Oracle VM VirtualBox Manager

Internet Connection on VM

I was having the same problem on Ubuntu 12.10 64bit using Virtualbox 4.2.22. Here are the steps I took to solve my problem:

Open Virtualbox Manager

Select the machine you cannot get internet on in the left pane
Click the Settings button in the top menu
Click Network in the left pane in the settings window
Switched to Bridged Adapter in the Attached to drop-down menu
Select the name of the network adapter you are currently using on your host machine. I am using wireless so I chose eth0 which is my wireless network adapter. You can check which adapter you are currently using by opening the terminal (CTRL+ALT+T by default) and running ifconfig. It will probably be the eth adapter that shows an inet addr and shows data transfer next to RX bytes.
Under Advanced, make sure the machine is using the Desktop Adapter Type
Under Advanced, make sure Promiscuous Mode is set to Allow VMs
Under Advanced, make sure Cable connected is checked on
Hit OK to save your changes
Start your VM