When importing the Remnux ova into VirtualBox you may notice that the window sizes are inappropriate in order to fix this you will need to install the VBox Guest additions.
In order to do this. Add an optical drive in VBox to the virtual machine. Then in the menu insert Vbox guest additions and install the software.
Then you will need to follow the instructions on the website.
sudo mount /dev/sr0 /mnt/cdrom sudo /mnt/cdrom/VBoxLinuxAdditions.*