I installed a windows 7 on the parallels desktop 9 on my mac mini with Mac os Mavericks. As I understand that there are some shared folders between Mac os x and Windows 7 virtual machine. I've been wondering whether it's safe to use Windows 7 to surf the net without anti-virus program. If the Windows 7 VM gets affected by virus, can these malware or virus affect the Mac os x host? I mean, there are any so-called cross platform virus I should pay attention to.