Resizing a vitual disk on VirtualBox is possible if the virutal disk is vdi or vhd and it is dynamic
If resizing size of the disk to 16G byte:
> "c:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd CentOS7.vdi --resize 16384
> "c:\Program Files\Oracle\VirtualBox\VBoxManage.exe" --version
5.0.0r101573
Reference:
http://virtual-soft1.nnn2.com/?p=384 (Japanese)
