Service accounts should keep the 'Service Account Admin' and 'Service Account User' roles separate

google_service_account

Description

Security best practices recommend that the principle of ‘Separation of Duties’ is enforced while assigning service-account related roles to users. This is achieved by ensuring that no user has the Service Account Admin and Service Account User roles assigned at the same time.

Rationale

The predefined IAM role Service Account admin allows the user/identity to create, delete, and manage service account(s). The predefined IAM role Service Account User allows the user/identity (with adequate privileges on Compute and App Engine) to assign service account(s) to Apps/Compute instances.

Separation of duties is the concept of ensuring that one individual does not have all necessary permissions to be able to complete a malicious action. Using Cloud IAM service accounts, a malicious user could assume the identity of a service account to access resources that they otherwise cannot access.

Separation of duties is a business control typically used in larger organizations, meant to help avoid security or privacy incidents and errors. It is considered a best practice.

No user should have Service Account Admin and Service Account User roles assigned at the same time.

Remediation

  1. Go to IAM & Admin/IAM using https://console.cloud.google.com/iam-admin/iam
  2. For any member having both Service Account Admin and Service Account User roles granted/assigned, click the Delete Bin icon to remove either role from the member.

Removal of a role should be done based on the business requirements.

Impact

The removed role should be assigned to a different user based on business needs.

References

  1. https://cloud.google.com/iam/docs/service-accounts
  2. https://cloud.google.com/iam/docs/understanding-roles
  3. https://cloud.google.com/iam/docs/granting-roles-to-service-accounts

Additional information

Users granted the Owner (roles/owner) and Editor (roles/editor) roles have privileges equivalent to Service Account Admin and Service Account User. To avoid misuse, Owner and Editor roles should be granted to a very limited number of users. Use of these primitive privileges should be minimal. These requirements are addressed in separate recommendations.