This Metasploit module exploits a vulnerability found in Apple Safari on OSX platform. A policy issue in the handling of file:// URLs may allow arbitrary remote code execution under the context of the user. In order to trigger arbitrary remote code execution, the best way seems to be opening a share on the victim machine first (this can be SMB/WebDav/FTP, or a fileformat that OSX might automount), and then execute it in /Volumes/[share]