Information
It is recommended that the principle of 'Separation of Duties' is enforced while assigning KMS related roles to users.
Rationale:
The built-in/predefined IAM role Cloud KMS Admin allows the user/identity to create, delete, and manage service account(s). The built-in/predefined IAM role Cloud KMS CryptoKey Encrypter/Decrypter allows the user/identity (with adequate privileges on concerned resources) to encrypt and decrypt data at rest using an encryption key(s).
The built-in/predefined IAM role Cloud KMS CryptoKey Encrypter allows the user/identity (with adequate privileges on concerned resources) to encrypt data at rest using an encryption key(s). The built-in/predefined IAM role Cloud KMS CryptoKey Decrypter allows the user/identity (with adequate privileges on concerned resources) to decrypt data at rest using an encryption key(s).
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. In Cloud KMS, this could be an action such as using a key to access and decrypt data a user should not normally have access to. 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 best practice.
No user(s) should have Cloud KMS Admin and any of the Cloud KMS CryptoKey Encrypter/Decrypter, Cloud KMS CryptoKey Encrypter, Cloud KMS CryptoKey Decrypter roles assigned at the same time.
Impact:
Removed roles should be assigned to another user based on business needs.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
From Console:
Go to IAM & Admin/IAM using https://console.cloud.google.com/iam-admin/iam
For any member having Cloud KMS Admin and any of the Cloud KMS CryptoKey Encrypter/Decrypter, Cloud KMS CryptoKey Encrypter, Cloud KMS CryptoKey Decrypter roles granted/assigned, click the Delete Bin icon to remove the role from the member.
Note: Removing a role should be done based on the business requirement.