@tiraniddo released slides, demo videos, and some source code from his Zero Nights 2017 talk: Abusing Access Tokens for UAC Bypasses. Get it on his Github.
Summary:
“UAC, specifically Admin-Approval mode, has been known to be broken ever since it was first released in Windows Vista. Most of the research of bypassing UAC has focused on abusing bad elevated application behavior, auto elevation or shared registry and file resources. However, UAC was fundamentally broken from day one due to the way Microsoft implemented the security around elevated processes, especially their access tokens. This presentation will go into depth on why this technique works, allowing you to silently gain administrator privileges if a single elevated application is running. It will describe how Microsoft tried to fix it in Windows 10, and how you can circumvent their defences. It will also go into detail on a previously undocumented technique to abuse the assumed, more secure, Over-The-Shoulder elevation on Windows 10.”