For AI agents: A markdown version of this page is available at https://docs.datadoghq.com/security/code_security/iac_security/iac_rules/cloudformation-aws-cmk-is-unusable.md. A documentation index is available at /llms.txt.

CMK is unusable

This product is not supported for your selected Datadog site. ().

Metadata

Id: cloudformation-aws-cmk-is-unusable

Provider: AWS

Platform: CloudFormation

Severity: Medium

Category: Availability

Learn More

Description

AWS KMS Customer Master Keys (CMKs) used by your stack must be usable so encrypted data can be decrypted and cryptographic operations succeed. Disabled keys or keys scheduled for deletion can lead to decryption failures, service outages, or permanent data loss.

In CloudFormation, AWS::KMS::Key resources must have Properties.Enabled set to true and must not define the Properties.PendingWindowInDays property. Resources missing Enabled or with Enabled set to false will be flagged as unusable. Any resource that defines PendingWindowInDays will be flagged because that indicates the key is scheduled for deletion.

Secure example (enable the key and omit pending-deletion settings):

MyKey:
  Type: AWS::KMS::Key
  Properties:
    Enabled: true

Compliant Code Examples

#this code is a correct code for which the query should not find any result
Resources:
  myKey:
    Type: AWS::KMS::Key
    Properties:
      Enabled: true
      KeyPolicy:
        Version: '2012-10-17'
        Id: key-default-1
        Statement:
        - Sid: Enable IAM User Permissions
          Effect: Allow
          Principal:
            AWS:
              Fn::Join:
              - ''
              - - 'arn:aws:iam::'
                - Ref: AWS::AccountId
                - :root
          Action: kms:*
          Resource: '*'
      Tags:
      - Key:
          Ref: Key
        Value:
          Ref: Value
Parameters:
  Key:
    Type: String
  Value:
    Type: String

{
  "Resources": {
    "myKey": {
      "Type": "AWS::KMS::Key",
      "Properties": {
        "Enabled": true,
        "KeyPolicy": {
          "Version": "2012-10-17",
          "Id": "key-default-1",
          "Statement": [
            {
              "Sid": "Enable IAM User Permissions",
              "Effect": "Allow",
              "Principal": {
                "AWS": {
                  "Fn::Join": [
                    "",
                    [
                      "arn:aws:iam::",
                      {
                        "Ref": "AWS::AccountId"
                      },
                      ":root"
                    ]
                  ]
                }
              },
              "Action": "kms:*",
              "Resource": "*"
            }
          ]
        },
        "Tags": [
          {
            "Key": {
              "Ref": "Key"
            },
            "Value": {
              "Ref": "Value"
            }
          }
        ]
      }
    }
  },
  "Parameters": {
    "Key": {
      "Type": "String"
    },
    "Value": {
      "Type": "String"
    }
  }
}

Non-Compliant Code Examples

#this is a problematic code where the query should report a result(s)
Resources:
  myKey:
    Type: AWS::KMS::Key
    Properties:
      Enabled: false
      KeyPolicy:
        Version: '2012-10-17'
        Id: key-default-1
        Statement:
        - Sid: Enable IAM User Permissions
          Effect: Allow
          Principal:
            AWS:
              Fn::Join:
              - ''
              - - 'arn:aws:iam::'
                - Ref: AWS::AccountId
                - :root
          Action: kms:*
          Resource: '*'
      Tags:
      - Key:
          Ref: Key
        Value:
          Ref: Value
  myKey2:
    Type: AWS::KMS::Key
    Properties:
      Enabled: true
      PendingWindowInDays: 7
      KeyPolicy:
        Version: '2012-10-17'
        Id: key-default-1
        Statement:
        - Sid: Enable IAM User Permissions
          Effect: Allow
          Principal:
            AWS:
              Fn::Join:
              - ''
              - - 'arn:aws:iam::'
                - Ref: AWS::AccountId
                - :root
          Action: kms:*
          Resource: '*'
      Tags:
      - Key:
          Ref: Key
        Value:
          Ref: Value
Parameters:
  Key:
    Type: String
  Value:
    Type: String

{
  "Resources": {
    "myKey": {
      "Type": "AWS::KMS::Key",
      "Properties": {
        "Enabled": false,
        "KeyPolicy": {
          "Id": "key-default-1",
          "Statement": [
            {
              "Resource": "*",
              "Sid": "Enable IAM User Permissions",
              "Effect": "Allow",
              "Principal": {
                "AWS": {
                  "Fn::Join": [
                    "",
                    [
                      "arn:aws:iam::",
                      {
                        "Ref": "AWS::AccountId"
                      },
                      ":root"
                    ]
                  ]
                }
              },
              "Action": "kms:*"
            }
          ],
          "Version": "2012-10-17"
        },
        "Tags": [
          {
            "Key": {
              "Ref": "Key"
            },
            "Value": {
              "Ref": "Value"
            }
          }
        ]
      }
    },
    "myKey2": {
      "Type": "AWS::KMS::Key",
      "Properties": {
        "Tags": [
          {
            "Key": {
              "Ref": "Key"
            },
            "Value": {
              "Ref": "Value"
            }
          }
        ],
        "Enabled": true,
        "PendingWindowInDays": 7,
        "KeyPolicy": {
          "Version": "2012-10-17",
          "Id": "key-default-1",
          "Statement": [
            {
              "Sid": "Enable IAM User Permissions",
              "Effect": "Allow",
              "Principal": {
                "AWS": {
                  "Fn::Join": [
                    "",
                    [
                      "arn:aws:iam::",
                      {
                        "Ref": "AWS::AccountId"
                      },
                      ":root"
                    ]
                  ]
                }
              },
              "Action": "kms:*",
              "Resource": "*"
            }
          ]
        }
      }
    },
    "Parameters": {
      "Key": {
        "Type": "String"
      },
      "Value": {
        "Type": "String"
      }
    }
  }
}