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Description

It is recommended not to set contained database authentication database flag for Cloud SQL on the SQL Server instance to on.

Rationale​

A contained database includes all database settings and metadata required to define the database and has no configuration dependencies on the instance of the Database Engine where the database is installed. Users can connect to the database without authenticating a login at the Database Engine level. Isolating the database from the Database Engine makes it possible to easily move the database to another instance of SQL Server. Contained databases have some unique threats that should be understood and mitigated by SQL Server Database Engine administrators. Most of the threats are related to the USER WITH PASSWORD authentication process, which moves the authentication boundary from the Database Engine level to the database level, hence this is recommended not to enable this flag. This recommendation is applicable to SQL Server database instances.

Impact​

When contained database authentication is off (0) for the instance, contained databases cannot be created, or attached to the Database Engine. Turning on logging will increase the required storage over time. Mismanaged logs may cause your storage costs to increase. Setting custom flags via command line on certain instances will cause all omitted flags to be reset to defaults. This may cause you to lose custom flags and could result in unforeseen complications or instance restarts. Because of this, it is recommended you apply these flags changes during a period of low usage.

Audit​

From Google Cloud Console​

  1. Go to the Cloud SQL Instances page in the Google Cloud Console by visiting https://console.cloud.google.com/sql/instances.
  2. Select the instance to open its Instance Overview page
  3. Under the 'Database flags' section, if the database flag contained database authentication is present, then ensure that it is not set to on.

From Google Cloud CLI​

  1. Ensure the below command doesn't return on for any Cloud SQL for SQL Server database instance.

         gcloud sql instances describe <INSTANCE_NAME> --format=json | jq '.settings.databaseFlags[] | select(.name=="contained database authentication")|.value'

References​

  1. https://cloud.google.com/sql/docs/sqlserver/flags
  2. https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/contained-database-authentication-server-configuration-option?view=sql-server-ver15
  3. https://docs.microsoft.com/en-us/sql/relational-databases/databases/security-best-practices-with-contained-databases?view=sql-server-ver15

Additional Information​

WARNING: This patch modifies database flag values, which may require your instance to be restarted. Check the list of supported flags - https://cloud.google.com/sql/docs/sqlserver/flags - to see if your instance will be restarted when this patch is submitted.

Note: Some database flag settings can affect instance availability or stability, and remove the instance from the Cloud SQL SLA. For information about these flags, see Operational Guidelines.

Note: Configuring the above flag does not restart the Cloud SQL instance.