Description:
Use corporate login credentials instead of personal accounts, such as Gmail accounts.
Rationale:
It is recommended fully-managed corporate Google accounts be used for increased visibility, auditing, and controlling access to Cloud Platform resources. Email accounts based outside of the user's organization, such as personal accounts, should not be used for business purposes.
None.
Follow the documentation and setup corporate login accounts.
Prevention:
To ensure that no email addresses outside the organization can be granted IAM permissions to its Google Cloud projects, folders or organization, turn on the Organization Policy for 'Domain Restricted Sharing'. Learn more at: https://cloud.google.com/resource-manager/docs/organization-policy/restricting-domains.