MSK clusters should be encrypted in transit among broker nodes¶

This controls checks if an Amazon MSK cluster is encrypted in transit with HTTPS (TLS) among the broker nodes of the cluster. The control fails if plain text communication is enabled for a cluster broker node connection.

How to fix¶

Attribute encryption_info[0].encryption_in_transit[0].in_cluster of aws_msk_cluster must be true.

Implementation options¶

Choose the option that matches how you manage Terraform. All options satisfy this control.

Option 1: Compliance.tf module (recommended)¶

Use the compliance.tf registry module to get this control enforced by default. This control is mapped to the frameworks shown in the tabs above. To begin, see get started with compliance.tf.

module "msk_kafka_cluster" {
  source  = "nistcsf.compliance.tf/terraform-aws-modules/msk-kafka-cluster/aws"
  version = ">=3.0.0"

  broker_node_client_subnets  = ["subnet-abc123", "subnet-def456"]
  broker_node_instance_type   = "kafka.t3.small"
  broker_node_security_groups = ["sg-abc12345"]
  kafka_version               = "3.6.0"
  name                        = "abc123"
  number_of_broker_nodes      = 3
}

Option 2: Open source module (terraform-aws-modules)¶

If you use terraform-aws-modules/msk-kafka-cluster/aws, configure the required module inputs to satisfy this control. You can later migrate to the compliance.tf module with minimal changes because it is compatible by design.

module "msk_kafka_cluster" {
  source  = "terraform-aws-modules/msk-kafka-cluster/aws"
  version = ">=3.0.0"

  broker_node_client_subnets  = ["subnet-abc123", "subnet-def456"]
  broker_node_instance_type   = "kafka.t3.small"
  broker_node_security_groups = ["sg-abc12345"]
  kafka_version               = "3.6.0"
  name                        = "abc123"
  number_of_broker_nodes      = 3

  encryption_in_transit_in_cluster = true
}

Option 3: Terraform AWS provider resources¶

If you manage resources directly, configure the relevant Terraform AWS provider resources to meet this control. See docs for the resources involved: aws_msk_cluster.

resource "aws_msk_cluster" "this" {
  broker_node_group_info {
    client_subnets  = [element(["subnet-abc123", "subnet-def456"], 0)]
    instance_type   = "kafka.m5.large"
    security_groups = ["sg-abc12345"]
  }
  cluster_name           = "pofix-example-cluster"
  kafka_version          = "3.5.1"
  number_of_broker_nodes = 1

  encryption_info {
    encryption_in_transit {
      in_cluster = true
    }
  }
}

Tool mappings¶

Use these identifiers to cross-reference this control across tools, reports, and evidence.

• Compliance.tf (CTF) Control: msk_cluster_encryption_in_transit_with_tls_enabled

• AWS Config Managed Rule: MSK_IN_CLUSTER_NODE_REQUIRE_TLS

• Checkov Check: CKV_AWS_81

• Powerpipe Control: aws_compliance.control.msk_cluster_encryption_in_transit_with_tls_enabled