supabase-audit-buckets-public

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

Public Bucket 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 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

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:
 ```sql
 -- 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:

| Classification | Criteria | Action |
|----------------|----------|--------|
| **Appropriate Public** | Profile images, public assets | None needed |
| **Needs Review** | User uploads, mixed content | Consider making private |
| **Critical Misconfiguration** | Backups, secrets, exports | Immediate remediation |

## 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

```json
{
  "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