Ctf Writeup Agent Skill

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:

• Challenge metadata — name, CTF event, category, difficulty, points, flag format
• Solution artifacts — exploit scripts, payloads, screenshots, command output
• 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
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