Here are a few quick commands that you can use to upgrade VirtualBox directly from the Linux CLI.
Check your current virtualbox version:
vboxmanage --version
Add the virtualbox repository:
sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" >> /etc/apt/sources.list.d/virtualbox.list'
Add the key:
wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -
Update:
sudo apt-get update
Install the latest version:
sudo apt-get install virtualbox-4.3
Check that you have the version you want installed:
vboxmanage --version
And finally run virtualbox:
virtualbox