HASBLCTF 2026 Forensics Writeup: All 5 Challenges Solved
Platform HASBL CTF 2026 Difficulty Mixed (Easy → Medium) OS Jeopardy — Forensics (Linux toolchain) Tags QR-code decoding with Reed-Solomon tolerance, JPEG metadata extraction (EXIF, COM, XMP), base64/base32 encoding fingerprints, bit-stream-to-JPEG reconstruction, magic-byte surgical repair, file-header recognition HASBL CTF 2026 is a multi-category jeopardy event with Reverse Engineering, Pwn, Web, and Forensics tracks. This writeup is dedicated to the Forensics track — the five forensics challenges (Quick Response, Logo, Digits, our sweet cat, Pamuk, and The Magic of "Magic Numbers") were all solved, and each one teaches a different file-forensics primitive: QR-code decoding despite a visual overlay, JPEG metadata extraction across EXIF and COM segments, bit-stream-to-JPEG byte reconstruction, base64-wrapped JPEG with hex content, and surgical magic-byte repair plus XMP metadata walking. ...