api-sec

A routing guide for testing the security of APIs, which are interfaces that let software systems communicate. It directs the work toward API discovery, authorization, tokens, or GraphQL and hidden parameters.

In plain words
What is it for?
Use it to plan testing for REST APIs, mobile backends, and GraphQL endpoints, including access control, JWT tokens, undocumented fields, and hidden parameters.
Why use it?
It helps choose the right security-testing path before investigating a specific API weakness.

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/miru-zero/zero-brain/api-sec
Any agent
npx skills add miru-zero/zero-brain --skill api-sec
Clone the repo
git clone --depth 1 https://github.com/miru-zero/zero-brain

Made for: Claude Code, Codex.

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 618 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 95% copy Near-identical to another mod 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 $0.00036 $0.00618
Opus 5 $0.00018 $0.00309
Sonnet 5 $0.00007 $0.00124
Haiku 4.5 $0.00004 $0.00062

Measured yesterday against content hash c713c5d37be0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-sec 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.

Origin

This is a copy

95% identical to api-sec — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/api-sec/SKILL.md · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Security Router

This is the routing entry point for API security testing.

Use this skill first to decide whether the API issue is mostly recon/docs, object authorization, token trust, or GraphQL/hidden parameters, then route to a deeper topic skill.

When to Use

  • The target exposes REST APIs, mobile backends, or GraphQL endpoints
  • You need to define API testing order before going into specific topics
  • You want to handle object authorization, JWT, GraphQL, and hidden fields as separate tracks

Skill Map

Quick Triage

Observation Route
Swagger or OpenAPI is present api-recon-and-docs
IDs appear in URL, JSON, headers, or GraphQL args api-authorization-and-bola
JWT token visible in traffic api-auth-and-jwt-abuse
/graphql or batched JSON arrays are present graphql-and-hidden-parameters
Registration, login, or profile updates accept extra fields api-authorization-and-bola then api-auth-and-jwt-abuse
  1. Start with exposed endpoints and documentation assets
  2. Then evaluate object-level and function-level authorization
  3. Then evaluate token, header, signature, and rate-limit boundaries
  4. If GraphQL or complex JSON is present, continue with hidden fields and schema abuse

Read the full file on GitHub · 47 lines

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. yesterday First seen · 47 lines · 36 tokens per session scan A c713c5d37be0

Subscribe to this mod's changes

api-sec is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 14d ago), licensed MIT. It adds 36 tokens to every session and 618 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to api-sec, differing in 6 lines, and is treated as a copy.

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