Right after BackBox Linux installation in VirtualBox, please click on Devices – Insert Guest Additions CD image


…then login to BackBox Linux over ssh and run next commands

# Install dkms
sudo apt-get install dkms

# Find Guest Addition cd point
sudo blkid

In our case it’s under /dev/sr0


# Mount CD on some temp folder
sudo mkdir /tmp/DVD
sudo mount /dev/sr0 /tmp/DVD
cd /tmp/DVD

# Run Installation
sudo ./VBoxLinuxAdditions.run

After installation just reboot machine and that would be that.

sudo reboot