Lost in binaries

This challenge gives us the following text:

Ajutor, robotul nostru a fost pierdut! Am reusit sa obtinem fisierele acestea din cloud-ul robotului insa nu stiu daca sunt de ajuns ca sa-l putem recupera

Flag format: ABSO-CTF{[SHA-256(latitude)]}

Help, our robot was lost! We managed to get these files from the robot’s cloud but I don’t know if they are enough to recover it.

Flag format: ABSO-CTF{[SHA-256(latitude)]}

and an archive with 1 text file and 1 folder. The folder contents seemed more promising, but they ended up being useless. The folder contains 4 photos and a text file with the following text:

ultimele locatii prinse de camera foto a robotului, poate sunt de folos cuiva

the last locations captured by the robot’s camera may be useful to someone

the photos turned out to contain nothing: strings: nothing, exiftool: nothing, binwalk: nothing. After being stuck at this challenge the author dropped a hint:

Ai auzit vreodata despre turnuri gsm?

Have you ever heard of gsm towers?

This made me turn to the other text file, which contains the following text:

Here are some coordinates for the tallest statues in the world

21°50′16.8″N 73°43′08.7″E
33.7751°N 112.4510°E
22.0803°N 95.2893°E
35.9827°N 140.2203°E

// I don’t know what this is, we need to check where it came from


The first 4 lines are just coordinates to some statues around the world, nothing of significance here. The next 4 numbers are the key to this problem.

After searching on google for “gsm tower locator” I found this site, which helped me understand what those numbers meant. Selecting one of the points on the map and looking on the left side I can see that the number “226” from the text file is the MCC(Mobile country code) number, which is just some sort of country code for GSM antennas, the number “10” represents the MNC(Mobile Network Code), which identifies the specific provider, “16106” is the Region or LAC, and the last lumber “24757506” is the CID. Unfortunately, this site has no function to search for specific towers so I searched for another site.

After finding a site that has a search function and found the right antenna

The flag format is ABSO-CTF{[SHA-256(latitude)]}, so the flag is ABSO-CTF{70d24df72edc2c401971e8b942549c008cd21a83c75439cd151f8300c44bc7b4}

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