DIVER OSINT CTF 2026 Writeup
Writeup for challenges solved during DIVER OSINT CTF 2026. My first CTF experience, focusing on OSINT techniques and tools.
Overview
This writeup covers the challenges I solved during the DIVER OSINT CTF 2026, which was my first CTF experience. The competition focused on OSINT (Open Source Intelligence) techniques and tools, and I learned a lot about different methods for gathering information from publicly available sources.
- Team: Bao Bao
- User: yuerei
- Final Standing: 239th place
- Focus Areas: OSINT
Introduction
read_qr (100pt / 547 solves)
What URL is stored in this QR code? If it is https://x.com/DIVER_OSINT_CTF, the flag should be Diver26{ https://x.com/DIVER_OSINT_CTF }.
Once I downloaded the image I immediately scanned it with my phone, which revealed the URL https://qr.intro26.workers.dev/q/y0u_r34d_7h3_qr_wi7h0u7_4cc3ss.
The flag was then formatted as:
DIVER26{https://qr.intro26.workers.dev/q/y0u_r34d_7h3_qr_wi7h0u7_4cc3ss}.
momo (100pt / 558 solves)
I took a photo of an aircraft in April 2026, but I forgot to photograph its registration number. Find out and answer the registration number of the aircraft shown in the photo. If the registration number is JA380A, the flag should be Diver26{JA380A}.
I found this website to see the special livery of the aircraft:
Special Colors / Stickers, and I saw one with the same design as the challenge image, with Remark lsd, "Taihei Dengyo" sticker.
It’s JA823P
Diver26{JA823P}
owner (100pt / 590 solves)
Answer the country which owns this vehicle in English. For example, if it is Japan, the flag should be Diver26{Japan}.
A diplomat number 外 (gaikoku, meaning foreign). Googling it will come out with Australia.
Diver26{Australia}
8pm (100pt / 387 solves)
What was the first specific facility featured in the news program broadcast on Korean Central Television at 8:00 PM (local time) on July 2, 2026? Answer using the OpenStreetMap Way ID. However, provide the Way ID representing the entire site, not an individual building. For example, if the way number is 1234567890, the flag should be Diver26{1234567890}.
Searched for KCNA Watch and found the broadcast on July 2, 2026, at 8:00 PM.
The building in the image is the Pyonyang Elementary School, which has the OpenStreetMap Way ID 1131937005.
Diver26{1131937005}
misc
nui (100pt / 242 solves)
Searched for the image using Google Lens and found a Nasa webpage for the original image.
Downloaded it and checked the metadata using https://exif.tools/ and found the following information:
Make samsung
Model Galaxy S23 Ultra
Create Date 2026-01-28T07:48:28.000Z
Date Time Digitized 2026:01:28 14:48:28
Date Time Original 2026-01-28T07:48:28.000Z | 2026:01:28 14:48:28Diver26{20260128_Galaxy S23 Ultra}
Conclusion
This competition was a great for my first CTF and OSINT experience. I learned a lot about different techniques and tools. Looking forward to participating in more CTFs in the future and improving my skills further.
Did not know Swimmer exist… maybe next time I will participate in Swimmer CTF.
If you want to read more from my teammates, you can check them out on their blog site: