ctf-writeup
The ctf-writeup skill generates a standardized markdown document that captures a solved CTF challenge in submission format, including challenge metadata, a concise summary, step-by-step solution with working code, and the final flag. Use this after completing a CTF challenge to quickly document the exploit for teammate validation or organizer review during active competition.
git clone --depth 1 https://github.com/ljagiello/ctf-skills /tmp/ctf-writeup && cp -r /tmp/ctf-writeup/ctf-writeup ~/.claude/skills/ctf-writeupSKILL.md
# 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
```bash
# 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
```markdown
---
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
$ARGUMENTSProvides AI and machine learning techniques for CTF challenges. Use when attacking ML models, crafting adversarial examples, performing model extraction, prompt injection, membership inference, training data poisoning, fine-tuning manipulation, neural network analysis, LoRA adapter exploitation, LLM jailbreaking, or solving AI-related puzzles.
Provides cryptography attack techniques for CTF challenges. Use when attacking encryption, hashing, signatures, ZKP, PRNG, or mathematical crypto problems involving RSA, AES, ECC, lattices, LWE, CVP, number theory, Coppersmith, Pollard, Wiener, padding oracle, GCM, key derivation, or stream/block cipher weaknesses.
Provides digital forensics and signal analysis techniques for CTF challenges. Use when analyzing disk images, memory dumps, event logs, network captures, cryptocurrency transactions, steganography, PDF analysis, Windows registry, Volatility, PCAP, Docker images, coredumps, side-channel power traces, DTMF audio spectrograms, packet timing analysis, CD audio disc images, or recovering deleted files and credentials.
Provides malware analysis and network traffic techniques for CTF challenges. Use when analyzing obfuscated scripts, malicious packages, custom crypto protocols, C2 traffic, PE/.NET binaries, RC4/AES encrypted communications, YARA rules, shellcode analysis, memory forensics for malware (Volatility malfind, process injection detection), anti-analysis techniques (VM/sandbox detection, timing evasion, API hashing, process injection, environment checks), or extracting malware configurations and indicators of compromise.
Provides miscellaneous CTF challenge techniques for problems that do not cleanly fit the main categories. Use for encoding puzzles, pyjails, bash jails, RF/SDR, DNS oddities, unicode tricks, esoteric languages, QR or audio puzzles, constraint solving, game theory, unusual sandbox escapes, and hybrid logic puzzles. Prefer a more specific skill first when the challenge is mainly web, pwn, reverse, forensics, malware, OSINT, or crypto. Treat this as the fallback skill for genuine cross-category or edge-case challenges, not the default starting point.
Provides open source intelligence techniques for CTF challenges. Use when gathering information from public sources, social media, geolocation, DNS records, username enumeration, reverse image search, Google dorking, Wayback Machine, Tor relays, FEC filings, or identifying unknown data like hashes and coordinates.
Provides binary exploitation techniques for CTF challenges. Use when you already have a vulnerable native target or service and need to turn memory corruption or low-level primitives into code execution or privilege escalation, such as buffer overflows, format strings, heap bugs, ROP, ret2libc, shellcode, kernel exploitation, seccomp bypass, sandbox escape, or Windows/Linux exploit chains. Do not use it when the main blocker is understanding what the binary does; use reverse engineering first. Do not use it for pure web bugs, disk or packet forensics, or standalone crypto/math challenges.
Provides reverse engineering techniques for CTF challenges. Use when the main job is to understand how a compiled, obfuscated, packed, or virtualized target works before exploiting or solving it, including binaries, APKs, WASM, firmware, custom VMs, bytecode, game clients, malware-like loaders, and anti-debug or anti-analysis logic. Do not use it when the vulnerability is already understood and the remaining task is exploitation; use pwn instead. Do not use it for pure web workflows, log or disk forensics, or standalone crypto problems unless reversing the implementation is the real blocker.