Install VirtualBox Additions in Ubuntu Guests
September 25, 2015
Ubuntu may require installing additional dependencies in order to fully install the VirtualBox guest additions. This is usually very minimal. So, before inserting the guest extensions ISO and running it, simply execute:
sudo apt-get install build-essential linux-headers-$(uname -r)
However, my latest install of Ubuntu 15.04 did not require installing any additional dependencies. Your mileage may vary.