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.