azure-functionapp-system-assigned-missing: System-Assigned Managed Identities for Azure Functions

id: azure-functionapp-system-assigned-missing
info:
  name: System-Assigned Managed Identities for Azure Functions
  author: princechaddha
  severity: medium
  description: |
    Ensure that functions managed with Azure Function App are using system-assigned managed identities in order to allow secure application access to other Microsoft Azure cloud resources such as SQL databases, storage accounts, and key vaults. Using system-assigned managed identities minimizes risks, simplifies management, and maintains compliance with evolving Azure cloud services.
  impact: |
    Not using system-assigned managed identities may expose Azure Function Apps to security risks and compliance issues, complicating resource access management.
  remediation: |
    Enable system-assigned managed identities for your Azure Function Apps to enhance security and simplify the management of resource access.
  reference:
    - https://docs.microsoft.com/en-us/azure/app-service/overview-managed-identity
  tags: cloud,devops,azure,microsoft,functionapp,azure-cloud-config

flow: |
  code(1);
  for (let AppData of iterate(template.functionApps)) {
    AppData = JSON.parse(AppData);
    set("name", AppData.name);
    set("resourceGroup", AppData.resourceGroup);
    code(2);
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      az functionapp list --query '[*].{name:name, resourceGroup:resourceGroup}' --output json

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

  - engine:
      - sh
      - bash
    source: |
      az functionapp show --name $name --resource-group $resourceGroup --query 'identity.type' --output json

    matchers:
      - type: word
        words:
          - ""
          - "UserAssigned"

    extractors:
      - type: dsl
        dsl:
          - 'name + " does not use system-assigned managed identity"'
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