You can protect yourself to some extent by not using Safari. Current versions of Chrome and Firefox both work with Snow Leopard and get regulat security updates. You deal with the ntpd problem by following these instructions:
http://www.macissues.com/2014/12/24/how-to-manually-patch-ntp-for-os-x-10-6-and- 10-7/
I've followed this procedure successfully on four Snow Leopard drives. I am very cautious generally about doing anything using Terminal (lousy typing skills, no UNIX expertise, etc.) but managed to get all the parts assembled and do it. Haven't gotten it to work with the one Lion drive I have.
You can also find guides to patching the bash vulnerability. http://tenfourfox.blogspot.com/2014/09/bashing-bash-one-more-time-updated.html
You could also invest in Parallels or Fusion and run a newer OS X version in a virtual machine alongside your Snow Leopard systems.