Supabase Audit Buckets Public

Public Bucket Audit

🔴 CRITICAL: PROGRESSIVE FILE UPDATES REQUIRED

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

- Write to .sb-pentest-context.json IMMEDIATELY after each bucket 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

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

This skill specifically focuses on identifying misconfigured public buckets and exposed sensitive content.

When to Use This Skill

• Quick check for public bucket misconfigurations
• When you suspect sensitive data in public storage
• As a focused security check for storage
• Before deploying to production

Prerequisites

• Supabase URL and anon key available

Why Public Buckets Are Risky

Public buckets allow:

Common Misconfiguration Scenarios

1. Development mistake — Bucket set public during development 2. Wrong bucket — Sensitive file uploaded to public bucket 3. Legacy — Bucket was public before RLS existed 4. Intentional but wrong — Assumed "nobody knows the URL"

Usage

Quick Public Bucket Check

Check for misconfigured public buckets

Deep Scan

Deep scan public buckets for sensitive content

Output Format

═══════════════════════════════════════════════════════════
 PUBLIC BUCKET SECURITY AUDIT
═══════════════════════════════════════════════════════════

 Project: abc123def.supabase.co

 ─────────────────────────────────────────────────────────
 Public Bucket Discovery
 ─────────────────────────────────────────────────────────

 Public Buckets Found: 3/5

 ─────────────────────────────────────────────────────────
 1. avatars ✅ APPROPRIATE
 ─────────────────────────────────────────────────────────

 Status: Public (Expected)
 Purpose: User profile pictures
 Content Analysis:
 ├── All files are images (jpg, png, webp)
 ├── No sensitive filenames detected
 ├── File sizes appropriate for avatars (< 1MB)
 └── No metadata concerns

 Assessment: This bucket appropriately contains only
             public user-facing content.

 ─────────────────────────────────────────────────────────
 2. uploads 🟠 P1 - NEEDS REVIEW
 ─────────────────────────────────────────────────────────

 Status: Public (Unexpected for this content)
 Purpose: User file uploads

 Content Analysis:
 ├── Mixed file types (PDF, DOC, images)
 ├── Some sensitive filenames detected
 └── Should likely be private with RLS

 Sensitive Content Indicators:
 ├── 12 files with 'invoice' in name
 ├── 8 files with 'contract' in name
 ├── 3 files with 'passport' in name
 └── 156 PDF files (may contain sensitive data)

 Risk Assessment:
 └── 🟠 User-uploaded content publicly accessible
     Anyone with filename can access any user's files

 Recommendation:

-- Make bucket private UPDATE storage.buckets SET public = false WHERE name = 'uploads';

-- Add user-specific RLS CREATE POLICY "Users access own uploads" ON storage.objects FOR ALL USING ( bucket_id = 'uploads' AND auth.uid()::text = (storage.foldername(name))[1] );

 ─────────────────────────────────────────────────────────
 3. backups 🔴 P0 - CRITICAL MISCONFIGURATION
 ─────────────────────────────────────────────────────────

 Status: Public (SHOULD NEVER BE PUBLIC)
 Purpose: Database backups

 ⚠️ CRITICAL: Backup files publicly accessible!

 Exposed Content:
 ├── 🔴 db-backup-2025-01-30.sql (125MB)
 │   └── Full database dump with all user data
 ├── 🔴 db-backup-2025-01-29.sql (124MB)
 │   └── Previous day backup
 ├── 🔴 users-export.csv (2.3MB)
 │   └── User data export with emails, names
 ├── 🔴 secrets.env (1KB)
 │   └── Contains API keys and passwords!
 └── 🔴 .env.production (1KB)
     └── Production environment secrets!

 Public URLs (Currently Accessible):
 https://abc123def.supabase.co/storage/v1/object/public/backups/db-backup-2025-01-30.sql
 https://abc123def.supabase.co/storage/v1/object/public/backups/secrets.env

 Impact:
 ├── Complete database can be downloaded
 ├── All user PII exposed
 ├── All API secrets exposed
 └── Full application compromise possible

 ═══════════════════════════════════════════════════════════
 🚨 IMMEDIATE ACTION REQUIRED 🚨
 ═══════════════════════════════════════════════════════════

 1. MAKE BUCKET PRIVATE NOW:

UPDATE storage.buckets SET public = false WHERE name = 'backups';

 2. DELETE PUBLIC FILES:
    Delete or move all sensitive files from public access

 3. ROTATE ALL EXPOSED SECRETS:
    - Stripe API keys
    - Database passwords
    - JWT secrets
    - Any other keys in exposed files

 4. AUDIT ACCESS LOGS:
    Check if files were accessed by unauthorized parties

 5. INCIDENT RESPONSE:
    Consider this a data breach and follow your
    incident response procedures

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

 Public Buckets: 3
 ├── ✅ Appropriate: 1 (avatars)
 ├── 🟠 P1 Review: 1 (uploads)
 └── 🔴 P0 Critical: 1 (backups)

 Exposed Sensitive Files: 47
 Exposed Secret Files: 2

 Critical Finding: Database backups and secrets
                   publicly accessible via direct URL

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

Bucket Classification

The skill classifies buckets by content:

Sensitive Content Patterns

P0 - Critical (Never Public)

• *.sql - Database dumps
• *.env* - Environment files
• *secret*, *credential* - Secrets
• *backup* - Backup files
• *export* - Data exports

P1 - High (Usually Private)

• *invoice*, *payment* - Financial
• *contract*, *agreement* - Legal
• *passport*, *id*, *license* - Identity
• User-uploaded documents

P2 - Medium (Review Needed)

• Configuration files
• Log files
• Debug exports

Context Output

{
  "public_bucket_audit": {
    "timestamp": "2025-01-31T12:00:00Z",
    "public_buckets": 3,
    "findings": [
      {
        "bucket": "backups",
        "severity": "P0",
        "issue": "Database backups and secrets publicly accessible",
        "exposed_files": 45,
        "critical_files": [
          "db-backup-2025-01-30.sql",
          "secrets.env",
          ".env.production"
        ],
        "remediation": "Make bucket private immediately, rotate secrets"
      }
    ]
  }
}

Prevention Checklist

After fixing issues, implement these controls:

1. Default Private Buckets

-- Supabase creates buckets public by default in UI
-- Always verify and change to private if needed
UPDATE storage.buckets
SET public = false
WHERE name = 'new-bucket';

2. Restrict Bucket Creation

-- Only allow admin to create buckets
REVOKE INSERT ON storage.buckets FROM authenticated;
REVOKE INSERT ON storage.buckets FROM anon;

3. File Upload Validation

// Validate file type before upload
const allowedTypes = ['image/jpeg', 'image/png'];
if (!allowedTypes.includes(file.type)) {
  throw new Error('Invalid file type');
}

// Use user-specific paths
const path = `${user.id}/${file.name}`;
await supabase.storage.from('uploads').upload(path, file);

4. Regular Audits

Run this skill regularly:

• Before each production deployment
• Weekly automated scans
• After any storage configuration changes

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 analyzing each bucket → Log the action to .sb-pentest-audit.log 2. After each misconfiguration found → Immediately update .sb-pentest-context.json 3. After each sensitive file detected → Log the finding 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:

   {
     "public_bucket_audit": {
       "timestamp": "...",
       "public_buckets": 3,
       "findings": [ ... ]
     }
   }

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

   [TIMESTAMP] [supabase-audit-buckets-public] [START] Auditing public buckets
   [TIMESTAMP] [supabase-audit-buckets-public] [FINDING] P0: backups bucket is public
   [TIMESTAMP] [supabase-audit-buckets-public] [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/04-storage-audit/public-url-tests/

Evidence Files to Create

Evidence Format

{
  "evidence_id": "STG-PUB-001",
  "timestamp": "2025-01-31T10:45:00Z",
  "category": "storage-audit",
  "type": "public_bucket_audit",
  "severity": "P0",

  "bucket": "backups",

  "public_url_test": {
    "url": "https://abc123def.supabase.co/storage/v1/object/public/backups/secrets.env",
    "curl_command": "curl -I 'https://abc123def.supabase.co/storage/v1/object/public/backups/secrets.env'",
    "response_status": 200,
    "content_type": "text/plain",
    "accessible": true
  },

  "assessment": {
    "classification": "critical_misconfiguration",
    "should_be_public": false,
    "contains_sensitive_data": true,
    "file_types_exposed": ["sql", "env", "csv"]
  },

  "remediation": {
    "immediate": "UPDATE storage.buckets SET public = false WHERE name = 'backups';",
    "secrets_to_rotate": ["All keys in secrets.env"],
    "incident_response": "Consider this a data breach"
  }
}

Related Skills

• supabase-audit-buckets-list — List all buckets
• supabase-audit-buckets-read — Test file access
• supabase-report — Generate comprehensive report