We have just identified an important new eyewitness in a murder case, but they can't seem to remember where they were when it happened. We just know that they were drinking a coffee and watching out the window from across the street. They had the 3rd room on the corridor, on the 3rd floor. It is very important that we identify the EXACT location, with a very high accuracy (about 3 square meters), so our team can establish the witness' point of view of the crime scene. Failing to do so will allow the criminal to walk free.
Check the attached photo, it might contain some clues.
Flag format: CTF{SHA256(location)}
CTF{SHA256(///greeting.visual.stables)}
After doing some reverse image search with the given photo, I found out that it depicts Hotel “Casa Capșa” from Bucharest. Then, to get the location of the witnesses with 3 square meters accuracy, I used what3words.com, searching for the square representing the hotel across the street, looking on street view for the 3rd window of the 3rd floor.
The first thing I did with the given image was to use TinEye.com to gather some more info about where or what that building might be. The results looked like this:
https://lh5.googleusercontent.com/-a_PlaRqxJDN221wviHufoyvvvClpf-ZWIxLmo9WzixbfNMJFeol1E0OgCD430_BmmiUDJEl3p-EpHs6im08ecywwYWu7EXsyQkp8MBbjiTV7vYZIuLRTd5JceRJLXO7iSGVBvsI
So it turns out that it’s just an old photo of the well known Casa Capsa Hotel from Bucharest, Victoriei street. Then, considering that I needed 3 square-meters localization accuracy (and latitude-longitude coordinates can differ too much in this case to constitute a flag for a CTF), I just searched on Google for “3 square meters localization”. The first result was https://what3words.com/, and, because in the description the number 3 was mentioned several times, I was sure that I had found exactly what I needed.
Now I only had to guess which is the square for the building across the street, that contains the window of the 3rd room from the 3rd floor (the needed witnesses view). I just wandered around in street view for this:
https://lh5.googleusercontent.com/2IgqMO9bCx6qT4itIFPswcTwCkEUQvDq_fqwqi3KiR3CWEVuZdiCvA-Ia_4Fj2DSsNiXiSvD6FufOvEfGqHP2SLvXWT5lvEhHRg0-Hh77G5EUycNphgfGbhVwj039tieY8wKmHgA
Then, the square that covers that window area is:
https://lh3.googleusercontent.com/gHcfv6K4Yi1bQt-4hl8SSZnukp56xw97YqP-pJ_harfzazHGcIpR_isvsd19J4Lck4DmJC_WzhlJSciCevVZGlHoHxFl5Jwn4MexiUQ8ksbq-7FDO0HL8Nmx9NL20dQ7sdzZ0rHu