ctf-skills is a collection of agent instructions for solving capture-the-flag security challenges, including web exploitation, binary vulnerabilities, cryptography, reverse engineering, forensics, and OSINT. It is intended for agents and people working through CTF problems, and its skills can be loaded into supported coding-agent workflows.
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.
npx skills add ljagiello/ctf-skills --skill ctf-similar-searchgit clone --depth 1 https://github.com/ljagiello/ctf-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ljagiello/ctf-skills/ctf-similar-search)<a href="https://agentmods.dev/skills/ljagiello/ctf-skills/ctf-similar-search"><img src="https://agentmods.dev/badge/skills/ljagiello/ctf-skills/ctf-similar-search/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ljagiello/ctf-skills/ctf-similar-search"><img src="https://agentmods.dev/badge/skills/ljagiello/ctf-skills/ctf-similar-search.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00059 | $0.01567 |
| Opus 5.5 | $0.00024 | $0.00627 |
| Sonnet 5.5 | $0.00012 | $0.00313 |
| Haiku 4.5 | $0.00006 | $0.00157 |
Grade A, and why
ctf-similar-search 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 yesterday.
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.
How it starts
The opening of the file, as written. The whole thing — 176 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CTF Similar Challenge Search
Search for similar CTF challenge writeups using Tavily API.
Prerequisites
pip install requests tavily
Set your Tavily API key (from https://tavily.com) before running:
export TAVILY_API_KEY='tvly-...'
API Overview
This skill provides two interfaces:
| Interface | Purpose | Command |
|---|---|---|
| Tavily Search | Search for writeups and articles | ./search.sh search <keyword> |
| Tavily Extract | Extract content from URLs | ./search.sh extract <url1> [url2] ... |
Search Workflow
Step 1: Search with Keywords
Choose keywords based on available information:
Scenario 1: Known Competition + Challenge Name
# Format: [Competition Name] [Challenge Name] — max 3 words
./search.sh search "DASCTF URL Storage"
./search.sh search "HGAME baby web"
./search.sh search "BUUCTF pwn1"
Scenario 2: Challenge Name Only (no competition info)
# Use challenge name directly — max 3 words
./search.sh search "URL Storage"
./search.sh search "baby overflow"
./search.sh search "crypto-rsa"
Scenario 3: Unique Identifiers (code snippets, strings)
# Use unique, non-trivial strings from the challenge — NO word limit
./search.sh search "def encrypt_flag(key): return base64"
./search.sh search "CUSTOM_MAGIC_BYTES"
./search.sh search "ERROR: invalid padding in AES block"
⚠️ Critical: 3-Word Limit for Non-Code Queries
All keyword searches that are NOT code snippets or unique identifier strings MUST NOT exceed 3 words. This constraint ensures precise, focused queries that return relevant CTF writeup results instead of broad, diluted searches.
| Search Type | Word Limit | Examples |
|---|---|---|
| Competition + Challenge name | ≤ 3 words | "DASCTF URL Storage", "HGAME baby web" |
| Challenge name only | ≤ 3 words | "URL Storage", "baby overflow" |
| Code snippets / strings | No limit | "def encrypt_flag(key): return base64" |
| Error messages / identifiers | No limit | "CUSTOM_MAGIC_BYTES", "ERROR: invalid padding in AES block" |
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.
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.
- yesterday Changed · +1 lines cfeb99deb4cd
- 8d ago First seen · 175 lines · 59 tokens per session scan A 408c4d219bec
ctf-similar-search is a skill published in the GitHub repository ljagiello/ctf-skills (3,549 stars, last pushed yesterday), licensed MIT. It adds 59 tokens to every session and 1,567 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-20.
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