Network Dynamic Data Exchange (DDE) in Windows 2000 allows local users to gain SYSTEM privileges via a "WM_COPYDATA" message to an invisible window that is running with the privileges of the WINLOGON process.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6062
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2001/ms01-007