MCPInstall

supabase-audit-auth-signup

Test if user signup is open and identify potential abuse vectors in the registration process.

Installs
474
Last 24h
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Trending rank
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Security
Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-signup
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads supabase-audit-auth-signup automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Signup Flow 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 test completed
  • 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 tests the user registration flow for security issues and misconfigurations.

When to Use This Skill

  • To verify if signup is appropriately restricted
  • To test for signup abuse vectors
  • To check rate limiting on registration
  • As part of authentication security audit

Prerequisites

  • Supabase URL and anon key available
  • Auth config audit completed (recommended)

Why Signup Security Matters

Open signup can lead to:

RiskDescription
Spam accountsBots creating fake accounts
Resource abuseFree tier exploitation
Email spamUsing your service to send emails
Data pollutionFake data in your database
Attack surfaceMore accounts = more attack vectors

Tests Performed

TestPurpose
Signup availabilityIs registration open?
Email validationDoes it accept invalid emails?
Rate limitingCan we create many accounts?
Disposable emailsAre temp emails blocked?
Password policyWhat passwords are accepted?
Response informationWhat info is leaked?

Usage

Basic Signup Test

Test signup security on my Supabase project

Check Specific Aspects

Test if disposable emails are blocked for signup

Output Format

═══════════════════════════════════════════════════════════
 SIGNUP FLOW AUDIT
═══════════════════════════════════════════════════════════

 Project: abc123def.supabase.co
 Endpoint: /auth/v1/signup

 ─────────────────────────────────────────────────────────
 Signup Availability
 ─────────────────────────────────────────────────────────

 Status: ✅ OPEN (Anyone can register)

 Test Result:
 POST /auth/v1/signup
 Body: {"email": "test-xxxxx@example.com", "password": "TestPass123!"}
 Response: 200 OK - Account created

 Assessment: Signup is publicly available.
             Review if this is intended.

 ─────────────────────────────────────────────────────────
 Email Validation
 ─────────────────────────────────────────────────────────

 Valid email formats:
 ├── user@domain.com: ✅ Accepted (expected)
 ├── user+tag@domain.com: ✅ Accepted (expected)
 └── user@subdomain.domain.com: ✅ Accepted (expected)

 Invalid email formats:
 ├── user@: ❌ Rejected (good)
 ├── @domain.com: ❌ Rejected (good)
 ├── user@.com: ❌ Rejected (good)
 └── not-an-email: ❌ Rejected (good)

 Disposable Email Test:
 ├── user@mailinator.com: ✅ Accepted ← 🟠 P2
 ├── user@tempmail.com: ✅ Accepted ← 🟠 P2
 └── user@guerrillamail.com: ✅ Accepted ← 🟠 P2

 Finding: Disposable emails are not blocked.
 Risk: Users can create throwaway accounts.

 Recommendation: Consider using an email validation
 service or blocklist in your application logic.

 ─────────────────────────────────────────────────────────
 Password Policy
 ─────────────────────────────────────────────────────────

 Minimum Length Test:
 ├── "12345" (5 chars): ❌ Rejected
 ├── "123456" (6 chars): ✅ Accepted ← P2 Short
 └── "1234567890" (10 chars): ✅ Accepted

 Current Policy: Minimum 6 characters

 Weak Password Test:
 ├── "password": ✅ Accepted ← 🟠 P2
 ├── "123456": ✅ Accepted ← 🟠 P2
 ├── "qwerty123": ✅ Accepted ← 🟠 P2
 └── "letmein": ✅ Accepted ← 🟠 P2

 Finding: Common weak passwords are accepted.

 Recommendation:
 1. Increase minimum length to 8+ characters
 2. Consider password strength requirements
 3. Check against common password lists

 ─────────────────────────────────────────────────────────
 Rate Limiting
 ─────────────────────────────────────────────────────────

 Signup Rate Test (same IP):
 ├── Request 1: ✅ 200 OK
 ├── Request 2: ✅ 200 OK
 ├── Request 3: ✅ 200 OK
 ├── Request 4: ❌ 429 Too Many Requests
 └── Retry-After: 3600 seconds

 Rate Limit: 3 signups/hour per IP
 Assessment: ✅ Rate limiting is active (good)

 ─────────────────────────────────────────────────────────
 Information Disclosure
 ─────────────────────────────────────────────────────────

 Existing Email Test:
 POST /auth/v1/signup (with existing email)
 Response: "User already registered"

 Finding: 🟠 P2 - Response reveals email existence

 This allows:
 ├── Email enumeration attacks
 ├── Knowing if someone has an account
 └── Targeted phishing attempts

 Recommendation: Use generic message like
 "Check your email to continue" for both new
 and existing accounts.

 ─────────────────────────────────────────────────────────
 Email Confirmation
 ─────────────────────────────────────────────────────────

 Status: ❌ NOT REQUIRED (confirmed in auth-config)

 Test: Created account and checked session
 Result: User immediately authenticated without
         email confirmation.

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

 Signup: Open to public
 Rate Limiting: ✅ Active (3/hour)
 Email Confirmation: ❌ Not required

 Findings:
 ├── P1: Email confirmation disabled
 ├── P2: Disposable emails accepted
 ├── P2: Weak passwords accepted
 └── P2: Email enumeration possible

 Security Score: 5/10

 Priority Actions:
 1. Enable email confirmation
 2. Strengthen password policy
 3. Consider disposable email blocking
 4. Use generic error messages

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

Test Details

Disposable Email Detection

Common disposable email domains tested:

  • mailinator.com
  • tempmail.com
  • guerrillamail.com
  • 10minutemail.com
  • throwaway.email

Weak Password List

Common passwords tested:

  • password, password123
  • 123456, 12345678
  • qwerty, qwerty123
  • letmein, welcome
  • admin, administrator

Rate Limit Testing

Attempt 1: 200 OK
Attempt 2: 200 OK
Attempt 3: 200 OK
Attempt 4: 429 Too Many Requests

Context Output

{
  "signup_audit": {
    "timestamp": "2025-01-31T13:00:00Z",
    "signup_open": true,
    "rate_limit": {
      "enabled": true,
      "limit": 3,
      "period": "hour"
    },
    "email_validation": {
      "basic_validation": true,
      "disposable_blocked": false
    },
    "password_policy": {
      "min_length": 6,
      "weak_passwords_blocked": false
    },
    "information_disclosure": {
      "email_enumeration": true
    },
    "findings": [
      {
        "severity": "P1",
        "issue": "Email confirmation disabled"
      },
      {
        "severity": "P2",
        "issue": "Disposable emails accepted"
      },
      {
        "severity": "P2",
        "issue": "Weak passwords accepted"
      },
      {
        "severity": "P2",
        "issue": "Email enumeration possible"
      }
    ]
  }
}

Remediation Examples

Block Disposable Emails

// In your signup handler or Edge Function
import { isDisposable } from 'email-validator-package';

if (isDisposable(email)) {
  throw new Error('Please use a permanent email address');
}

Strengthen Password Requirements

// Custom password validation
function validatePassword(password: string): boolean {
  if (password.length < 8) return false;
  if (!/[A-Z]/.test(password)) return false;
  if (!/[a-z]/.test(password)) return false;
  if (!/[0-9]/.test(password)) return false;
  return true;
}

Prevent Email Enumeration

// Always return same message
async function signup(email, password) {
  try {
    await supabase.auth.signUp({ email, password });
  } catch (error) {
    // Don't reveal if email exists
  }
  return { message: 'Check your email to continue' };
}

Restrict Signup

If signup should be invite-only:

// Use admin API to invite users
const { data, error } = await supabaseAdmin.auth.admin.inviteUserByEmail(
  'user@example.com'
);

// Or disable signup in dashboard and use:
const { data, error } = await supabaseAdmin.auth.admin.createUser({
  email: 'user@example.com',
  email_confirm: true
});

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 each signup test → Log the action to .sb-pentest-audit.log
  2. After each vulnerability found → Immediately update .sb-pentest-context.json
  3. After rate limit tests → Log the results 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:

    {
      "signup_audit": {
        "timestamp": "...",
        "signup_open": true,
        "rate_limit": { ... },
        "findings": [ ... ]
      }
    }
    
  2. Log to .sb-pentest-audit.log:

    [TIMESTAMP] [supabase-audit-auth-signup] [START] Testing signup security
    [TIMESTAMP] [supabase-audit-auth-signup] [FINDING] P2: Weak passwords accepted
    [TIMESTAMP] [supabase-audit-auth-signup] [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/signup-tests/

Evidence Files to Create

FileContent
signup-tests/open-signup.jsonSignup availability test
signup-tests/weak-password.jsonWeak password acceptance test
signup-tests/disposable-email.jsonDisposable email test
signup-tests/rate-limit.jsonRate limiting test

Evidence Format

{
  "evidence_id": "AUTH-SIGNUP-001",
  "timestamp": "2025-01-31T10:55:00Z",
  "category": "auth-audit",
  "type": "signup_test",

  "tests": [
    {
      "test_name": "weak_password_acceptance",
      "severity": "P2",
      "request": {
        "method": "POST",
        "url": "https://abc123def.supabase.co/auth/v1/signup",
        "body": {"email": "test@example.com", "password": "123456"},
        "curl_command": "curl -X POST '$URL/auth/v1/signup' -H 'apikey: $ANON_KEY' -H 'Content-Type: application/json' -d '{\"email\": \"test@example.com\", \"password\": \"123456\"}'"
      },
      "response": {
        "status": 200,
        "message": "User created"
      },
      "result": "VULNERABLE",
      "impact": "Weak passwords (6 chars) accepted"
    },
    {
      "test_name": "disposable_email",
      "severity": "P2",
      "request": {
        "body": {"email": "test@mailinator.com", "password": "Test123456!"}
      },
      "response": {
        "status": 200,
        "message": "User created"
      },
      "result": "VULNERABLE",
      "impact": "Disposable emails not blocked"
    }
  ]
}

Related Skills

  • supabase-audit-auth-config — Full auth configuration
  • supabase-audit-auth-users — User enumeration testing
  • supabase-audit-rls — Protect user data with RLS

FAQ

What does the supabase-audit-auth-signup skill do?

Test if user signup is open and identify potential abuse vectors in the registration process.

How do I install supabase-audit-auth-signup?

Run npx skills add https://github.com/yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-signup in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/supabase-audit-auth-signup/ (personal) or .claude/skills/supabase-audit-auth-signup/ (project).

Which AI agents can use supabase-audit-auth-signup?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is supabase-audit-auth-signup safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains supabase-audit-auth-signup?

It is published by yoanbernabeu in yoanbernabeu/supabase-pentest-skills. It has 474 recorded installs.

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