supabase-audit-functions

Imported from yoanbernabeu/supabase-pentest-skills (skills/audit-functions/supabase-audit-functions/SKILL.md) via skills.sh. Install upstream with npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-functions. Copyright stays with the author.

Edge Functions Audit

🔴 CRITICAL: PROGRESSIVE FILE UPDATES REQUIRED

You MUST write to context files AS YOU GO, not just at the end.

• Write to .sb-pentest-context.json IMMEDIATELY after each function tested
• Log to .sb-pentest-audit.log BEFORE and AFTER each function test
• DO NOT wait until the skill completes to update files
• If the skill crashes or is interrupted, all prior findings must already be saved

This is not optional. Failure to write progressively is a critical error.

This skill discovers and tests Supabase Edge Functions for security issues.

When to Use This Skill

• To discover exposed Edge Functions
• To test function authentication requirements
• To check for input validation issues
• As part of comprehensive security audit

Prerequisites

• Supabase URL available
• Detection completed

Understanding Edge Functions

Supabase Edge Functions are Deno-based serverless functions:

https://[project].supabase.co/functions/v1/[function-name]

Tests Performed

Usage

Basic Function Audit

Audit Edge Functions on my Supabase project

Test Specific Function

Test the process-payment Edge Function for security issues

Output Format

═══════════════════════════════════════════════════════════
 EDGE FUNCTIONS AUDIT
═══════════════════════════════════════════════════════════

 Project: abc123def.supabase.co
 Endpoint: https://abc123def.supabase.co/functions/v1/

 ─────────────────────────────────────────────────────────
 Function Discovery
 ─────────────────────────────────────────────────────────

 Discovery Method: Common name enumeration + client code analysis

 Functions Found: 5

 ─────────────────────────────────────────────────────────
 1. hello-world
 ─────────────────────────────────────────────────────────

 Endpoint: /functions/v1/hello-world
 Method: GET, POST

 Authentication Test:
 ├── Without JWT: ✅ 200 OK
 └── Status: ℹ️ Public function (no auth required)

 Response:
 ```json
 {"message": "Hello, World!"}

Assessment: ✅ APPROPRIATE Simple public endpoint, no sensitive operations.

───────────────────────────────────────────────────────── 2. process-payment ─────────────────────────────────────────────────────────

Endpoint: /functions/v1/process-payment Method: POST

Authentication Test: ├── Without JWT: ❌ 401 Unauthorized ├── With valid JWT: ✅ 200 OK └── Status: ✅ Authentication required

Input Validation Test: ├── Missing amount: ❌ 400 Bad Request (good) ├── Negative amount: ❌ 400 Bad Request (good) ├── String amount: ❌ 400 Bad Request (good) └── Valid input: ✅ 200 OK

Error Response Test: ├── Error format: Generic message (good) └── Stack trace: ❌ Not exposed (good)

Assessment: ✅ PROPERLY SECURED Requires auth, validates input, safe error handling.

───────────────────────────────────────────────────────── 3. get-user-data ─────────────────────────────────────────────────────────

Endpoint: /functions/v1/get-user-data Method: GET

Authentication Test: ├── Without JWT: ❌ 401 Unauthorized └── Status: ✅ Authentication required

Authorization Test: ├── Request own data: ✅ 200 OK ├── Request other user's data: ✅ 200 OK ← 🔴 P0! └── Status: 🔴 BROKEN ACCESS CONTROL

Test:

# As user A, request user B's data
curl https://abc123def.supabase.co/functions/v1/get-user-data?user_id=user-b-id \
  -H "Authorization: Bearer [user-a-token]"

# Returns user B's data!

Finding: 🔴 P0 - IDOR VULNERABILITY Function accepts user_id parameter without verifying that the authenticated user is requesting their own data.

Fix:

// In Edge Function
const { user_id } = await req.json();
const jwt_user = getUser(req); // From JWT

// Verify ownership
if (user_id !== jwt_user.id) {
  return new Response('Forbidden', { status: 403 });
}

───────────────────────────────────────────────────────── 4. admin-panel ─────────────────────────────────────────────────────────

Endpoint: /functions/v1/admin-panel Method: GET, POST

Authentication Test: ├── Without JWT: ❌ 401 Unauthorized ├── With regular user JWT: ✅ 200 OK ← 🔴 P0! └── Status: 🔴 MISSING ROLE CHECK

Finding: 🔴 P0 - PRIVILEGE ESCALATION Admin function accessible to any authenticated user. No role verification in function code.

Fix:

// Verify admin role
const user = getUser(req);
const { data: profile } = await supabase
  .from('profiles')
  .select('is_admin')
  .eq('id', user.id)
  .single();

if (!profile?.is_admin) {
  return new Response('Forbidden', { status: 403 });
}

───────────────────────────────────────────────────────── 5. webhook-handler ─────────────────────────────────────────────────────────

Endpoint: /functions/v1/webhook-handler Method: POST

Authentication Test: ├── Without JWT: ✅ 200 OK (expected for webhooks) └── Status: ℹ️ Public (webhook endpoints are typically public)

Webhook Security Test: ├── Signature validation: ⚠️ Unable to test (need valid signature) └── Rate limiting: Unknown

Error Response Test:

{
  "error": "Invalid signature",
  "expected": "sha256=abc123...",
  "received": "sha256=xyz789..."
}

Finding: 🟠 P1 - INFORMATION DISCLOSURE Error response reveals expected signature format. Could help attacker understand validation mechanism.

Fix:

// Generic error, log details server-side
if (!validSignature) {
  console.error(`Invalid signature: expected ${expected}, got ${received}`);
  return new Response('Unauthorized', { status: 401 });
}

───────────────────────────────────────────────────────── Summary ─────────────────────────────────────────────────────────

Functions Found: 5

Security Assessment: ├── ✅ Secure: 2 (hello-world, process-payment) ├── 🔴 P0: 2 (get-user-data IDOR, admin-panel privilege escalation) └── 🟠 P1: 1 (webhook-handler info disclosure)

Critical Findings:

1. IDOR in get-user-data - any user can access any user's data
2. Missing role check in admin-panel - any user is admin

Priority Actions:

1. Fix get-user-data to verify user owns requested data
2. Add admin role verification to admin-panel
3. Fix webhook-handler error messages

═══════════════════════════════════════════════════════════

## Common Function Vulnerabilities

| Vulnerability | Description | Severity |
|---------------|-------------|----------|
| No auth | Function accessible without JWT | P0-P2 |
| IDOR | User can access other users' data | P0 |
| Missing role check | Regular user accesses admin functions | P0 |
| Input injection | User input not validated | P0-P1 |
| Info disclosure | Errors reveal internal details | P1-P2 |
| CORS misconfigured | Accessible from unintended origins | P1-P2 |

## Function Discovery Methods

### 1. Client Code Analysis

```javascript
// Look for function invocations in client code
supabase.functions.invoke('function-name', {...})
fetch('/functions/v1/function-name', {...})

2. Common Name Enumeration

Tested function names:

• hello-world, hello, test
• process-payment, payment, checkout
• get-user-data, user, profile
• admin, admin-panel, dashboard
• webhook, webhook-handler, stripe-webhook
• send-email, notify, notification

3. Error Response Analysis

404 Not Found → Function doesn't exist
401 Unauthorized → Function exists, needs auth
200 OK → Function exists, accessible

Context Output

{
  "functions_audit": {
    "timestamp": "2025-01-31T14:30:00Z",
    "functions_found": 5,
    "findings": [
      {
        "function": "get-user-data",
        "severity": "P0",
        "vulnerability": "IDOR",
        "description": "Any authenticated user can access any user's data",
        "remediation": "Verify user owns requested resource"
      },
      {
        "function": "admin-panel",
        "severity": "P0",
        "vulnerability": "Privilege Escalation",
        "description": "No role check, any authenticated user is admin",
        "remediation": "Add admin role verification"
      }
    ]
  }
}

Secure Function Patterns

Authentication Check

import { createClient } from '@supabase/supabase-js'

Deno.serve(async (req) => {
  // Get JWT from header
  const authHeader = req.headers.get('Authorization');
  if (!authHeader) {
    return new Response('Unauthorized', { status: 401 });
  }

  // Verify JWT with Supabase
  const supabase = createClient(
    Deno.env.get('SUPABASE_URL')!,
    Deno.env.get('SUPABASE_ANON_KEY')!,
    { global: { headers: { Authorization: authHeader } } }
  );

  const { data: { user }, error } = await supabase.auth.getUser();
  if (error || !user) {
    return new Response('Unauthorized', { status: 401 });
  }

  // User is authenticated
  // ...
});

Authorization Check (IDOR Prevention)

// For user-specific resources
const requestedUserId = body.user_id;
const authenticatedUserId = user.id;

if (requestedUserId !== authenticatedUserId) {
  return new Response('Forbidden', { status: 403 });
}

Role Check (Admin)

// Check admin role
const { data: profile } = await supabase
  .from('profiles')
  .select('role')
  .eq('id', user.id)
  .single();

if (profile?.role !== 'admin') {
  return new Response('Forbidden', { status: 403 });
}

Input Validation

import { z } from 'zod';

const PaymentSchema = z.object({
  amount: z.number().positive().max(10000),
  currency: z.enum(['usd', 'eur', 'gbp']),
  description: z.string().max(200).optional()
});

// Validate input
const result = PaymentSchema.safeParse(body);
if (!result.success) {
  return new Response(
    JSON.stringify({ error: 'Invalid input' }),
    { status: 400 }
  );
}

MANDATORY: Progressive Context File Updates

⚠️ This skill MUST update tracking files PROGRESSIVELY during execution, NOT just at the end.

Critical Rule: Write As You Go

DO NOT batch all writes at the end. Instead:

1. Before testing each function → Log the action to .sb-pentest-audit.log
2. After each vulnerability found → Immediately update .sb-pentest-context.json
3. After each function test completes → Log the result immediately

This ensures that if the skill is interrupted, crashes, or times out, all findings up to that point are preserved.

Required Actions (Progressive)

1. Update .sb-pentest-context.json with results:

   {
     "functions_audit": {
       "timestamp": "...",
       "functions_found": 5,
       "findings": [ ... ]
     }
   }

2. Log to .sb-pentest-audit.log:

   [TIMESTAMP] [supabase-audit-functions] [START] Auditing Edge Functions
   [TIMESTAMP] [supabase-audit-functions] [FINDING] P0: IDOR in get-user-data
   [TIMESTAMP] [supabase-audit-functions] [CONTEXT_UPDATED] .sb-pentest-context.json updated
   

3. If files don't exist, create them before writing.

FAILURE TO UPDATE CONTEXT FILES IS NOT ACCEPTABLE.

MANDATORY: Evidence Collection

📁 Evidence Directory: .sb-pentest-evidence/07-functions-audit/

Evidence Files to Create

Evidence Format (IDOR Vulnerability)

{
  "evidence_id": "FN-001",
  "timestamp": "2025-01-31T11:10:00Z",
  "category": "functions-audit",
  "type": "idor_vulnerability",
  "severity": "P0",

  "function": "get-user-data",
  "endpoint": "https://abc123def.supabase.co/functions/v1/get-user-data",

  "tests": [
    {
      "test_name": "auth_required",
      "request": {
        "method": "GET",
        "headers": {},
        "curl_command": "curl '$URL/functions/v1/get-user-data'"
      },
      "response": {"status": 401},
      "result": "PASS"
    },
    {
      "test_name": "idor_test",
      "description": "As user A, request user B's data",
      "request": {
        "method": "GET",
        "url": "$URL/functions/v1/get-user-data?user_id=user-b-id",
        "headers": {"Authorization": "Bearer [USER_A_TOKEN]"},
        "curl_command": "curl '$URL/functions/v1/get-user-data?user_id=user-b-id' -H 'Authorization: Bearer [USER_A_TOKEN]'"
      },
      "response": {
        "status": 200,
        "body": {"id": "user-b-id", "email": "[REDACTED]", "data": "[REDACTED]"}
      },
      "result": "VULNERABLE",
      "impact": "Any authenticated user can access any other user's data"
    }
  ],

  "remediation": "Add ownership check: if (user_id !== jwt_user.id) return 403"
}

Evidence Format (Privilege Escalation)

{
  "evidence_id": "FN-002",
  "timestamp": "2025-01-31T11:15:00Z",
  "category": "functions-audit",
  "type": "privilege_escalation",
  "severity": "P0",

  "function": "admin-panel",

  "test": {
    "description": "Regular user accessing admin function",
    "request": {
      "method": "GET",
      "headers": {"Authorization": "Bearer [REGULAR_USER_TOKEN]"},
      "curl_command": "curl '$URL/functions/v1/admin-panel' -H 'Authorization: Bearer [REGULAR_USER_TOKEN]'"
    },
    "response": {
      "status": 200,
      "body": {"admin_data": "[REDACTED]"}
    },
    "result": "VULNERABLE",
    "impact": "Any authenticated user has admin access"
  }
}

Related Skills

• supabase-audit-rpc — Database functions (different from Edge Functions)
• supabase-audit-auth-config — Auth configuration
• supabase-report — Include in final report