Description

It is recommended to set skip_show_database database flag for Cloud SQL Mysql instance to on

Rationale

skip_show_database database flag prevents people from using the SHOW DATABASES statement if they do not have the SHOW DATABASES privilege. This can improve security if you have concerns about users being able to see databases belonging to other users. Its effect depends on the SHOW DATABASES privilege: If the variable value is ON, the SHOW DATABASES statement is permitted only to users who have the SHOW DATABASES privilege, and the statement displays all database names. If the value is OFF, SHOW DATABASES is permitted to all users, but displays the names of only those databases for which the user has the SHOW DATABASES or other privilege. This recommendation is applicable to Mysql database instances.

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. Ensure the database flag skip_show_database that has been set is listed under the Database flags section.

From Google Cloud CLI

1. List all Cloud SQL database Instances

        gcloud sql instances list

2. Ensure the below command returns on for every Cloud SQL Mysql database instance

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

References

1. https://cloud.google.com/sql/docs/mysql/flags
2. https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_skip_show_database

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/mysql/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 restarts the Cloud SQL instance