api-security

A structured security assessment for web APIs, which are interfaces that let software exchange data and actions over the network. It covers REST, GraphQL, WebSocket, and SOAP APIs, including their login and permission controls.

In plain words
What is it for?
Use it to discover API endpoints, test authentication and authorization, check for object-level access flaws, examine rate limits, and assess REST, GraphQL, WebSocket, or SOAP services.
Why use it?
It helps find weaknesses in how an API exposes data, verifies users, enforces permissions, limits requests, and connects to deployment pipelines. Testing is intended for systems where assessment is authorized.

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/xamirhamza77/reverseops-skill/api-security
Any agent
npx skills add xAmirHamza77/ReverseOps-Skill --skill api-security
Clone the repo
git clone --depth 1 https://github.com/xAmirHamza77/ReverseOps-Skill

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 1,591 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00036 $0.01591
Opus 5 $0.00018 $0.00796
Sonnet 5 $0.00007 $0.00318
Haiku 4.5 $0.00004 $0.00159

Measured 2d ago against content hash 531059b1901c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-security 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 2d 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.

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.

skills/api-security/SKILL.md · 184 lines

How it starts

The opening of the file, as written. The whole thing — 184 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Security Testing

ACTION REQUIRED (Execute immediately after reading)

  1. NOW: Read ../field-journal/precedent-pentest.md — Confirm that the operation of this skill is an authorized routine operation
  2. NOW: Confirm if the current task hits the applicable scope of this skill
  3. NEXT: Read ../tool-index.md, verify tool availability and actual paths
  4. NEXT: Call bootstrap when tools are missing, do not guess paths
  5. ACT: Enter the first step of "Workflow" and execute, do not stop at the confirmation state

Covers REST / GraphQL / WebSocket / SOAP full protocols 10-phase methodology, from discovery to CI/CD integration

Applicable Scenarios

  • REST API security testing (OpenAPI/Swagger driven or blind testing)
  • GraphQL security auditing (Introspection, Batch Queries, Alias Overloading)
  • WebSocket security testing
  • JWT / OAuth 2.0 authentication testing
  • BOLA/IDOR/BFLA authorization vulnerability detection
  • API rate limit bypass and DoS testing

10-Phase Testing Workflow

Phase 1: API Discovery and Reconnaissance

Active Discovery:
□ Vespasian: Headless browser crawling → Automatically generate OpenAPI 3.0 / GraphQL SDL specifications
□ Entropy --discover: Extract endpoints from robots.txt + JS files
□ Kiterunner / ffuf: Fuzz undocumented endpoint paths
□ Check common paths: /swagger.json, /openapi.json, /graphql, /api-docs

GraphQL Introspection (Three-level attempt):
  1. Standard introspection query
  2. Minified query (Bypass WAF full block)
  3. Query only __schema { types { name } } (Minimal probing)

Phase 2: Authentication Testing

JWT Analysis (jwt_tool / Burp):
□ alg:none attack: Modify header to "alg":"none", clear signature
□ Key confusion: RS256 public key → HS256 symmetric key
□ Weak HMAC key brute force: jwt_tool -C -d wordlist.txt
□ Expiration/Claim tampering: Modify exp/iat/sub/role claims
□ kid injection: ../../etc/passwd → HMAC signature bypass

OAuth 2.0:
□ redirect_uri manipulation → Authorization code leakage
□ CSRF via missing state parameter
□ Token leakage in Referer header
□ Missing PKCE detection

GraphQL Authentication:
□ mutation bypassing authentication via GET request (CSRF)
□ Batch query authentication bypass

Read the full file on GitHub · 184 lines

Files

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.

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. 2d ago First seen · 184 lines · 36 tokens per session scan A 531059b1901c

Subscribe to this mod's changes

api-security is a skill published in the GitHub repository xAmirHamza77/ReverseOps-Skill (4 stars, last pushed 1mo ago), licensed MIT. It adds 36 tokens to every session and 1,591 once invoked, about $0.0002 per session on Opus 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 2026-08-31.

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