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Ensure that all the requests made during SSL/TLS certificate issue or renewal process are validated. These requests are managed within your account by the Amazon Certificate Manager (ACM), an AWS service that lets you provision, deploy and maintain SSL/TLS certificates for use with other AWS resources such as ELB load balancers, CloudFront distributions or APIs via Amazon API Gateway.

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Risk Level

Medium

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Address

Security

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Compliance Standards

NIST

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Triage and Remediation

  • Cause
  • Remediation

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Check Cause

Using Console

  1. Sign in to the AWS Management Console and open the API Gateway console at 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 ‘Custom Domain Names’. This will display a list of custom domain names associated with the API.
  5. For each custom domain name, check the ‘ACM Certificate’ column. If the certificate is not valid, it will be indicated here.
  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 resources.
  2. Once the AWS CLI is set up, you can list all the API Gateways in your account using the following command: 
    aws apigateway get-rest-apis --region your-region-name
    Replace ‘your-region-name’ with the name of your AWS region. This command will return a list of all the REST APIs in the specified region.
  3. For each API Gateway, you can get the details of the API Gateway’s stages using the following command: 
    aws apigateway get-stages --rest-api-id your-rest-api-id --region your-region-name
    Replace ‘your-rest-api-id’ with the ID of your REST API and ‘your-region-name’ with the name of your AWS region. This command will return a list of all the stages of the specified REST API.
  4. For each stage, check the ‘clientCertificateId’ field. If this field is empty or the certificate ID is not valid, then the ACM Certificate is not valid in the API Gateway. You can check the validity of the certificate ID using the following command: 
    aws acm describe-certificate --certificate-arn your-certificate-arn --region your-region-name
    Replace ‘your-certificate-arn’ with the ARN of your certificate and ‘your-region-name’ with the name of your AWS region. This command will return the details of the specified certificate. If the ‘Status’ field is not ‘ISSUED’, then the certificate is not valid.
  1. Install and configure AWS SDK for Python (Boto3) on your local system. This will allow you to interact with AWS services using Python.
pip install boto3
aws configure
  1. Import the necessary modules and create a session using your AWS credentials.
import boto3
session = boto3.Session(
    aws_access_key_id='YOUR_ACCESS_KEY',
    aws_secret_access_key='YOUR_SECRET_KEY',
    region_name='YOUR_REGION'
)
  1. Use the get_rest_apis method from the apigateway client to get a list of all the APIs in your account. Then, for each API, use the get_domain_names method to get a list of all the domain names associated with that API. For each domain name, check the certificateUploadDate attribute. If it is more than 13 months ago, the certificate is not valid.
client = session.client('apigateway')
apis = client.get_rest_apis()['items']
for api in apis:
    domain_names = client.get_domain_names()['items']
    for domain_name in domain_names:
        if 'certificateUploadDate' in domain_name:
            certificate_age = (datetime.datetime.now(datetime.timezone.utc) - domain_name['certificateUploadDate']).days
            if certificate_age > 395:
                print(f"API Gateway {api['name']} has an invalid certificate for domain {domain_name['domainName']}")
  1. This script will print out the names of all the APIs and their associated domain names that have invalid certificates. You can modify this script to suit your needs, for example by sending an email alert instead of printing to the console.

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Additional Reading:

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