---
id: os_external_storage_access_defined
title: Access to External Storage Must Be Defined
discussion: |-
  Access to external storage _MUST_ be managed.

  NOTE: Apple's built in method using declarative device management method only allows you to set external storage management to Allowed, ReadOnly, and Disallowed.
references:
  nist:
    cce:
      macos_27:
        - CCE-XXXXX-X
      macos_26:
        - CCE-95188-9
      macos_15:
        - CCE-94188-0
    800-53r5:
      - MP-7
    800-171r3:
      - 03.08.07
  disa:
    cmmc:
      - MP.L2-3.8.7
      - MP.L2-3.8.8
  bzk:
    bio:
      - 8.12
platforms:
  macOS:
    '27.0': {}
    '26.0':
      benchmarks:
        - name: nlmapgov_plus
    '15.0':
      benchmarks:
        - name: nlmapgov_plus
    enforcement_info:
      check:
        shell: /usr/bin/plutil -convert json /var/db/ManagedConfigurationFiles/DiskManagement/DiskManagement_Settings.plist -o - | /usr/bin/jq --raw-output '.Restrictions.ExternalStorage'
        result:
          string: $ODV
      fix:
        additional_info: This is implemented by Declarative Device Management (DDM).
odv:
  hint:
    datatype: enum
    description: Allowed|ReadOnly|Disallowed
    validation:
      enumValues:
        - Allowed
        - ReadOnly
        - Disallowed
  recommended: Allowed
  nlmapgov_plus: ReadOnly
tags:
  - cmmc_lvl2
  - 800-53r5_low
  - 800-53r5_moderate
  - 800-53r5_high
  - cnssi-1253_moderate
  - cnssi-1253_low
  - cnssi-1253_high
ddm_info:
  declarationtype: com.apple.configuration.diskmanagement.settings
  ddm_key: ExternalStorage
  ddm_value: $ODV
