2024 — Day 13: Disoriented Santa

Still going strong, we’re onto Day 13 now! We’re now here with another OSINT challenge that involves using OpenStreetMap API and https://overpass-turbo.eu/, with one of the clues giving us a hint to use this query: This query was extremely useful in helping me get a baseline on how to create my search query.

[out:json][timeout:25];

node["charge"="<charge>"]["tourism"="<tourism>"]();

out body;
>;
out skel qt;

So we have this challenge where we have to find where Santa is, given this data we know that:

• Santa is in a history museum.
• The history museum costs 3 EUR for entry.
• The library is within ~1km of the museum.

This challenge at first proved to be quite difficult since I was not familiar with the Overpass Query Language, but it was easily supplemented after checking the API and by watching this video.

[embed]

[embed]Map features OpenStreetMap represents physical features on the ground (e.g., roads or buildings) using tags attached to its basic…wiki.openstreetmap.org

I didn’t really know how to use this so I didn’t use it lol.

This one essentially helped narrow down which museum it was.

My final query ended up looking like this, I managed to get three results so I just copy & pasted them each hoping it would be the flag before refining my query, since they were already similar

[out:json][timeout:25];

//FIND MUSEUM SPECIFICALLY OF TYPE "HISTORY"
node["tourism"="museum"]["museum"="history"]["charge"="3 EUR"]({{bbox}});
out body;
//FIND NEAR LIBRARY
node(around:1000)["amenity"="library"];
out body;
>;
out skel qt;

It was essential for me to understand the question again, I was stuck doing this for a few hours since I wasn’t reading the question properly, it says that he was stuck in a “history museum” so instead of just searching for a museum, I had to carefully search for a “history” museum.

This is our flag csd{48.204,7.364} — cheers and onto the next challenges ahead!