azure-sql-tde-cmk-not-used: Azure SQL TDE Protector Not Using BYOK

id: azure-sql-tde-cmk-not-used
info:
  name: Azure SQL TDE Protector Not Using BYOK
  author: princechaddha
  severity: medium
  description: |
    Ensure that your Microsoft Azure SQL server's Transparent Data Encryption protector (i.e. TDE master key) is encrypted with BYOK (Bring Your Own Key), also known as Customer-Managed Key (CMK), in order to protect your SQL databases with a key from your own Azure key vault. Using service-managed keys instead of BYOK can reduce control over encryption keys and security compliance.
  impact: |
    Not using BYOK for TDE can limit control over data encryption and potentially fail to meet compliance requirements that mandate encryption key management.
  remediation: |
    Configure the Transparent Data Encryption (TDE) feature of your Azure SQL server to use a Customer-Managed Key (CMK) from your own Azure Key Vault.
  reference:
    - https://docs.microsoft.com/en-us/azure/azure-sql/database/transparent-data-encryption-byok-azure-sql-configure
  tags: cloud,devops,azure,microsoft,sql,azure-cloud-config

flow: |
  code(1);
  for (let ServerData of iterate(template.serverList)) {
    ServerData = JSON.parse(ServerData);
    set("id", ServerData.id);
    code(2);
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      az sql server list --query '[*].{"id":id}'

    extractors:
      - type: json
        name: serverList
        internal: true
        json:
          - '.[]'

  - engine:
      - sh
      - bash
    source: |
      az sql server tde-key show --ids "$id" --query 'serverKeyType'

    matchers-condition: and
    matchers:
      - type: word
        words:
          - '"ServiceManaged"'

    extractors:
      - type: dsl
        dsl:
          - 'id + " is not using a Customer-Managed Key (CMK)"'
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