Anti-Slop CTF 2026 OSINT Writeup: Observers Are All You Need + Geoguessr
Seventh and last per-category post in the Anti-Slop CTF 2026 series. The earlier ones cover web, reverse, pwn, crypto, blockchain, and the misc Baby Maths prompt-injection trap. This one walks the two OSINT challenges in the same step-by-step format. Observers Are All You Need is the GitHub-pivot variant of OSINT: read a cryptic prompt, identify the right project to pivot to, then walk the project’s public artifact trail (profile, issues, PRs) to assemble the flag in three fragments. Geoguessr is the cooler hybrid: ten panoramas look like a pure geolocation puzzle, but the web client uses each location as a key derivation input for Shamir-shared decryption, and you only need 9 of 10 locations to recover the flag. Once the verification crypto is understood, you don’t need pixel-perfect coordinates. You need the correct H3 resolution-8 cell. ...