CentOS 7 - Install Guest Additions

Installing guest additions provides additional functionality with your virtual machines, such as shared clipboard and a dynamically resizeable window.

Run the script below to install the additions.

sudo yum update -y
sudo yum install build-essential dkms module-assistant -y
sudo bash /run/media/$USER/VBOXADDITIONS_*/VBoxLinuxAdditions.run

Then just reboot.