Steganography

Platform TJCTF 2026 (Thomas Jefferson CTF) Difficulty Easy → Hard OS Mixed: Linux, macOS ARM64, WebAssembly, Network captures Tags JWT crafting, SSRF via URL normalization, Zip Slip, RSA parity oracle, ECDSA timing/Minerva, invalid-curve attacks, Chebyshev matrix exponentiation, ReDoS as side channel, pickle exploitation, PCK parsing, polyglot files, RTP LSB steganography TJCTF 2026 was the kind of multi-day event that rewards breadth — twenty-one challenges spread across web, reverse engineering, cryptography, forensics, and misc, with no single technique cracking more than two boxes. This writeup is the consolidated solve log: one paragraph of prompt + trick + solution per challenge, the actual flag, and the moments worth quoting verbatim. ...

Platform THCON 2026 (Toulouse Hacking Convention) Difficulty Medium OS Steganography Tags Frequency analysis, binary encoding, PNG carving, LSB steganography PNG3D is the steganography challenge that rewards the simplest possible recon move — frequency analysis — and punishes anyone who tries fancy stego tools first. The challenge file is ~40 MB of UTF-8 text that looks like noise; the trick is to notice that two specific characters make up nearly all of it, in roughly equal numbers, and that’s a binary encoding screaming to be decoded. ...