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# Expiring SSL Client Certificates Should Be Rotated

### More Info:

The client-side SSL certificates used by your Amazon API Gateway REST APIs for secure authentication at the API integration endpoint level should be rotated before their expiration date

### Risk Level

Medium

### Address

Security

### Compliance Standards

GDPR

### Triage and Remediation

<Tabs>
  <Tab title="Cause">
    ### Check Cause

    <AccordionGroup>
      <Accordion title="Using Console" defaultOpen="true">
        1. Sign in to the AWS Management Console and open the API Gateway console at [https://console.aws.amazon.com/apigateway/](https://console.aws.amazon.com/apigateway/).

        2. In the navigation pane, choose 'APIs'.

        3. In the APIs pane, choose the API you want to check.

        4. In the API details pane, choose 'Client Certificates'.

        5. In the Client Certificates pane, you can see the expiration date of the SSL client certificate. If the certificate is about to expire, it indicates a misconfiguration.
      </Accordion>

      <Accordion title="Using CLI">
        1. First, you need to install and configure AWS CLI on your local machine. You can do this by following the instructions provided by AWS. Make sure you have the necessary permissions to access the API Gateway.

        2. Once the AWS CLI is installed and configured, you can use the following command to list all the APIs in your AWS account:

           ```
           aws apigateway get-rest-apis
           ```

           This command will return a list of all the APIs in your account. Note down the id of the API you want to check.

        3. Now, you can use the following command to get the details of the API:

           ```
           aws apigateway get-rest-api --rest-api-id <your-api-id>
           ```

           Replace `<your-api-id>` with the id of your API. This command will return the details of the API including the client certificate id if one is associated with the API.

        4. Finally, you can use the following command to get the details of the client certificate:

           ```
           aws apigateway get-client-certificate --client-certificate-id <your-client-certificate-id>
           ```

           Replace `<your-client-certificate-id>` with the id of your client certificate. This command will return the details of the client certificate including the expiration date. You can then check if the certificate is about to expire.
      </Accordion>

      <Accordion title="Using Python">
        1. **Setup AWS SDK (Boto3) in Python:**
           First, you need to set up AWS SDK (Boto3) in your Python environment. You can install it using pip:
           ```
           pip install boto3
           ```
           Then, configure your AWS credentials either by setting up environment variables or by using the AWS CLI.

        2. **List all the API Gateways:**
           Use the `get_rest_apis` function from the `apigateway` client in Boto3 to list all the API Gateways in your AWS account. Here is a sample script:
           ```python theme={null}
           import boto3

           def list_apis():
               client = boto3.client('apigateway')
               response = client.get_rest_apis()
               return response['items']

           apis = list_apis()
           for api in apis:
               print(api['name'], api['id'])
           ```
           This script will print the name and ID of all the API Gateways.

        3. **Get the Client Certificate of each API Gateway:**
           Use the `get_client_certificate` function from the `apigateway` client in Boto3 to get the details of the client certificate of each API Gateway. Here is a sample script:
           ```python theme={null}
           import boto3

           def get_certificate(api_id):
               client = boto3.client('apigateway')
               response = client.get_client_certificate(clientCertificateId=api_id)
               return response

           apis = list_apis()
           for api in apis:
               certificate = get_certificate(api['id'])
               print(certificate)
           ```
           This script will print the details of the client certificate of each API Gateway.

        4. **Check the Expiration Date of the Client Certificate:**
           The `get_client_certificate` function returns a dictionary that includes the `expirationDate` of the client certificate. You can compare this date with the current date to check if the certificate is expiring soon. Here is a sample script:
           ```python theme={null}
           import boto3
           from datetime import datetime, timedelta

           def is_expiring_soon(certificate):
               expiration_date = datetime.fromtimestamp(certificate['expirationDate'])
               return expiration_date < datetime.now() + timedelta(days=30)

           apis = list_apis()
           for api in apis:
               certificate = get_certificate(api['id'])
               if is_expiring_soon(certificate):
                   print(f"The client certificate of the API Gateway {api['name']} is expiring soon.")
           ```
           This script will print a warning message for each API Gateway whose client certificate is expiring in less than 30 days.
      </Accordion>
    </AccordionGroup>
  </Tab>

  <Tab title="Remediation">
    ### Remediation

    <AccordionGroup>
      <Accordion title="Using Console" defaultOpen="true">
        Sure, here are the step-by-step instructions to remediate the issue of expiring SSL client certificates for AWS using the AWS console:

        1. Log in to your AWS Management Console.
        2. Navigate to the AWS Certificate Manager (ACM) service.
        3. Select the certificate that needs to be rotated.
        4. Click on the "Actions" button and select "Renew certificate".
        5. Follow the prompts to generate a new SSL client certificate.
        6. Once the new certificate is generated, update all applications and services to use the new certificate.
        7. Verify that the new certificate is working properly by testing all applications and services that use it.

        That's it! By following these steps, you will have successfully remediated the issue of expiring SSL client certificates in AWS.

        #
      </Accordion>

      <Accordion title="Using CLI">
        To remediate the misconfiguration of expiring SSL client certificates that should be rotated in AWS using AWS CLI, follow the below steps:

        1. Open the AWS CLI on your local machine.

        2. Run the following command to list all the IAM users with expiring SSL client certificates:

        ```
        aws iam list-users --query "Users[].[UserName,UserId,SSHPublicKeys[?SSHPublicKeyId==null]|[?SSHPublicKeyId==''],SSHPublicKeys[?SSHPublicKeyId!=null].[SSHPublicKeyId,Status,UploadDate,UserName]]" --output table
        ```

        This command will list all the IAM users with expiring SSL client certificates.

        3. Identify the IAM user(s) that need to rotate their SSL client certificates.

        4. Run the following command to delete the expiring SSL client certificate(s) for the identified IAM user(s):

        ```
        aws iam delete-ssh-public-key --user-name <IAM user name> --ssh-public-key-id <SSH public key ID>
        ```

        Make sure to replace `<IAM user name>` and `<SSH public key ID>` with the actual values.

        5. Run the following command to upload a new SSL client certificate for the identified IAM user(s):

        ```
        aws iam upload-ssh-public-key --user-name <IAM user name> --ssh-public-key-body <SSH public key>
        ```

        Make sure to replace `<IAM user name>` and `<SSH public key>` with the actual values.

        6. Verify that the new SSL client certificate has been uploaded successfully by running the following command:

        ```
        aws iam list-ssh-public-keys --user-name <IAM user name> --query "SSHPublicKeys[].[SSHPublicKeyId,Status,UploadDate,UserName]" --output table
        ```

        Make sure to replace `<IAM user name>` with the actual value.

        7. Repeat steps 3 to 6 for all the IAM users with expiring SSL client certificates.

        By following the above steps, you can remediate the misconfiguration of expiring SSL client certificates that should be rotated in AWS using AWS CLI.
      </Accordion>

      <Accordion title="Using Python">
        To remediate the issue of expiring SSL client certificates that should be rotated in AWS using Python, you can follow the below steps:

        1. First, you need to identify the SSL client certificates that are going to expire soon. You can use the AWS SDK for Python (Boto3) to get the information about the SSL client certificates. The following code snippet can be used to retrieve the SSL client certificates:

        ```python theme={null}
        import boto3
        from datetime import datetime, timedelta

        client = boto3.client('iam')

        # Get the list of SSL client certificates
        ssl_certs = client.list_server_certificates()['ServerCertificateMetadataList']

        # Get the current date and time
        now = datetime.now()

        # Define the threshold for expiration
        expiration_threshold = timedelta(days=30)

        # Loop through the SSL client certificates and check if they are going to expire soon
        for cert in ssl_certs:
            expiration_date = cert['Expiration']
            if (expiration_date - now) < expiration_threshold:
                print(f"The SSL client certificate {cert['ServerCertificateName']} is going to expire soon.")
        ```

        2. Once you have identified the SSL client certificates that are going to expire soon, you need to rotate them. To rotate the SSL client certificates, you can use the following code snippet:

        ```python theme={null}
        import boto3

        client = boto3.client('iam')

        # Get the list of SSL client certificates
        ssl_certs = client.list_server_certificates()['ServerCertificateMetadataList']

        # Loop through the SSL client certificates and rotate them
        for cert in ssl_certs:
            certificate_name = cert['ServerCertificateName']
            client.rotate_server_certificate(ServerCertificateName=certificate_name)
            print(f"The SSL client certificate {certificate_name} has been rotated.")
        ```

        3. Finally, you can schedule a job to run this Python script periodically to ensure that the SSL client certificates are rotated before they expire. You can use AWS Lambda or any other scheduling service to run the script on a scheduled basis.

        Note: Before running the script, ensure that you have the necessary permissions to access the SSL client certificates in AWS IAM.
      </Accordion>
    </AccordionGroup>
  </Tab>
</Tabs>

### Additional Reading:

* [https://docs.aws.amazon.com/apigateway/latest/developerguide/getting-started-client-side-ssl-authentication.html](https://docs.aws.amazon.com/apigateway/latest/developerguide/getting-started-client-side-ssl-authentication.html)