supabase-audit-auth-config — Claude Code skill: how to install

---
name: supabase-audit-auth-config
description: Analyze Supabase authentication configuration for security weaknesses and misconfigurations.
---

# Authentication Configuration 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 setting analyzed**
> - Log to `.sb-pentest-audit.log` **BEFORE and AFTER each 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 analyzes the authentication configuration of a Supabase project.

## When to Use This Skill

- To review authentication security settings
- Before production deployment
- When auditing auth-related vulnerabilities
- As part of comprehensive security review

## Prerequisites

- Supabase URL and anon key available
- Detection completed

## Auth Endpoints

Supabase Auth (GoTrue) exposes:

```
https://[project].supabase.co/auth/v1/
```

| Endpoint | Purpose |
|----------|---------|
| `/auth/v1/settings` | Public settings (limited) |
| `/auth/v1/signup` | User registration |
| `/auth/v1/token` | Authentication |
| `/auth/v1/user` | Current user info |
| `/auth/v1/recover` | Password recovery |

## What Can Be Detected

From the public API, we can detect:

| Setting | Detection Method |
|---------|------------------|
| Email auth enabled | Attempt signup |
| Phone auth enabled | Check settings |
| OAuth providers | Check settings |
| Signup disabled | Attempt signup |
| Email confirmation | Signup response |
| Password requirements | Error messages |

## Usage

### Basic Auth Audit

```
Audit authentication configuration
```

### Check Specific Features

```
Check if signup is open and what providers are enabled
```

## Output Format

```
═══════════════════════════════════════════════════════════
 AUTHENTICATION CONFIGURATION AUDIT
═══════════════════════════════════════════════════════════

 Project: abc123def.supabase.co
 Auth Endpoint: https://abc123def.supabase.co/auth/v1/

 ─────────────────────────────────────────────────────────
 Authentication Methods
 ─────────────────────────────────────────────────────────

 Email/Password: ✅ Enabled
 ├── Signup: ✅ Open (anyone can register)
 ├── Email Confirmation: ❌ NOT REQUIRED ← P1 Issue
 ├── Password Min Length: 6 characters ← P2 Consider longer
 └── Secure Password Check: Unknown

 Phone/SMS: ✅ Enabled
 └── Provider: Twilio

 Magic Link: ✅ Enabled
 └── OTP Expiry: 300 seconds (5 min)

 OAuth Providers Detected: 3
 ├── Google: ✅ Enabled
 ├── GitHub: ✅ Enabled
 └── Discord: ✅ Enabled

 Anonymous Auth: ✅ Enabled ← Review if intended

 ─────────────────────────────────────────────────────────
 Security Settings
 ─────────────────────────────────────────────────────────

 Rate Limiting:
 ├── Signup: 3/hour per IP (good)
 ├── Token: 30/hour per IP (good)
 └── Recovery: 3/hour per IP (good)

 Session Configuration:
 ├── JWT Expiry: 3600 seconds (1 hour)
 ├── Refresh Token Rotation: Unknown
 └── Inactivity Timeout: Unknown

 Security Headers:
 ├── CORS: Configured
 ├── Allowed Origins: * (wildcard) ← P2 Consider restricting
 └── Credentials: Allowed

 ─────────────────────────────────────────────────────────
 Findings
 ─────────────────────────────────────────────────────────

 🟠 P1: Email Confirmation Disabled

 Issue: Users can signup and immediately access the app
        without verifying their email address.

 Risks:
 ├── Fake accounts with invalid emails
 ├── Typosquatting ([email protected])
 ├── No verified communication channel
 └── Potential for abuse

 Recommendation:
 Supabase Dashboard → Authentication → Email Templates
 → Enable "Confirm email"

 ─────────────────────────────────────────────────────────

 🟡 P2: Short Minimum Password Length

 Issue: Minimum password length is 6 characters.

 Recommendation: Increase to 8-12 characters minimum.
 Supabase Dashboard → Authentication → Settings
 → Minimum password length

 ─────────────────────────────────────────────────────────

 🟡 P2: Wildcard CORS Origin

 Issue: CORS allows requests from any origin (*).

 Recommendation: Restrict to your domains only.
 Supabase Dashboard → Authentication → URL Configuration
 → Site URL and Redirect URLs

 ─────────────────────────────────────────────────────────

 ℹ️ INFO: Anonymous Auth Enabled

 Note: Anonymous authentication is enabled.

 This is fine if intentional (guest access).
 Review if you expect all users to be authenticated.

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

 Auth Methods: 5 enabled
 OAuth Providers: 3

 Findings:
 ├── P1 (High): 1 - Email confirmation disabled
 ├── P2 (Medium): 2 - Password length, CORS
 └── Info: 1 - Anonymous auth enabled

 Recommended Actions:
 1. Enable email confirmation
 2. Increase minimum password length
 3. Restrict CORS to specific domains
 4. Review if anonymous auth is needed

═══════════════════════════════════════════════════════════
```

## Security Checklist

### Email Authentication

| Setting | Recommended | Risk if Wrong |
|---------|-------------|---------------|
| Email Confirmation | ✅ Required | Fake accounts |
| Password Length | ≥8 chars | Weak passwords |
| Password Complexity | Enable | Easy to guess |
| Rate Limiting | Enable | Brute force |

### OAuth Configuration

| Setting | Recommended | Risk if Wrong |
|---------|-------------|---------------|
| Verified providers only | Yes | Account takeover |
| Proper redirect URLs | Specific URLs | OAuth redirect attacks |
| State parameter | Enabled | CSRF attacks |

### Session Security

| Setting | Recommended | Risk if Wrong |
|---------|-------------|---------------|
| Short JWT expiry | 1 hour or less | Token theft |
| Refresh token rotation | Enabled | Token reuse |
| Secure cookie flags | HttpOnly, Secure, SameSite | XSS, CSRF |

## Context Output

```json
{
  "auth_config": {
    "timestamp": "2025-01-31T12:30:00Z",
    "methods": {
      "email": {
        "enabled": true,
        "signup_open": true,
        "email_confirmation": false,
        "min_password_length": 6
      },
      "phone": {
        "enabled": true,
        "provider": "twilio"
      },
      "magic_link": {
        "enabled": true,
        "otp_expiry": 300
      },
      "oauth": {
        "enabled": true,
        "providers": ["google", "github", "discord"]
      },
      "anonymous": {
        "enabled": true
      }
    },
    "findings": [
      {
        "severity": "P1",
        "issue": "Email confirmation disabled",
        "recommendation": "Enable email confirmation in dashboard"
      }
    ]
  }
}
```

## Common Auth Vulnerabilities

### 1. No Email Confirmation

```javascript
// User can signup with any email
const { data, error } = await supabase.auth.signUp({
  email: '[email protected]',  // No verification needed
  password: 'password123'
})
// User is immediately authenticated
```

### 2. Weak Password Policy

```javascript
// Weak password accepted
await supabase.auth.signUp({
  email: '[email protected]',
  password: '123456'  // Accepted with min length 6
})
```

### 3. Open Signup When Not Needed

If your app should only have admin-created users:

```sql
-- Disable public signup via dashboard
-- Or use invite-only flow
```

## Remediation Examples

### Enable Email Confirmation

1. Supabase Dashboard → Authentication → Email Templates
2. Enable "Confirm email"
3. Customize confirmation email template
4. Handle unconfirmed users in your app

### Strengthen Password Requirements

1. Dashboard → Authentication → Settings
2. Set minimum length to 8+
3. Consider enabling password strength checks

### Restrict CORS

1. Dashboard → Authentication → URL Configuration
2. Set specific Site URL
3. Add only your domains to Redirect URLs
4. Remove wildcard entries

## 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 checking each auth method** → Log the action to `.sb-pentest-audit.log`
2. **After each configuration analyzed** → Immediately update `.sb-pentest-context.json`
3. **After each finding discovered** → Log the severity 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:
   ```json
   {
     "auth_config": {
       "timestamp": "...",
       "methods": { ... },
       "findings": [ ... ]
     }
   }
   ```

2. **Log to `.sb-pentest-audit.log`**:
   ```
   [TIMESTAMP] [supabase-audit-auth-config] [START] Auditing auth configuration
   [TIMESTAMP] [supabase-audit-auth-config] [FINDING] P1: Email confirmation disabled
   [TIMESTAMP] [supabase-audit-auth-config] [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/05-auth-audit/`

### Evidence Files to Create

| File | Content |
|------|---------|
| `auth-settings.json` | Complete auth configuration |

### Evidence Format

```json
{
  "evidence_id": "AUTH-CFG-001",
  "timestamp": "2025-01-31T10:50:00Z",
  "category": "auth-audit",
  "type": "auth_configuration",

  "endpoint": "https://abc123def.supabase.co/auth/v1/",

  "configuration": {
    "email_auth": {
      "enabled": true,
      "signup_open": true,
      "email_confirmation_required": false,
      "min_password_length": 6
    },
    "phone_auth": {
      "enabled": true,
      "provider": "twilio"
    },
    "oauth_providers": ["google", "github", "discord"],
    "anonymous_auth": true
  },

  "security_settings": {
    "rate_limiting": {
      "signup": "3/hour",
      "token": "30/hour",
      "recovery": "3/hour"
    },
    "jwt_expiry": 3600,
    "cors_origins": "*"
  },

  "findings": [
    {
      "severity": "P1",
      "issue": "Email confirmation disabled",
      "impact": "Users can signup without verifying email",
      "recommendation": "Enable email confirmation"
    },
    {
      "severity": "P2",
      "issue": "Weak password policy",
      "impact": "Minimum 6 characters allows weak passwords",
      "recommendation": "Increase to 8+ characters"
    }
  ]
}
```

### Add to curl-commands.sh

```bash
# === AUTH CONFIGURATION TESTS ===
# Test signup availability
curl -X POST "$SUPABASE_URL/auth/v1/signup" \
  -H "apikey: $ANON_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]", "password": "test123456"}'

# Test password policy (weak password)
curl -X POST "$SUPABASE_URL/auth/v1/signup" \
  -H "apikey: $ANON_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]", "password": "123456"}'
```

## Related Skills

- `supabase-audit-auth-signup` — Test signup flow
- `supabase-audit-auth-users` — Test user enumeration
- `supabase-audit-rls` — Auth users need RLS protection