hacksaws 0.2.0

A command line utility for AWS profiles using dynamic authentication methods such as MFA.

hacksaws

A command line utility for AWS profiles using dynamic authentication methods such as MFA. The CLI allows for dynamic logins to update the credentials for an AWS profile temporarily, while storing the long-term access key and secret in a backup file until the next login or logout call is made. That way dynamic logins can be used while still maintaining the same functional credential interface as non-dynamic credentials.

At this time only MFA-based dynamic logins are supported, but SSO and others will be added in the future.

Usage

To login with MFA, execute the command:

$ hacksaws mfa login <PROFILE_NAME> <MFA_CODE>

There is a --lifespan flag that can be appended here to adjust the amount of time the profile login is valid for before it expires. The default is 12 hours (--lifetime=43200 seconds), but that can be adjusted to a maximum of 24 hours if the profile login allows authentication lifespans of that length.

ECR logins with docker can also be handled with the command by adding the --ecr flag. This will the local docker environment into ECR in the default AWS region for the specified profile.

$ hacksaws mfa login <PROFILE_NAME> <MFA_CODE> --ecr

It is also possible to login to ECR in multiple regions with the --ecr-region flag.

$ hacksaws mfa login <PROFILE_NAME> <MFA_CODE> \
    --ecr \
    --ecr-region=eu-central-1 \
    --ecr-region=us-west-2 \
    --ecr-region=ca-central-1

ECR will always log into the AWS default region. The --ecr-region flag allows for adding additional regions to the login command.

Then to log out:

$ hacksaws mfa logout <PROFILE_NAME>

It is possible to log in and out of ECR for the account with that profile as well by including the --ecr flag in the login call.

Alternate directories for the AWS credentials directory can be specified with the --directory flag.

And for separated AWS credentials directories in the home directory that follow the pattern ~/.aws-<NAME>, a --name flag can be specified to use that directory instead of the default ~/.aws directory. This is a useful pattern for separating profiles by account in cases where one has multiple account credentials.

Requiring MFA

Here's an example policy that allows a user to manage their own user account settings while requiring MFA.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "ViewAccountInfo",
      "Effect": "Allow",
      "Action": [
        "iam:ListUsers",
        "iam:ListAccount*",
        "iam:ListMFADevices",
        "iam:GetAccountPasswordPolicy",
        "iam:GetAccountSummary"
      ],
      "Resource": "*"
    },
    {
      "Sid": "ViewAndManageTheirUser",
      "Effect": "Allow",
      "Action": [
        "iam:*LoginProfile",
        "iam:*AccessKey*",
        "iam:*SSHPublicKey*",
        "iam:*SigningCertificate*",
        "iam:*ServiceSpecificCredential*",
        "iam:GetUser",
        "iam:ChangePassword"
      ],
      "Resource": "arn:aws:iam::*:user/${aws:username}"
    },
    {
      "Sid": "ManageTheirOwnMFA",
      "Effect": "Allow",
      "Action": [
        "iam:CreateVirtualMFADevice",
        "iam:DeactivateMFADevice",
        "iam:DeleteVirtualMFADevice",
        "iam:EnableMFADevice",
        "iam:ListMFADevices",
        "iam:ListVirtualMFADevices",
        "iam:ResyncMFADevice"
      ],
      "Resource": [
        "arn:aws:iam::*:mfa/${aws:username}",
        "arn:aws:iam::*:user/${aws:username}"
      ]
    },
    {
      "Sid": "DenyAllExceptListedIfNoMFA",
      "Effect": "Deny",
      "NotAction": [
        "iam:ListUsers",
        "iam:ListMFADevices",
        "iam:ChangePassword",
        "iam:GetUser",
        "iam:CreateVirtualMFADevice",
        "iam:EnableMFADevice",
        "iam:ListMFADevices",
        "iam:ListVirtualMFADevices",
        "iam:ResyncMFADevice",
        "sts:GetSessionToken"
      ],
      "Resource": "*",
      "Condition": {
        "BoolIfExists": {
          "aws:MultiFactorAuthPresent": "false"
        }
      }
    }
  ]
}

Controlling password quality and expiration policies is an account-level requirement and more details can be found at (Setting an account password policy for IAM users)[https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_passwords_account-policy.html]

Additional Resources:

• Allows MFA-authenticated IAM users...
• IAM: Allows IAM users to self-manage an MFA device
• Configuring MFA-protected API access