ctf-misc

A collection of techniques for capture-the-flag (CTF) security puzzles that do not fit neatly into categories such as web, cryptography, or reverse engineering. CTFs are security competitions built around solving puzzles or finding hidden answers.

In plain words
What is it for?
Use it for encoding puzzles, Python or Bash restricted shells, radio and software-defined-radio tasks, DNS oddities, Unicode tricks, QR codes, audio puzzles, constraint solving, game theory, sandbox escapes, and esoteric languages.
Why use it?
It helps with unusual challenges where standard security categories are not a good match. The listed topics range from encoding and restricted shells to radio, audio, logic, and hybrid puzzles.

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/curiouslearnerdev/online_tools-ai/ctf-misc
Any agent
npx skills add CuriousLearnerDev/Online_Tools-AI --skill ctf-misc
Clone the repo
git clone --depth 1 https://github.com/CuriousLearnerDev/Online_Tools-AI

Made for: Claude Code, Codex.

Per session 122 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 7,196 The whole file, excluding the scripts and references it only reads on demand.
Security scan F 6 findings. Scan, not verified.
Origin unknown No closer match found 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 $0.00122 $0.07196
Opus 5 $0.00061 $0.03598
Sonnet 5 $0.00024 $0.01439
Haiku 4.5 $0.00012 $0.00720

Measured 3d ago against content hash 7c93032c00d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade F, and why

ctf-misc scanned grade F with 6 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 3d 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.

Asks the agent to reveal its instructionsmediumSystem prompt leakage

Directions to print, repeat or translate the system prompt extract configuration the operator did not intend to expose.

- **Emulator ROM-switching:** `/load` replaces ROM but preserves CPU state (registers, RAM, PC). Switch ROMs at specific PCs to combine INIT from one ROM with display instructions from another → read protected memory. Se

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -s -X POST -H "Authorization: Token $CTF_TOKEN" -H "Content-Type: application/json" "$CTF_URL/api/v1/challenges/attempt" -d "{\"challenge_id\": $CID, \"submission\": \"flag{...}\"}"

Harvests environment variableshighData exfiltration

Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.

`COPY (SELECT '') TO PROGRAM 'cmd'` executes OS commands as postgres. `pg_read_file('/path')` reads files. Extract credentials from `pg_basebackup` archives (`global/1260` = `pg_authid`). SSH tunnel to Unix sockets: `ssh

Encoded or obfuscated payloadhighSupply chain

base64 or hex that is decoded and executed hides what actually runs from anyone reading the file.

python3 -c "__import__('os').system('id')"

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

Detect CTFd (`curl -s "$CTF_URL/api/v1/" | head -5`) and interact via API. **Ask the user for their API token** (CTFd Settings > Access Tokens) — it is not provided by default. Then use `Authorization: Token $CTF_TOKEN`

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

`rvim` blocks `:!` but `:python3 import os; os.system("cmd")` executes arbitrary commands. Check `:version` for `+python3`/`+lua`/`+ruby`. See [games-and-vms-3.md](games-and-vms-3.md#rvim-jail-escape-via-custom-vimrc-wit
storage/Skill/ctf-skills/ctf-misc/SKILL.md · 497 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

12 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. 3d ago First seen · 497 lines · 122 tokens per session scan F 7c93032c00d9

Subscribe to this mod's changes

ctf-misc is a skill published in the GitHub repository CuriousLearnerDev/Online_Tools-AI (52 stars, last pushed 1mo ago), with no licence file. It adds 122 tokens to every session and 7,196 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it F with 6 findings (asks the agent to reveal its instructions, sends data to an external url, harvests environment variables). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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