Skills ljagiello ctf-skills ctf-skills

ctf-writeup

Use it when:
You have solved a CTF challenge and want a clean writeup for teammates or organizers.
It does:
Gathers the metadata, artifacts and timeline from the session and fills a submission template.
You get:
A writeup.md file with summary, step-by-step solution, one complete solve script and the flag.
Runs:
When you invoke it by name, after the solve.

Skill 11 of 11 in the ctf-skills bundle, after ctf-misc.

TL;DR

A category skill in the ctf-skills suite that runs after a solve. You invoke it by name; it collects the challenge metadata (name, event, category, difficulty, points, flag format), the exploit scripts and artifacts, and the timeline from the session, then writes a standardized submission-style writeup to writeup.md (or writeup-<name>.md) using a fixed template: summary, numbered solution steps, one complete solve script, and the flag. It optimizes for speed and reproducibility so a teammate or organizer can validate the solve.

Summarizes the skill at 2ad85d3.

npx skills add https://github.com/ljagiello/ctf-skills --skill ctf-writeup
Total Downloads
8,500 on skills.sh, Nov 9, 2026
Repo stars
3,662 ljagiello/ctf-skills
First seen
Mar 27, 2026 on skills.sh
Weekly Downloads
256
-14% over the 8 weeks to Nov 9
Weekly values
Week toInstalls
Sep 21297
Sep 28240
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Oct 26258
Nov 2338
Nov 9256
Category

Compliance, guardrails, skill vetting and browser fingerprinting.

Everything for building software: planning, coding, debugging, design, frameworks, cloud, agents and skills.

Type

A one-shot action you invoke by name, such as turning the conversation into a PRD.

Effect

Its own steps create or change files, git state or local tools.

Needs

Instructions only. Works in any agent that supports skills.

Publisher

Everyone else. Unverified vendor claims default to community.

Topics

SKILL.md

From ljagiello/ctf-skills at 2ad85d3. Checked daily, last changed Nov 6, 2026.

Frontmatter
name: ctf-writeup
description: Generates a single standardized submission-style CTF writeup for competition handoff and organizer review. Use after solving a CTF challenge to document the solution steps, tools used, and lessons learned in a structured format.
license: MIT
compatibility: Requires filesystem-based agent (Claude Code or similar) with bash and Python 3.
allowed-tools: Bash Read Write Edit Glob Grep Task WebFetch WebSearch
metadata:
  user-invocable: "true"
  argument-hint: "[challenge-name]"
  author: Lukasz Jagiello

CTF Write-up Generator

Generate a standardized submission-style CTF writeup for a solved challenge.

Default behavior:

  • During an active competition, optimize for speed, clarity, and reproducibility
  • Keep writeups short enough that a teammate or organizer can validate the solve quickly
  • Always produce a submission-style writeup
  • Prefer one complete solve script from challenge data to final flag

Workflow

Step 1: Gather Information

Collect the following from the current session, challenge files, and user input:

  1. Challenge metadata — name, CTF event, category, difficulty, points, flag format
  2. Solution artifacts — exploit scripts, payloads, screenshots, command output
  3. Timeline — key steps taken, dead ends, pivots
# Scan for exploit scripts and artifacts
find . -name '*.py' -o -name '*.sh' -o -name 'exploit*' -o -name 'solve*' | head -20
# Check for flags in output files
grep -rniE '(flag|ctf|eno|htb|pico)\{' . 2>/dev/null
Step 2: Generate Write-up

Write the writeup file as writeup.md (or writeup-<challenge-name>.md) using the submission template below.


Templates

Submission Format
---
title: "<Challenge Name>"
ctf: "<CTF Event Name>"
date: YYYY-MM-DD
category: web|pwn|crypto|reverse|forensics|osint|malware|misc|ai-ml
difficulty: easy|medium|hard
points: <number>
flag_format: "flag{...}"
author: "<your name or team>"
---

# <Challenge Name>

## Summary

<1-2 sentences: what the challenge was and the core technique. Keep it direct.>

## Solution

### Step 1: <Action>

<Explain the key observation in 3-8 short lines. Keep it direct.>

\`\`\`python
<one complete solving script from provided challenge data to printing the final flag>
\`\`\`

### Step 2: <Action> (optional)

<Only add this when a second short step genuinely helps readability, such as separating the core observation from final verification.>

### Step 3: <Action> (optional)

<Use only if the challenge really needs it. Keep the total number of steps small.>

## Flag

\`\`\`
flag{example_flag_here}
\`\`\`

Guidance:

  • Prefer 1-3 short steps total
  • Keep code to the smallest complete solving script
  • Do not split "recover secret", "derive key", and "decrypt flag" into separate partial snippets
  • The script should start from the challenge data and end by printing the flag
  • Avoid long background sections
  • Avoid dead ends unless they explain a key pivot
  • Avoid multiple alternative solves; pick one clean path
  • Redact the flag only if the user explicitly asks for redaction

Best Practices Checklist

Before finalizing the writeup, verify:

  • [ ] Metadata complete — title, CTF, date, category, difficulty, points, author all filled
  • [ ] Flag handling matches request — keep the real flag unless the user asked for redaction
  • [ ] Reproducible steps — a reader can follow your writeup and reproduce the solution
  • [ ] Code is runnable — exploit scripts include all imports, correct variable names, and comments
  • [ ] No sensitive data — no real credentials, API keys, or private infrastructure details
  • [ ] Length stays concise — the writeup is short enough for fast review
  • [ ] Tools and versions noted — mention specific tool versions if behavior depends on them
  • [ ] Proper attribution — credit teammates, referenced writeups, or tools that were essential
  • [ ] Grammar and formatting — consistent heading levels, code blocks have language tags

Quality Guidelines

DO:

  • Explain just enough for fast verification
  • Include one complete solving path, not multiple alternative routes
  • Include one complete script that goes all the way to the final flag
  • Show actual output (truncated if very long) to prove the approach worked
  • Tag code blocks with language (python, bash, sql, etc.)
  • Keep the main path front-loaded so a reader can validate it quickly

DON'T:

  • Copy-paste raw terminal dumps without explanation
  • Paste several partial snippets that force the reader to reconstruct the final solve
  • Leave placeholder text in the final writeup
  • Include irrelevant tangents that don't contribute to the solution
  • Assume the reader knows the specific challenge setup

Challenge

$ARGUMENTS