Supabase Audit Functions

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:

{"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

Function Discovery Methods

1. Client Code Analysis

// 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": {