KalmarCTF 2026 0racle Writeup — Peeling Off Heaven's Gate and Self-Modifying Code to Brute-Force FNV-1a

Mon, 13 Jul 2026 10:00:00 +0900

Overview

KalmarCTF 2026 Rev challenge “0racle” (123pts). A Windows PE32 GUI application built with Free Pascal / Lazarus, themed around the “Oracle of Delphi”. Supplying the correct input displays “The gods are pleased”. The flag is the input itself (40 characters), and the goal is to work backward to the correct answer.

At first glance it looks like a plain “input check” challenge, but before you reach the validation logic there are three shells layered on top: XOR encoding → self-modifying code → Heaven’s Gate (32-bit→64-bit switch). We peel them off one at a time.

Fnv-1a on 万屋猫Labs

KalmarCTF 2026 0racle Writeup — Peeling Off Heaven's Gate and Self-Modifying Code to Brute-Force FNV-1a

Overview