Vulnerability Discussion
The macOS built-in iCloud document synchronization service must be disabled to prevent organizational data from being synchronized to personal or nonapproved storage.
Apple's iCloud service does not provide an organization with enough control over the storage and access of data and, therefore, automated document synchronization must be controlled by an organization approved service.
Check
Verify the macOS system is configured to disable iCloud Document synchronization with the following command:
/usr/bin/osascript -l JavaScript << EOS
$.NSUserDefaults.alloc.initWithSuiteName('com.apple.applicationaccess')\
.objectForKey('allowCloudDocumentSync').js
EOS
If the result is not "false", this is a finding.
Fix
Configure the macOS system to disable iCloud Document synchronization by installing the "com.apple.applicationaccess" configuration profile.