chrome detected unusual code on this page and blocked it to protect your personal information

Question

Problem :

My working PHP page with an iframe inside suddenly stopped started giving following error

chrome detected unusual code on this page and blocked it to protect your personal information

Answer 1

I had faced the same issue recently.

After doing lot of research i found the solution on this issue.

I found that Chrome changed its default implementation of X-XSS-Protection to 'X-XSS-Protection: 1; mode=block'

So the fastest solution according to me is to disable X-XSS-Protection by sending just a value of 0 from the server.

Followig is example of how to do it from PHP

header("X-XSS-Protection: 0");

Further Readings:

https://bugs.chromium.org/p/chromium/issues/detail?id=654794

Answer 2

After searching  web found that Chrome changed its default implementation of X-XSS-Protection to 'X-XSS-Protection: 1; mode=block' (reference)

So the latest solution (and concerning the least change in code) is to disable X-XSS-Protection by sending a value of 0 from the server.

Here is the process how to do it from PHP

header("X-XSS-Protection: 0");

This is occured by a webpage displaying HTML that was POST'd to it, at the time that HTML contains JS event triggers, for example :

<p class="someParagraph" onClick="doTheMagicThing();">

In case you have an iframe, that accepts text like this in a POST or a forum, and you show that text, as well, thereafter Chrome will issue the error (and successfully block the page), if not you have the X-XSS-Protection header disabled.

This error message is triggered at the time Google  Chrome conceives a “cross-site scripting” attack is occuring. These attacks occur at the time a browser is tricked into rendering HTML or JavaScript that is not intended to be a part of the website being shown.

In case you administer the website

In case you’re viewing this message on a website you administer, and it’s occuring at the time usual usage, for example submitting a form, you can inhibit it by including a page header to the POST submission.

For PHP

header('X-XSS-Protection:0');

For ASP.net

HttpContext.Response.AddHeader("X-XSS-Protection","0");