IAM Policy to Allow Team Wide and User Level Permissions on AWS Secrets Manager

In this post we will simulate a scenario where a team would like to have access to create secrets under a team path name like /security-team/prod/* and /security-team/dev/* and allow all the users from that team to be able to write and read secrets from that path. Then have individual users create and read secrets from their own isolated path: /security-team/personal/aws-username/* so they can create their personal secrets.

Our Scenario:

Create IAM Policy
Create 2 IAM Users: jack.smith and steve.adams
Create IAM Group, Associate IAM Policy to the Group
Attach 2 Users to the Group

The IAM Policy:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Stmt1541597166491",
            "Action": [
                "secretsmanager:CreateSecret",
                "secretsmanager:DeleteSecret",
                "secretsmanager:DescribeSecret",
                "secretsmanager:GetRandomPassword",
                "secretsmanager:GetSecretValue",
                "secretsmanager:ListSecretVersionIds",
                "secretsmanager:ListSecrets",
                "secretsmanager:PutSecretValue",
                "secretsmanager:TagResource",
                "secretsmanager:UpdateSecret"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:secretsmanager:eu-west-1:123456789012:secret:/security-team/prod/*",
                "arn:aws:secretsmanager:eu-west-1:123456789012:secret:/security-team/dev/*",
                "arn:aws:secretsmanager:eu-west-1:123456789012:secret:/security-team/personal/${aws:username}/*"
            ]
        }
    ]
}

Either configure the access keys and secret keys into the credential provider using aws cli, or for this demonstration I will use them inside the code. But never hardcode your credentials.

Create Secrets with Secrets Manager in AWS using Python Boto3

Instantiate user1 and user2:

>>> import boto3
>>> jack = boto3.Session(aws_access_key_id='ya', aws_secret_access_key='xx', region_name='eu-west-1').client('secretsmanager')
>>> steve = boto3.Session(aws_access_key_id='yb', aws_secret_access_key='xx', region_name='eu-west-1').client('secretsmanager')

Create a team wide secret with jack:

>>> jack.create_secret(Name='/security-team/prod/app1/username', SecretString='appreader')
{'ResponseMetadata': {'RetryAttempts': 0, 'HTTPStatusCode': 200, 'RequestId': 'x', 'HTTPHeaders': {'date': 'Thu, 08 Nov 2018 07:50:35 GMT', 'x-amzn-requestid': 'x', 'content-length': '193', 'content-type': 'application/x-amz-json-1.1', 'connection': 'keep-alive'}}, u'VersionId': u'x', u'Name': u'/security-team/prod/app1/username', u'ARN': u'arn:aws:secretsmanager:eu-west-1:123456789012:secret:/security-team/prod/app1/username-12ABC00'}

Let jack and steve try to read the secret:

>>> jack.get_secret_value(SecretId='/security-team/prod/app1/username')['SecretString']
'appreader'
>>> steve.get_secret_value(SecretId='/security-team/prod/app1/username')['SecretString']
'appreader'

Now let jack create a personal secret, let him read it:

>>> jack.create_secret(Name='/security-team/personal/jack.smith/svc1/password', SecretString='secret')
>>> jack.get_secret_value(SecretId='/security-team/personal/jack.smith/svc1/password')['SecretString']
'secret'

Now let steve try to read the secret and you will see that access is denied:

>>> steve.get_secret_value(SecretId='/security-team/personal/jack.smith/username')['SecretString']
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
...
    raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (AccessDeniedException) when calling the GetSecretValue operation: User: arn:aws:iam::123456789012:user/steve.adams is not authorized to perform: secretsmanager:GetSecretValue on resource: arn:aws:secretsmanager:eu-west-1:123456789012:secret:/security-team/personal/jack.smith/svc1/password-a1234b

Thats it for this post

Thank You

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