Windows 7 (Host OS, and no I don't have Admin rights) CentOS 7 (Guest, I have root privileges) Oracle VM VirtualBox 4.3
Installing CentOS 7 into VirtualBox requires that you explicitly tell the VM that the ethernet cable is plugged in. That's no big deal in and of itself, but there's some configuration to be done.
Open the file /etc/sysconfig/network/scripts/ifcfg-enp0s3
Note that the filename is based on the name of your ethernet connection. If you don't know what that is, run an ifconfig command to find out.
Modify the following two lines in the file:
BOOTPROTO=shared change to BOOTPROTO=dhcp
ONBOOT=no change to ONBOOT=yes
Reboot your CentOS and verify. That's the approach that worked for me.