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Some websites have code to "break out" of IFRAME enclosures, meaning that if a page A is loaded as an IFRAME inside an parent page P some Javascript in A redirects the outer window to A.

Typically this Javascript looks something like this:

<script type="text/javascript">
  if (top.location.href != self.location.href)
     top.location.href = self.location.href;
</script>

My question is: As the author of the parent page P and not being the author of the inner page A, how can I prevent A from doing this break-out?

P.S. It seems to me like it ought to be a cross-site security violation, but it isn't.

Some websites have code to "break out" of IFRAME enclosures, meaning that if a page A is loaded as an IFRAME inside an parent page P some Javascript in A redirects the outer window to A.

Typically this Javascript looks something like this:

<script type="text/javascript">
  if (top.location.href != self.location.href)
     top.location.href = self.location.href;
</script>

My question is: As the author of the parent page P and not being the author of the inner page A, how can I prevent A from doing this break-out?

P.S. It seems to me like it ought to be a cross-site security violation, but it isn't.

• javascript
• html
• iframe

Share Improve this question Follow asked Dec 15, 2008 at 19:50 Jason CohenJason Cohen 83k2626 gold badges110110 silver badges114114 bronze badges 1

• I don't think you can do much at all... if you are not the author of the frame content. – scunliffe Commented Dec 15, 2008 at 19:53

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10 Answers 10

Sorted by: Reset to default 139

With HTML5 the iframe sandbox attribute was added. At the time of writing this works on Chrome, Safari, Firefox and recent versions of IE and Opera but does pretty much what you want:

<iframe src="url" sandbox="allow-forms allow-scripts"></iframe>

If you want to allow top-level redirects specify sandbox="allow-top-navigation".

I use the sandbox attribute on the iframe element:

• allow-forms allow form submission
• allow-popups allows popups
• allow-pointer-lock allows pointer lock
• allow-same-origin allows the document to maintain its origin
• allow-scripts allows JavaScript execution, and also allows features to trigger automatically
• allow-top-navigation allows the document to break out of the frame by navigating the top-level window

Top navigation is what you want to prevent, so leave that out and it will not be allowed. Anything left out will be blocked

ex.

<iframe sandbox="allow-same-origin allow-scripts allow-popups allow-forms" src="http://www.example.com"</iframe>

Try using the onbeforeunload property, which will let the user choose whether he wants to navigate away from the page.

Example: https://developer.mozilla.org/en-US/docs/Web/API/Window.onbeforeunload

In HTML5 you can use sandbox property. Please see Pankrat's answer below. http://www.html5rocks.com/en/tutorials/security/sandboxed-iframes/

After reading the w3.org spec. I found the sandbox property.

You can set sandbox="", which prevents the iframe from redirecting. That being said it won't redirect the iframe either. You will lose the click essentially.

Example here: http://jsfiddle.net/ppkzS/1/
Example without sandbox: http://jsfiddle.net/ppkzS/

I know it has been a long time since question was done but here is my improved version it will wait 500ms for any subsequent call only when the iframe is loaded.

<script type="text/javasript">
var prevent_bust = false ;
    var from_loading_204 = false;
    var frame_loading = false;
    var prevent_bust_timer = 0;
    var  primer = true;
    window.onbeforeunload = function(event) {
        prevent_bust = !from_loading_204 && frame_loading;
        if(from_loading_204)from_loading_204 = false;
        if(prevent_bust){
            prevent_bust_timer=500;
        }
    }
    function frameLoad(){
        if(!primer){
            from_loading_204 = true;
            window.top.location = '/?204';
            prevent_bust = false;
            frame_loading = true;
            prevent_bust_timer=1000;
        }else{
            primer = false;
        }
    }
    setInterval(function() {  
        if (prevent_bust_timer>0) {  
            if(prevent_bust){
                from_loading_204 = true;
                window.top.location = '/?204';
                prevent_bust = false;
            }else if(prevent_bust_timer == 1){
                frame_loading = false;
                prevent_bust = false;
                from_loading_204 = false;
                prevent_bust_timer == 0;
            }



        }
        prevent_bust_timer--;
        if(prevent_bust_timer==-100) {
            prevent_bust_timer = 0;
        }
    }, 1);
</script>

and onload="frameLoad()" and onreadystatechange="frameLoad();" must be added to the frame or iframe.

Since the page you load inside the iframe can execute the "break out" code with a setInterval, onbeforeunload might not be that practical, since it could flud the user with 'Are you sure you want to leave?' dialogs.

There is also the iframe security attribute which only works on IE & Opera

:(

In my case I want the user to visit the inner page so that server will see their ip as a visitor. If I use the php proxy technique I think that the inner page will see my server ip as a visitor so it is not good. The only solution I got so far is wilth onbeforeunload. Put this on your page:

<script type="text/javascript">
    window.onbeforeunload = function () {                       
         return "This will end your session";
    }
</script>

This works both in firefox and ie, thats what I tested for. you will find versions using something like evt.return(whatever) crap... that doesn't work in firefox.

try:

<iframe sandbox=" "></iframe>

Maybe this would be useful for someone. As an owner of the parent page I didn't want the iframe to change it's location, so I subscribed for the onload event of the iframe and correct it's src if it has changed. The iframe blinks, but that was ok for my case.

    var iframe = document.getElementById("iframeId");
    var iframeLoaded = 0;
    var originalUrl = "https://example.com";
    iframe.onload = function () {
      iframeLoaded++;
      if(iframeLoaded > 1) {
         iframeLoaded = 0;
         iframe.setAttribute(originalUrl);
      }
    };

By doing so you'd be able to control any action of the framed page, which you cannot. Same-domain origin policy applies.

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