This extension will check for an existing .git directory on your site, which is a big security leak.
Check a website for having the .git directory public accessible.
This is a huge security issue, as all source files can be downloaded.
For more information see: https://www.jordijolink.nl/2016/09/24/ripping-a-websites-source-files/
This plugin can detect this security leak on (your) websites.