The packaged vagrant box from Ubuntu contains outdated Virtual Box Guest Additions. Most of the time this shouldn't be a problem, but if you want to update them I recommend this procedure:
- Install the vagrant-vbguest plugin: vagrant plugin install vagrant-vbguest
- Boot the vm without provisioning: vagrant up --no-provision
- Login with vagrant ssh and run sudo apt-get -y -q purge virtualbox-guest-dkms virtualbox-guest-utils virtualbox-guest-x11
- Logout and vagrant halt
- vagrant up --provision
https://github.com/TryGhost/Ghost-Vagrant#updating-virtual-box-guest-additions