# api-security-testing

This skill guides Strix through REST, GraphQL, or gRPC API security tests, then provides a request to reproduce each finding.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 12600 installs · ★ 71969
- Author: usestrix
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/usestrix/strix/tree/HEAD/skills/api-security-testing/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/usestrix-api-security-testing

## What it does

The skill lays out an API-focused test using the OWASP API Security Top 10 (2023) as a checklist. Strix can enumerate endpoints from OpenAPI or Postman specs, GraphQL introspection, or crawling, then test for issues such as BOLA, broken function authorization, SSRF, injection, and token flaws. Findings include a proof-of-concept request.

Prepare a schema, sample object IDs, and credentials with different privileges before a scan. To prove BOLA, the workflow calls for tokens from separate tenants. Pass a gRPC `.proto` file with `--workspace-file`; Strix does not accept it as a target spec. The skill says not to scan an API you do not own. Installing the skill is separate from setting up and running Strix.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add usestrix/strix --skill api-security-testing -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/api-security-testing/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/api-security-testing/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add usestrix/strix --skill api-security-testing -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/api-security-testing/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add usestrix/strix --skill api-security-testing -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/api-security-testing/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install usestrix/strix api-security-testing
```

2. **Manually: put the files in place**
- File: `.github/skills/api-security-testing/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add usestrix/strix --skill api-security-testing -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/usestrix/strix --path skills/api-security-testing
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/api-security-testing/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add usestrix/strix --skill api-security-testing -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/usestrix/strix/tree/HEAD/skills/api-security-testing/SKILL.md

## When to use it
- test an API for BOLA and IDOR
- check function and object-property authorization
- probe an API for SSRF and injection
- reproduce a reported issue with its request
- rerun tests after fixing an authorization flaw

## Example prompts
- Test my API using `./openapi.yaml` and check for BOLA across tenants.
- Check the GraphQL API for field-level authorization flaws and batching abuse.
- Test `https://grpc.staging.example.com` using `./service.proto`.

## Source text · SKILL.md · Apache-2.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 3ca30b59ab040819.

BEGIN THIRD-PARTY FILE 3ca30b59ab040819
```text
---
name: api-security-testing
description: Security-test a REST, GraphQL, or gRPC API with Strix — autonomous agents that enumerate endpoints from an OpenAPI/GraphQL schema (or by crawling), then actually exploit the API-specific vulnerability classes in the OWASP API Security Top 10 (2023) — broken object-level authorization (BOLA/IDOR), broken object property level authorization (excessive data exposure and mass assignment), broken function-level authorization, unrestricted resource consumption, SSRF, injection, and auth/token flaws. Every finding comes with a working proof-of-concept request. Use when the user asks to pentest, security-test, audit, or find vulnerabilities in an API, endpoint, or backend service.
license: Apache-2.0
metadata:
  author: usestrix
  homepage: https://docs.strix.ai
---

# Security-test an API

APIs fail differently from web UIs: there is no rendered surface to crawl, the interesting bugs are authorization-shaped rather than injection-shaped, and the same endpoint behaves differently per token. This workflow targets those specifics with Strix's autonomous agents, using the current [OWASP API Security Top 10 (2023)](https://owasp.org/API-Security/editions/2023/en/0x11-t10/) as the coverage checklist. For the web-app equivalent, the current edition is the OWASP Top 10:2025 — see **owasp-top-10-testing**.

Install, LLM setup, full CLI flags, and the managed-cloud path are in the **penetration-testing-with-strix** skill. Read it if `strix --version` fails or the target is not an API. For a run with no Docker and no LLM key, the same binary drives the managed platform: `strix cloud login`, then `strix cloud scans start ...` (details in **managed-pentesting-with-strix**).

## 1. Gather what the agents need

APIs are near-impossible to test blind, so collect first:

| Input | Why it matters |
|---|---|
| **Schema** — OpenAPI/Swagger file, Postman collection, GraphQL endpoint (introspection), or a gRPC `.proto` | Turns guesswork into full endpoint enumeration. Biggest single win in coverage. An OpenAPI/Swagger or Postman spec (`.json`/`.yaml`/`.yml`) is a target Strix takes directly; a `.proto` is not, so pass it with `--workspace-file`. |
| **Two sets of credentials/tokens**, ideally in different tenants | BOLA/IDOR — API1:2023, still the #1 API risk — can only be *proven* by accessing tenant A's objects with tenant B's token. |
| **A low-privilege and a high-privilege token** | Required to prove broken function-level authorization (API5:2023 — a `user` calling admin-only routes). |
| **Example object IDs** | Lets agents test ID tampering immediately instead of hunting for valid identifiers. |
| **Out-of-scope routes** | Payments, mass notification, destructive admin endpoints. |
| **Rate limits / WAF** in front of the API | Avoids agents burning budget on throttled requests; mention them so testing adapts. |

Ask the user for anything missing — do not fabricate tokens or scan an API they do not own.

## 2. Run the scan
```
END THIRD-PARTY FILE 3ca30b59ab040819

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