Xprotect, File Quarantine
Mac Malware Guide : How does Mac OS X protect me?
http://www.thesafemac.com/mmg-builtin/
- File Quarantine
OS X: About the "Are you sure you want to open it?" alert (File Quarantine / Known Malware Detection)
http://support.apple.com/kb/HT3662
http://en.wikipedia.org/wiki/File_Quarantine
- Xprotect
