Vulnerability Discussion

The macOS system's ability to automatically synchronize a user's
passwords to their iCloud account must be disabled.

Apple's iCloud service does not provide an organization with enough control over the storage and access
of data and, therefore, password management and synchronization must be controlled by an organization
approved service.

Check

Verify the macOS system is configured to disable iCloud Keychain synchronization with the
following command:

/usr/bin/osascript -l JavaScript << EOS
$.NSUserDefaults.alloc.initWithSuiteName('com.apple.applicationaccess')\
.objectForKey('allowCloudKeychainSync').js
EOS

If the result is not "false", this is a finding.

Fix

Configure the macOS system to disable iCloud Keychain synchronization
by installing the "com.apple.applicationaccess" configuration profile.