competition-file-parser-chain

A workflow for tracing how an uploaded file moves through an application’s parsers and converters. It covers archives, previews, format conversion, and deserialization, which means turning stored data back into objects or structures.

In plain words
What is it for?
It is for examining file imports, archive extraction, previews, converters, parser calls, and file-processing chains in CTF challenges.
Why use it?
It helps identify what happens to a file after upload, including hidden processing steps and parser choices.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/2233admin/reverse-skill-evolver/competition-file-parser-chain
Any agent
npx skills add 2233admin/reverse-skill-evolver --skill competition-file-parser-chain
Clone the repo
git clone --depth 1 https://github.com/2233admin/reverse-skill-evolver

Made for: Claude Code, Codex.

Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 613 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00109 $0.00613
Opus 5 $0.00055 $0.00307
Sonnet 5 $0.00022 $0.00123
Haiku 4.5 $0.00011 $0.00061

Measured 2d ago against content hash ac09fa9241fd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

competition-file-parser-chain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to competition-file-parser-chain — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

CTF-Sandbox-Orchestrator/competition-file-parser-chain/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Competition File Parser Chain

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 hard part is following a file from ingress through every parser, extractor, converter, or deserializer boundary that matters.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Preserve the original upload and every derived artifact separately.
  2. Map the chain in order: ingress, temp storage, archive extraction, format conversion, parser call, deserialization, and final consumer.
  3. Record filenames, MIME guesses, extensions, temp paths, and parser choices before mutating anything.
  4. Separate client-visible validation from backend parser behavior.
  5. Reproduce the smallest file-processing chain that yields the decisive branch or artifact.

Workflow

1. Map File Ingress And Derivation

  • Record request shape, multipart names, content type, filename, temp paths, upload staging, and storage keys.
  • Note every derived artifact: extracted archive member, converted preview, generated thumbnail, temp document, or deserialized object.
  • Keep original file and each derivative labeled separately.

2. Trace Parser And Conversion Boundaries

  • Show which parser, converter, extractor, or deserializer runs at each step.
  • Record parser-specific decisions driven by extension, MIME, magic bytes, schema, archive member names, or embedded metadata.
  • Distinguish parsing success, preview success, conversion success, and business-logic acceptance.

3. Reduce To The Decisive File Chain

  • Compress the result to the smallest sequence: upload -> derived artifact -> parser boundary -> resulting effect.
  • State clearly whether the decisive weakness lives in archive handling, MIME inference, file conversion, path resolution, or deserialization.
  • If the chain becomes mostly a generic async worker problem after enqueue, hand off to the tighter queue or worker skill.

Read the full file on GitHub · 51 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 51 lines · 109 tokens per session scan A ac09fa9241fd

Subscribe to this mod's changes

competition-file-parser-chain is a skill published in the GitHub repository 2233admin/reverse-skill-evolver (13 stars, last pushed 22d ago), licensed MIT. It adds 109 tokens to every session and 613 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to competition-file-parser-chain, differing in 0 lines, and is treated as a copy.

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