Which solution will meet these requirements?
Attach a policy to the S3 bucket to prompt the IAM user for an MFA code when the IAM user performs actions on the S3 bucket. Use IAM access keys with the AWS CLI to call Amazon S3.
Update the trust policy for the S3-access group to require principals to use MFA when principals assume the group. Use IAM access keys with the AWS CLI to call Amazon S3.
Attach a policy to the S3-access group to deny all S3 actions unless MFA is present. Use IAM access keys with the AWS CLI to call Amazon S3.
Attach a policy to the S3-access group to deny all S3 actions unless MFA is present. Request temporary credentials from AWS Security Token Service (AWS STS). Attach the temporary credentials in a profile that Amazon S3 will reference when the user performs actions in Amazon S3.
Explanations:
While this option suggests using IAM access keys to call Amazon S3, it does not require the use of MFA for actions performed on the bucket. AWS policies cannot prompt for MFA; they can only enforce its usage through condition keys. Therefore, this option does not meet the requirement for mandatory MFA usage.
This option proposes updating the trust policy for the S3-access group to require MFA, but trust policies are used for roles, not groups. Additionally, IAM groups cannot enforce MFA usage directly; policies need to be attached to the users or roles instead. Hence, this option does not correctly implement MFA requirements for the S3 bucket access.
Although this option attaches a policy to the S3-access group to deny all S3 actions unless MFA is present, it does not provide a mechanism for the cloud engineers to actually use MFA with their IAM access keys to perform actions. This policy alone does not ensure that MFA is enforced during the use of the AWS CLI, as IAM access keys do not inherently support MFA requirements.
This option correctly states to attach a policy to the S3-access group that denies all S3 actions unless MFA is present. It also includes the step to request temporary credentials from AWS STS, which allows the cloud engineers to use MFA effectively. By using temporary credentials, the engineers can authenticate with their MFA devices and perform actions in S3, meeting the requirement for MFA usage.
It appears that the answer is:
Attach a policy to the S3-access group to deny all S3 actions unless MFA is present. Request temporary credentials from AWS Security Token Service (AWS STS). Attach the temporary credentials in a profile that Amazon S3 will reference when the user performs actions in Amazon S3.