Out of the box Bodhi 1.2 has no support to install virtualbox additions. I did the next steps to be able to install:
open a terminal (LXTerminal) and type
$sudo aptitude update
$sudo aptitude safe-upgrade
$sudo aptitude install build-essential dkms linux-headers-$(uname -r)
ref: Full screen resolution for Bodhi 1.2.1 in VirtualBox possible?