Debian 7 install VirtualBox

in terminal as root

gedit /etc/apt/sources.list


add next lines


deb http://download.virtualbox.org/virtualbox/debian wheezy contrib 
deb http://download.virtualbox.org/virtualbox/debian squeeze contrib non-free

save and close

wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -

OK - if done

sudo apt-get update

sudo apt-get install virtualbox-4.3