Profile Applicability: Level 2


Description:

Multi-Factor Authentication (MFA) helps to protect your AWS resources. You can enable MFA for IAM users or the AWS account root user. When you enable MFA for the root user, it affects only the root user credentials and does not affect the IAM user, IAM users contain their own credentials means each identity has its own MFA configuration. This Multi-Factor Authentication works as an extra layer of protection on top of a user name and password and we know that the root account is the most privileged user in an AWS account. This extra layer protection enabled, when a user signs in to an AWS website, they will be prompted for their user name and password as well as for an authentication code from their AWS MFA device. For Level 2, it is recommended that the root account be protected with a hardware MFA.

Note: When virtual MFA is used for root accounts, it is recommended that the device used is NOT a personal device, but rather a dedicated mobile device(tablet or phone) that is managed to be kept charged and secured independently of any individual personal devices. (“non-personal virtual MFA”) This lessens the risks of losing access to the MFA due to device loss, device trade-in, or if the individual owning the device is no longer employed at the company.


Rationale:

A hardware MFA has a smaller attack surface than a virtual MFA. e.g., a hardware MFA does not suffer the attack surface introduced by the mobile smartphone on which a virtual MFA resides. It increases security which helps to protect AWS resources, it requires the authenticating principal to possess a device that emits a time-sensitive key and has the knowledge of credentials.

Note: Using hardware MFA for many AWS accounts may create a logistical device management issue. If this is the case, consider implementing this Level 2 recommendation selectively to the highest security AWS accounts and the Level 1 recommendation applied to the remaining accounts.


Impact:

The root account is protected with a Level 2 hardware MFA,  Hardware MFA devices entail additional fees. Hardware MFA devices have fewer potential points of vulnerability than virtual MFA devices and make your root user account more secure.


Default Value:

By default, MFA is not activated for any users if you want to activate MFA for the root user you need to login into the root user account.

 

Pre-Requisite

  1. If you want to activate MFA in the root account you need to log in as a root user.

  2. Before the implementation of the below steps, you need a hardware  MFA device


Remediation:

Test Plan:

Perform the following to determine if the root account has an MFA setup:

  1. Sign in to AWS console as the root user

  2. Click on <user_account_name> top of the right side.

  3. Click on My Security Credential

  4. Check if MFA is activated or not.


Using AWS CLI:

  1. The Account MFA Enabled property is set to 1 will ensure that the 'root' user account has MFA (Virtual or Hardware) Enabled.

  2.  If Account MFA Enabled property is set to 0 the account is not compliant with this recommendation. 

  3.  If Account MFA Enabled property is set to 1, determine 'root' account has Hardware MFA enabled.

  4. Run the following command to list all virtual MFA devices:

    aws iam list-virtual-mfa-devices

  5. If the output contains one MFA with the following Serial Number, it means the MFA is virtual, not hardware and the account is not compliant with this recommendation.

     "SerialNumber": "arn:aws:iam::__:mfa/root-account-mfa-device"

Implementation Plan:

  1. Sign in to the IAM console as the account owner by choosing Root user and entering your AWS account email address. On the next page, enter your password.
  2. On the right side of the navigation bar, choose on your account name, and then choose Security Credentials.  
  3. Expand the Multi-factor authentication (MFA) section and Click on Activate MFA. 

  4. In the wizard, give a name and choose Hardware TOTP token and then choose Continue. 

  5. In the Serial number box, type the serial number that is found on the back of the MFA device. 

  6. In the MFA code 1 box, type the six-digit number displayed by the MFA device. You might need to press      the button on the front of the device to display the number.
  7. Wait 30 seconds while the device refreshes the code, and then type the next six-digit number into the MFA code 2 box. You might need to press the button on the front of the device again to display the second number.
  8. Choose Assign MFA. The MFA device is now associated with the AWS account.

Implementation for this policy is not available through AWS CLI.

Backout Plan:

  • AWS Console Process

  1. Sign in to the IAM console as the account owner by choosing Root user and entering your AWS account email address. On the next page, enter your password.

  2. On the right side of the navigation bar, choose on your account name, and then choose Security Credentials.  

  3. Expand the Multi-factor authentication (MFA) section

  4. In the row for the MFA device select hardware MFA, choose Deactivate.

Backout plan for this policy is not available through AWS CLI.

Reference:

Enabling a hardware TOTP token (console) - AWS Identity and Access Management (amazon.com)

 

CIS Controls:

4.5 Use Multifactor Authentication For All Administrative Access 

  • Use multi-factor authentication and encrypted channels for all administrative account access.