A Deep Dive into the GetProcessHandleFromHwnd API

In my previous blog post I mentioned the GetProcessHandleFromHwnd API. This was an API I didn’t know existed until I found a publicly disclosed UAC bypass using the Quick Assist UI Access application. This API looked interesting so I thought I should take a closer look. I typically start by reading the documentation for an API I don’t know about, assuming it’s documented at all. It can give you an idea of how long the API has existed as well as its security properties. The documentation’s remarks contain the following three statements that I thought were interesting: If the caller has UIAccess