Continuous runtime security monitoring with AWS Security Hub and Falco

Customers want a single and comprehensive view of the security posture of their workloads. Runtime security event monitoring is important to building secure, operationally excellent, and reliable workloads, especially in environments that run containers and container orchestration platforms. In this blog post, we show you how to use services such as AWS Security Hub and Falco, a Cloud Native Computing Foundation project, to build a continuous runtime security monitoring solution.

With the solution in place, you can collect runtime security findings from multiple AWS accounts running one or more workloads on AWS container orchestration platforms, such as Amazon Elastic Kubernetes Service (Amazon EKS) or Amazon Elastic Container Service (Amazon ECS). The solution collates the findings across those accounts into a designated account where you can view the security posture across accounts and workloads.

Solution overview

Security Hub collects security findings from other AWS services using a standardized AWS Security Findings Format (ASFF). Falco provides the ability to detect security events at runtime for containers. Partner integrations like Falco are also available on Security Hub and use ASFF. Security Hub provides a custom integrations feature using ASFF to enable collection and aggregation of findings that are generated by custom security products.

The solution in this blog post uses AWS FireLens, Amazon CloudWatch Logs, and AWS Lambda to enrich logs from Falco and populate Security Hub.

Figure : Architecture diagram of continuous runtime security monitoring

Figure 1: Architecture diagram of continuous runtime security monitoring

Here’s how the solution works, as shown in Figure 1:

  1. An AWS account is running a workload on Amazon EKS.
    1. Runtime security events detected by Falco for that workload are sent to CloudWatch logs using AWS FireLens.
    2. CloudWatch logs act as the source for FireLens and a trigger for the Lambda function in the next step.
    3. The Lambda function transforms the logs into the ASFF. These findings can now be imported into Security Hub.
    4. The Security Hub instance that is running in the same account as the workload running on Amazon EKS stores and processes the findings provided by Lambda and provides the security posture to users of the account. This instance also acts as a member account for Security Hub.
  2. Another AWS account is running a workload on Amazon ECS.
    1. Runtime security events detected by Falco for that workload are sent to CloudWatch logs using AWS FireLens.
    2. CloudWatch logs acts as the source for FireLens and a trigger for the Lambda function in the next step.
    3. The Lambda function transforms the logs into the ASFF. These findings can now be imported into Security Hub.
    4. The Security Hub instance that is running in the same account as the workload running on Amazon ECS stores and processes the findings provided by Lambda and provides the security posture to users of the account. This instance also acts as another member account for Security Hub.
  3. The designated Security Hub administrator account combines the findings generated by the two member accounts, and then provides a comprehensive view of security alerts and security posture across AWS accounts. If your workloads span multiple regions, Security Hub supports aggregating findings across Regions.

Prerequisites

For this walkthrough, you should have the following in place:

  1. Three AWS accounts.

    Note: We recommend three accounts so you can experience Security Hub’s support for a multi-account setup. However, you can use a single AWS account instead to host the Amazon ECS and Amazon EKS workloads, and send findings to Security Hub in the same account. If you are using a single account, skip the following account specific-guidance. If you are integrated with AWS Organizations, the designated Security Hub administrator account will automatically have access to the member accounts.

  2. Security Hub set up with an administrator account on one account.
  3. Security Hub set up with member accounts on two accounts: one account to host the Amazon EKS workload, and one account to host the Amazon ECS workload.
  4. Falco set up on the Amazon EKS and Amazon ECS clusters, with logs routed to CloudWatch Logs using FireLens. For instructions on how to do this, see:

    Important: Take note of the names of the CloudWatch Logs groups, as you will need them in the next section.

  5. AWS Cloud Development Kit (CDK) installed on the member accounts to deploy the solution that provides the custom integration between Falco and Security Hub.

Deploying the solution

In this section, you will learn how to deploy the solution and enable the CloudWatch Logs group. Enabling the CloudWatch Logs group is the trigger for running the Lambda function in both member accounts.

To deploy this solution in your own account

  1. Clone the aws-securityhub-falco-ecs-eks-integration GitHub repository by running the following command.
    $git clone https://github.com/aws-samples/aws-securityhub-falco-ecs-eks-integration
  2. Follow the instructions in the README file provided on GitHub to build and deploy the solution. Make sure that you deploy the solution to the accounts hosting the Amazon EKS and Amazon ECS clusters.
  3. Navigate to the AWS Lambda console and confirm that you see the newly created Lambda function. You will use this function in the next section.
Figure : Lambda function for Falco integration with Security Hub

Figure 2: Lambda function for Falco integration with Security Hub

To enable the CloudWatch Logs group

  1. In the AWS Management Console, select the Lambda function shown in Figure 2—AwsSecurityhubFalcoEcsEksln-lambdafunction—and then, on the Function overview screen, select + Add trigger.
  2. On the Add trigger screen, provide the following information and then select Add, as shown in Figure 3.
    • Trigger configuration – From the drop-down, select CloudWatch logs.
    • Log group – Choose the Log group you noted in Step 4 of the Prerequisites. In our setup, the log group for the Amazon ECS and Amazon EKS clusters, deployed in separate AWS accounts, was set with the same value (falco).
    • Filter name – Provide a name for the filter. In our example, we used the name falco.
    • Filter pattern – optional – Leave this field blank.
    Figure 3: Lambda function trigger - CloudWatch Log group

    Figure 3: Lambda function trigger – CloudWatch Log group

  3. Repeat these steps (as applicable) to set up the trigger for the Lambda function deployed in other accounts.

Testing the deployment

Now that you’ve deployed the solution, you will verify that it’s working.

With the default rules, Falco generates alerts for activities such as:

  • An attempt to write to a file below the /etc folder. The /etc folder contains important system configuration files.
  • An attempt to open a sensitive file (such as ) for reading.

To test your deployment, you will attempt to perform these activities to generate Falco alerts that are reported as Security Hub findings in the same account. Then you will review the findings.

To test the deployment in member account 1

  1. Run the following commands to trigger an alert in member account 1, which is running an Amazon EKS cluster. Replace <container_name> with your own value.
    kubectl exec -it <container_name> /bin/bash
    touch /etc/5
    cat /etc/shadow > /dev/null
  2. To see the list of findings, log in to your Security Hub admin account and navigate to Security Hub > Findings. As shown in Figure 4, you will see the alerts generated by Falco, including the Falco-generated title, and the instance where the alert was triggered.
    Figure 4: Findings in Security Hub

    Figure 4: Findings in Security Hub

  3. To see more detail about a finding, check the box next to the finding. Figure 5 shows some of the details for the finding Read sensitive file untrusted.
    Figure 5: Sensitive file read finding - detail view

    Figure 5: Sensitive file read finding – detail view

    Figure 6 shows the Resources section of this finding, that includes the instance ID of the Amazon EKS cluster node. In our example this is the Amazon Elastic Compute Cloud (Amazon EC2) instance.

    Figure 6: Resource Detail in Security Hub finding

To test the deployment in member account 2

  1. Run the following commands to trigger a Falco alert in member account 2, which is running an Amazon ECS cluster. Replace <<container_id> with your own value.
    docker exec -it <container_id> bash
    touch /etc/5
    cat /etc/shadow > /dev/null
  2. As in the preceding example with member account 1, to view the findings related to this alert, navigate to your Security Hub admin account and select Findings.

To view the collated findings from both member accounts in Security Hub

  1. In the designated Security Hub administrator account, navigate to Security Hub > Findings. The findings from both member accounts are collated in the designated Security Hub administrator account. You can use this centralized account to view the security posture across accounts and workloads. Figure 7 shows two findings, one from each member account, viewable in the Single Pane of Glass administrator account.
    Figure 7: Write below /etc findings in a single view

    Figure 7: Write below /etc findings in a single view

  2. To see more information and a link to the corresponding member account where the finding was generated, check the box next to the finding. Figure 8 shows the account detail associated with a specific finding in member account 1.
    Figure 8: Write under /etc detail view in Security Hub admin account

    Figure 8: Write under /etc detail view in Security Hub admin account

    By centralizing and enriching the findings from Falco, you can take action more quickly or perform automated remediation on the impacted resources.

Cleaning up

To clean up this demo:

  1. Delete the CloudWatch Logs trigger from the Lambda functions that were created in the section To enable the CloudWatch Logs group.
  2. Delete the Lambda functions by deleting the CloudFormation stack, created in the section To deploy this solution in your own account.
  3. Delete the Amazon EKS and Amazon ECS clusters created as part of the Prerequisites.

Conclusion

In this post, you learned how to achieve multi-account continuous runtime security monitoring for container-based workloads running on Amazon EKS and Amazon ECS. This is achieved by creating a custom integration between Falco and Security Hub.

You can extend this solution in a number of ways. For example:

  • You can forward findings across accounts using a single source to security information and event management (SIEM) tools such as Splunk.
  • You can perform automated remediation activities based on the findings generated, using Lambda.

To learn more about managing a centralized Security Hub administrator account, see Managing administrator and member accounts. To learn more about working with ASFF, see AWS Security Finding Format (ASFF) in the documentation. To learn more about the Falco engine and rule structure, see the Falco documentation.

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Rajarshi Das

Rajarshi Das

Rajarshi is a Solutions Architect at Amazon Web Services. He focuses on helping Public Sector customers accelerate their security and compliance certifications and authorizations by architecting secure and scalable solutions. Rajarshi holds 4 AWS certifications including AWS Certified Solutions Architect – Professional and AWS Certified Security – Specialist.

Author

Adam Cerini

Adam is a Senior Solutions Architect with Amazon Web Services. He focuses on helping Public Sector customers architect scalable, secure, and cost effective systems. Adam holds 5 AWS certifications including AWS Certified Solutions Architect – Professional and AWS Certified Security – Specialist.