---
description: Security audit your APIs against OWASP API Top 10. Finds vulnerabilities and provides remediation guidance.
allowed-tools: Read, Glob, Grep, mcp__postman__*
---

# API Security Audit

Audit your API for security issues: missing auth, exposed sensitive data, insecure transport, weak validation, and OWASP API Security Top 10 alignment. Works with local OpenAPI specs and Postman collections.

## Prerequisites

For collection auditing, the Postman MCP Server must be connected. Local spec auditing works without MCP. If needed, tell the user: "Run `/postman:setup` to configure the Postman MCP Server."

## Workflow

### Step 1: Find the Source

Call `getWorkspaces` to get the user's workspace ID. If multiple workspaces exist, ask which to use.

**Local spec:**
- Search for `**/openapi.{json,yaml,yml}`, `**/swagger.{json,yaml,yml}`

**Postman spec (via MCP):**
- Call `getAllSpecs` with the workspace ID to find specs
- Call `getSpecDefinition` for the full spec content

**Postman collection (via MCP):**
- Call `getCollections` with the `workspace` parameter
- Call `getCollection` for full detail including auth config
- Call `getEnvironment` to check for exposed secrets

### Step 2: Run Security Checks

**Authentication and Authorization:**
- Security schemes defined (OAuth2, API Key, Bearer, etc.)
- Security applied globally or per-endpoint
- No endpoints accidentally unprotected
- OAuth2 scopes defined and appropriate
- Admin endpoints have elevated auth requirements

**Transport Security:**
- All server URLs use HTTPS
- No mixed HTTP/HTTPS

**Sensitive Data Exposure:**
- No API keys, tokens, or passwords in example values
- No secrets in query parameters (should be headers/body)
- Password fields marked as `format: password`
- PII fields identified
- Postman environment variables checked for leaked secrets (via `getEnvironment`)

**Input Validation:**
- All parameters have defined types
- String parameters have `maxLength`
- Numeric parameters have `minimum`/`maximum`
- Array parameters have `maxItems`
- Enum values used where applicable
- Request body has required field validation

**Rate Limiting:**
- Rate limits documented
- Rate limit headers defined (X-RateLimit-Limit, X-RateLimit-Remaining)
- 429 Too Many Requests response defined

**Error Handling:**
- Error responses don't leak stack traces
- Error schemas don't expose internal field names
- 401 and 403 responses properly defined
- Error messages don't reveal implementation details

**OWASP API Top 10 Alignment:**
- API1: Broken Object Level Authorization
- API2: Broken Authentication
- API3: Broken Object Property Level Authorization
- API4: Unrestricted Resource Consumption
- API5: Broken Function Level Authorization
- API6: Unrestricted Access to Sensitive Business Flows
- API7: Server Side Request Forgery
- API8: Security Misconfiguration
- API9: Improper Inventory Management
- API10: Unsafe Consumption of APIs

### Step 3: Present Results

```
API Security Audit: pet-store-api.yaml

  CRITICAL (2):
    SEC-001: 3 endpoints have no security scheme applied
      - GET /admin/users
      - DELETE /admin/users/{id}
      - PUT /admin/config
    SEC-002: Server URL uses HTTP (http://api.example.com)

  HIGH (3):
    SEC-003: No rate limiting documentation or 429 response
    SEC-004: API key sent as query parameter (use header instead)
    SEC-005: No maxLength on 8 string inputs (injection risk)

  MEDIUM (2):
    SEC-006: Password field visible in GET /users/{id} response
    SEC-007: Environment variable 'db_password' not marked secret

  Score: 48/100 — Significant Issues
```

### Step 4: Fix

For each finding:
1. Explain the security risk in plain terms
2. Show the exact spec change needed
3. Apply the fix with user approval

For Postman-specific issues:
- Call `putEnvironment` to mark secrets properly
- Call `updateCollectionRequest` to fix auth configuration
- Call `updateCollectionResponse` to remove sensitive data from examples

### Step 5: Re-audit

After fixes, re-run the audit to show improvement.

## Error Handling

- **MCP not configured:** Local spec auditing works without MCP. For Postman-specific checks: "Run `/postman:setup` to configure the Postman MCP Server."
- **401 Unauthorized:** "Your Postman API key was rejected. Generate a new one at https://go.postman.co/settings/me/api-keys and run `/postman:setup`."
- **No spec found:** Ask the user for the path. Offer to audit a Postman collection directly via MCP.
- **Spec too large:** For large specs (100+ endpoints), audit in batches by tag or path prefix.
- **Plan limitations:** "Some audit features may require a paid Postman plan. Check https://www.postman.com/pricing/"