DIVER OSINT CTF 2026 "stable" Writeup
Table of Contents
This article was automatically translated from Japanese by AI.
Challenge
Solution
Searching for the complete string returned only existing writeups, so I searched for just the beginning of the address with a query such as "0x5Ec2bb2D" -writeup. This returned a PolygonScan address page, showing that the string is an address on Polygon.
https://polygonscan.com/address/0x5Ec2bb2D56FC8CC4d05110211EcaBDC8fAe3B128
The Token Transfers section on PolygonScan shows that the address transacts in JPY Coin (JPYC). Most of the transactions are small incoming transfers, with dozens of transactions in its history.
Searching for "JPYCが使えるお店" leads to JPYCが使えるお店・場所マップ and JPYC-MAP.com. The JPYC payment usage page lists 千房 有楽町ビックカメラ支店 (Chibo Yurakucho Bic Camera Branch) among the shops with the highest transaction counts, making it a likely candidate based on the scale of its payment activity.
Searching for the shop name led to an article and video documenting an actual JPYC payment at the branch. The video shows a payment of 1,550 JPYC sometime around April 2026.
The target address’s PolygonScan history contains a transaction for exactly 1,550 JPYC at 03:09:11 UTC on April 13, 2026, corresponding to 12:09:11 JST. The matching amount and timestamp identify the address as the payment address of 千房 有楽町ビックカメラ支店.
Flag
Diver26{千房 有楽町ビックカメラ支店}