CrackMapExec (aka CME) is a tool that helps utilize and automate the security assessment of large Active Directory networks.
It was created with secrecy in mind. CME follows the idea of "Living off the Land": abusing embedded functions and Active Directory protocols to achieve its functionality and allowing it to avoid most endpoint protection / IDS / IPS programs.
Although intended to be used primarily for offensive purposes, the CME can be used to find possible configuration and simulate attack scenarios.
You can download the program from here.