Comment 1 for bug 129254

and even the rules is added it still may not work, check this link https://wiki.ubuntu.com/VirtualboxHostNetworkingAndWIFI, and the excerpt.

"""
UPDATE July 29: it seems that since a few updates (don't know which one unfortunately) the ownership of /dev/net/tun is reverted to root:root after each reboot so we have to chown and chmod everytime. There must be a rule in udev that we can change or create a script and link it in /etc/rc2.d. I am okay to change a udev rule IF it works, so far it does not.
Personally, I changed the ownership of /lib/udev/devices/net/tun so that /net/dev/tun is created (copied apparently) with the correct permissions. (reboot necessary afterwards unless someone has another solution)

sudo chgrp uml-net /lib/udev/devices/net/tun
sudo chmod g+rw /lib/udev/devices/net/tun
"""