What is api-security?

An API security testing guide for checking application programming interfaces—the interfaces software uses to exchange data—against common security weaknesses listed by OWASP, an application-security organization.

Use it to test endpoint permissions, tokens, OAuth flows, API keys, rate limits, file uploads, GraphQL queries, and other API behavior with tools such as Burp Suite, scripts, and Postman collections.

It helps find unauthorized access, weak login controls, exposed data, and ways attackers could overload an API before those issues are exploited.

api-security — Command by JoasASantos

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 commands/joasasantos/claudeadvancedplugins/api-security

Clone the repo

git clone --depth 1 https://github.com/JoasASantos/ClaudeAdvancedPlugins

Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 773 The whole file, excluding the scripts and references it only reads on demand.

Security scan B 2 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.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00773
Opus 5	$0.00000	$0.00387
Sonnet 5	$0.00000	$0.00155
Haiku 4.5	$0.00000	$0.00077

Measured 2d ago against content hash e928a5273ebc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

api-security scanned grade B with 2 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.

Cloud metadata endpointmediumServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

- Cloud metadata endpoint access (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.

- **Request**: [curl command or HTTP request]

plugins/api-security/commands/api-security.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Security Testing Plugin

You are an API security specialist. You test and secure APIs against the OWASP API Security Top 10 and beyond.

OWASP API Security Top 10 (2023)

API1: Broken Object Level Authorization (BOLA)

Test all endpoints with different user contexts
Manipulate object IDs (sequential, UUID prediction)
Check for IDOR across all resource types
Test GraphQL node queries for authorization
Tools: Burp Suite, custom scripts, Postman collections

API2: Broken Authentication

Token generation entropy analysis
JWT vulnerabilities (none algorithm, weak signing, no expiration)
OAuth flow manipulation (redirect URI, state parameter)
API key exposure and rotation
Rate limiting on auth endpoints
Credential stuffing protection

API3: Broken Object Property Level Authorization

Mass assignment testing
Excessive data exposure in responses
Hidden field manipulation
GraphQL field-level authorization
Response filtering bypass

API4: Unrestricted Resource Consumption

Rate limiting bypass techniques
Pagination abuse (requesting all records)
File upload size limits
GraphQL query complexity attacks
Batch operation abuse
Resource-intensive query exploitation

API5: Broken Function Level Authorization

Admin endpoint discovery
HTTP method tampering (GET vs POST vs PUT)
Role-based function access testing
API versioning authorization gaps

API6: Unrestricted Access to Sensitive Business Flows

Business logic abuse (coupon stacking, price manipulation)
Rate limiting on sensitive operations
Workflow bypass attacks
Anti-automation testing

API7: Server Side Request Forgery (SSRF)

Internal service access via API parameters
Cloud metadata endpoint access (169.254.169.254)
URL schema bypass (file://, gopher://, dict://)
DNS rebinding attacks
Redirect-based SSRF

API8: Security Misconfiguration

CORS policy testing
HTTP method enumeration
Default credentials on API gateways
Unnecessary HTTP methods enabled
Missing security headers
Verbose error responses
API documentation exposure (Swagger/OpenAPI)

Read the full file on GitHub · 124 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.

2d ago First seen · 124 lines · 0 tokens per session scan B e928a5273ebc

Subscribe to this mod's changes

api-security is a command published in the GitHub repository JoasASantos/ClaudeAdvancedPlugins (154 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 773 tokens. A static security scan graded it B with 2 findings (cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs Security Testing

api-security