Hello,

Yes, it is possible. Please add these lines into your custom css box:

footer#footer .inner {
background-repeat: no-repeat;
background-size: cover;
background-attachment: fixed;
background-position: left top;
background-image: url('https://104.131.255.213/specular/default/wp-content/uploads/2014/05/about3.jpg');
}

Change the image url to your need.

Best regards!