I assume you have a fresh installation of kali 2.0. Then first off all add these repositories in resource.list file located at /etc/apt/sources.list, open a terminal and type
nano /etc/apt/sources.list
add following lines on it
apt-get update
after that install the kernel headers
nano /etc/apt/sources.list
add following lines on it
# regular repository
deb http://http.kali.org/kali sana main non-free contrib
deb http://security.kali.org/kali-security sana/updates main contrib non-free
# Source repository
deb-src http://http.kali.org/kali sana main non-free contrib
deb-src http://security.kali.org/kali-security sana/updates main contrib non-free
apt-get update
after that install the kernel headers
sudo apt-get install linux-headers-$(uname -r)
Then download virtualbox from https://www.virtualbox.org/wiki/Linux_Downloads.I downloaded a .deb file form "Debian 7 ("Wheezy") AMD64".Now install the virtualbox
dpkg -i virtualbox-5.0_5.0.10-104061~Debian~wheezy_amd64.deb
and That's it, Enjoy.!!
