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competition-stego-media

competition-stego-media

github.com/zhaoxuya520Security43.7k94 installsUpdated 5w ago
Repository

About competition-stego-media

A CTF skill for investigating steganography in media containers, hidden channels, and appended payloads. It is intended as a specialization after `$ctf-sandbox-orchestrator` establishes the sandbox and evidence priorities.

Key features

  1. 01Container and metadata inspection
  2. 02Evidence-ranked channel analysis
  3. 03Layered payload reconstruction
  4. 04Reproducible extraction tracking
  5. 05Final payload verification

Use cases

  1. 01Checking media files for appended archives
  2. 02Comparing alpha, palette, and LSB channels
  3. 03Tracing video frame or audio signal clues
  4. 04Preserving an extracted payload chain

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/zhaoxuya520/reverse-skill --skill competition-stego-media

After installing, type/competition-stego-mediain Claude Code to confirm it loaded.

Bundled filesagents/openai.yamlreferences/stego-media.md

Details

From the project README

Competition Stego Media

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the challenge lives inside a media container, hidden channel, or appended payload rather than a conventional crypto blob.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Confirm the real container type, dimensions, duration, codec, and chunk layout before guessing a hidden layer.
  2. Check metadata, thumbnails, sidecar files, and appended trailers before deeper signal-domain work.
  3. Rank candidate channels by evidence: alpha, palette, LSB, transform-domain residue, frame order, or container slack.
  4. Preserve each extracted layer separately so the transform chain stays reproducible.
  5. Stop when the hidden payload is reproduced, not merely suspected.

Workflow

1. Establish Container Truth
  • Inspect headers, chunk tables, EXIF or document metadata, container indexes, thumbnails, and file size anomalies.
  • Compare declared format against observed structure to catch polyglots, appended archives, or malformed trailers.
  • Record exact offsets, frame numbers, or channel boundaries that look promising.
2. Inspect Candidate Channels
  • Check alpha, palette order, RGB or YUV planes, LSBs, spectrogram features, document object streams, or video frame deltas.
  • Prefer evidence-driven attempts over brute forcing every transform.
  • Note whether the payload is plain bytes, another media layer, compressed data, or an encrypted blob.
3. Reconstruct The Hidden Payload Path
  • Keep the chain in order: container -> channel or carrier -> extraction -> decompression or decode -> final parse.
  • Separate extraction success from final interpretation; a channel hit is not the same as artifact recovery.
  • If the problem becomes primarily about cryptography after extraction, hand off to the broader crypto skill.

Read This Reference

  • Load references/stego-media.md for the media checklist, channel ranking guide, and evidence packaging.

What To Preserve

  • File structure facts: offsets, chunks, frame numbers, stream names, metadata keys, and trailer size
  • Intermediate extractions and the exact command or transform used to produce them
  • The final recovered payload and the channel that produced it

Comments

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