URL doesn't exists when using an iframe in a Salesforce Visualforce Page.

Hi Manpreet,

Salesforce has also implemented its own defenses to "Clickjacking" attacks within the native UI. Due to this, the iFraming of Salesforce, or the iFraming of some external websites is no longer recommended. Modern browsers are forced to defend against this new kind of attack, where framing is used by malicious attackers to compromise a browser and potentially steal customer data.

In response, many browsers have implemented a new HTTP header called "X-Frame-Options," and it's gaining in popularity.

Here's the workaround to iframes

If you're encountering this problem, instead of using a web tab, a custom link can deliver the URL with the behavior set to:

• Display in new window.
• Display in existing window without sidebar or header.

Hope this helps you.