Shopware: Privilege Escalation via Sync API Integration Admin Flag Bypass

Summary

A non-admin API user with integration:create ACL privilege can escalate to full administrator by creating an integration with admin: true through the Sync API (POST /api/_action/sync). The regular integration endpoint (POST /api/integration) correctly blocks this, but the Sync API bypasses the controller-level check by writing directly through the DAL EntityWriter. The integration entity definition lacks WriteProtection, and the admin field has no field-level restriction flag.

OWASP: A01:2021 — Broken Access Control

Root Cause

IntegrationController::upsertIntegration() checks $source->isAdmin() before allowing the admin field to be set. However, SyncController::sync() routes writes through SyncService → EntityWriter, which only applies:

1. AclWriteValidator — checks entity-level ACL (integration:create is sufficient)
2. EntityProtectionValidator — checks WriteProtection on entity definitions, but IntegrationDefinition has none

The admin field in IntegrationDefinition is a plain BoolField with no WriteProtection or special flag. The Sync API writes it without restriction.

Vulnerable code path:

• src/Core/Framework/Api/Controller/SyncController.php → SyncService → EntityWriter::upsert()
• Missing protection: src/Core/Framework/Integration/IntegrationDefinition.php — admin field has no WriteProtection(Context::SYSTEM_SCOPE)

Working protection (bypassed):

• src/Core/Framework/Integration/IntegrationController.php:46-56 — isAdmin() check only applies to the dedicated controller endpoint

Impact

• Complete admin API access — the escalated integration has full read/write on every entity: users, customers, orders, system configuration, integrations, plugins
• PII exfiltration — read all customer records (names, emails, addresses, order history)
• Persistent backdoor — the admin integration survives password changes and user deactivation

Remediation

Add WriteProtection(Context::SYSTEM_SCOPE) to IntegrationDefinition, matching how UserDefinition and AclRoleDefinition are already protected:

// src/Core/Framework/Integration/IntegrationDefinition.php
(new BoolField('admin', 'admin'))
    ->addFlags(new WriteProtection(Context::SYSTEM_SCOPE)),