PowerUpSQL is an amazing tool to audit your SQL Server instances. Not only does it do discovery of SQL Server on your AD but can also help identify common SQL Server vulnerabilities.

It can be download from below 2 links

https://github.com/NetSPI/PowerUpSQL

https://www.powershellgallery.com/packages/PowerUpSQL/

For More information on how to user PowerUpSQL goto below link:

https://blog.netspi.com/powerupsql-powershell-toolkit-attacking-sql-server/