CTF Web Solver

CTF Web Solver is a skill for Claude Code, Codex from Spritualkb/CTFskill. It costs 190 tokens per session (5,518 once invoked), scanned C, original, no licence file.

A skill for solving web-based CTF challenges. CTF, or Capture the Flag, is a security competition where participants find vulnerabilities and recover hidden answers.

In plain words
What is it for?
It helps analyze and solve challenges involving SQL injection, XSS, SSRF, SSTI, XXE, file inclusion, command execution, PHP behavior, deserialization, JWTs, Java code, blockchain components, and WAF bypasses.
Why use it?
It guides investigation when a challenge involves web vulnerabilities or application behavior that must be exploited in a controlled competition.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

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/spritualkb/ctfskill/ctf-web-skill
Any agent
npx skills add Spritualkb/CTFskill --skill ctf-web-skill
Clone the repo
git clone --depth 1 https://github.com/Spritualkb/CTFskill

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for CTF Web Solver

README.md
[![agentmods](https://agentmods.dev/badge/skills/spritualkb/ctfskill/ctf-web-skill.svg)](https://agentmods.dev/skills/spritualkb/ctfskill/ctf-web-skill)
Your own site
<a href="https://agentmods.dev/skills/spritualkb/ctfskill/ctf-web-skill"><img src="https://agentmods.dev/badge/skills/spritualkb/ctfskill/ctf-web-skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 190 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,518 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 3 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 5.1 $0.00190 $0.05518
Opus 5 $0.00095 $0.02759
Sonnet 5 $0.00038 $0.01104
Haiku 4.5 $0.00019 $0.00552

Measured 6d ago against content hash 0caff91287b4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade C, and why

CTF Web Solver scanned grade C with 3 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 6d 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.

Encoded or obfuscated payloadmediumSupply chain

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

<script>eval(atob('YWxlcnQoMSk='))</script>

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Cloud metadata endpointmediumServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

4. 云元数据 → 169.254.169.254

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

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

curl -I http://target.com # HTTP 响应头
.agent/skills/ctf-web-skill/SKILL.md · 659 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

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. 6d ago First seen · 659 lines · 190 tokens per session scan C 0caff91287b4

Subscribe to this mod's changes

CTF Web Solver is a skill published in the GitHub repository Spritualkb/CTFskill (5 stars, last pushed 8mo ago), with no licence file. It adds 190 tokens to every session and 5,518 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it C with 3 findings (encoded or obfuscated payload, cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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