Description

It is recommended to set 3625 (trace flag) database flag to off for GCP SQL Server instance.

Rationale

Microsoft SQL trace flags are frequently used to diagnose performance issues or to debug stored procedures or complex computer systems, but they may also be recommended by Microsoft Support to address behavior that is negatively impacting a specific workload. All documented trace flags and those recommended by Microsoft Support are fully supported in a production environment when used as directed. 3625 (trace log) limits the information returned to users who are not members of the sysadmin fixed server role, by masking the parameters of some error messages using ‘******’. Setting this in a Google Cloud flag for the instance allows for security through obscurity and prevents the disclosure of sensitive information. Hence, it is recommended to set this flag to off globally to prevent the flag from being left on or turned on by bad actors. This recommendation is applicable to SQL Server database instances.

Impact

Changing flags on a database may cause it to be restarted. The best time to do this is when there is low usage.

Remediation

From the console

1. Go to the Cloud SQL Instances page in the Google Cloud Console.
2. Select the SQL Server instance for which you want to enable the database flag.
3. Click Edit.
4. Scroll down to the Flags section.
5. Click Add item to set a flag that has not been set on the instance before. Choose the flag 3625 from the drop-down menu, and set its value to off.
6. Click Save.
7. Confirm your changes under the Flags section on the Overview page.

From the command line

Configure the 3625 database flag for every GCP SQL Server database instance using the below command.

gcloud sql instances patch <INSTANCE_NAME> --database-flags "3625=off"

Note

This command will overwrite all database flags previously set. To keep the flags previously set and add new ones, include the values for all flags you want set on the instance; any flag not specifically included is set to its default value. For flags that do not take a value, specify the flag name followed by an equals sign (=).

Additional Information

• Configuring the above flag restarts the GCP SQL Server instance.

• 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.

References

1. https://docs.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql?view=sql-server-ver15#trace-flags