X-Frame-Options not working IIS web.config - iis

Question

Our site is not currently safe from clickjacking, so I went into the web.config and added
<system.webServer>
<httpProtocol>
<customHeaders>
<add name="X-Frame-Options" value="DENY" />
</customHeaders>
</httpProtocol>
</system.webServer>
This is very straight forward code. My issue is that it's just not working. The questions I have are:
Is there a way for me to see if the X-Frame-Options is in the header response? I looked for it with httpfox and got nothing, so I can't verify if the web.config is actually putting things in the header.
Why is this not working? What can I do to test or move forward?
I did try to add it in the Global.asax in the Application_Start method, but I cant seem to "hit" this method when I debug; it does not hit breakpoints.
private void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
HttpContext.Current.Response.AddHeader("x-frame-options", "DENY");
LogHelper.Info("Cost of Care Web Application Starting");
}
I would like to add that I have tried to add it straight into the head tag and I've also tried to add it in a meta tag like so
<meta http-equiv="X-Frame-Options" content="deny">

Answer 1

The X-Frame-Options header can be used to control whether a page can be placed in an IFRAME. Because the Framesniffing technique relies on being able to place the victim site in an IFRAME, a web application can protect itself by sending an appropriate X-Frame-Options header.
To configure IIS to add an X-Frame-Options header to all responses for a given site, follow these steps:
Open Internet Information Services (IIS) Manager.
In the Connections pane on the left side, expand the Sites folder and select the site that you want to protect.
Double-click the HTTP Response Headers icon in the feature list in the middle.
In the Actions pane on the right side, click Add.
In the dialog box that appears, type X-Frame-Options in the Name field and type SAMEORIGIN or DENY in the Value field.
Click OK to save your changes.

Answer 2

Since my comments answered the question here's the end result:
For some reason setting the X-Frame-Options in web.config doesn't seem to actually work even though the documentation makes it sound like it should.
An easy work around is to set the headers manually using:
Response.AddHeader("X-Frame-Options", "DENY");
If you need this set for every request with no exceptions you can add the Application_BeginRequest to Global.asax:
protected void Application_BeginRequest()
{
Response.AddHeader("X-Frame-Options", "DENY");
}

Answer 3

The answer of siva.k does not work in connection with MVC5 as the header is generated twice here. The following code should work:
protected void Application_Start()
{
// MVC5 generates the "X-Frame-Options SAMEORIGIN" header by default, the following line disables the default behaviour
System.Web.Helpers.AntiForgeryConfig.SuppressXFrameOptionsHeader = true;
}
protected void Application_BeginRequest()
{
Response.AddHeader("X-Frame-Options", "DENY");
}
The SuppressXFrameOptionsHeader flag was mentioned here: https://stackoverflow.com/a/20262211/3936440

Answer 4

<system.webServer>
<httpProtocol>
<customHeaders>
<add name="Content-Security-Policy" value="default-src: https:; frame-ancestors 'self' X-Frame-Options: SAMEORIGIN" />
</customHeaders>
</httpProtocol>
</system.webServer>
Your web.config entry needs to be under content security policy to make use of current coding not previously depreciated. The value under content security policy of value="default-src: https: is unique to your website.
The content that matters is what comes after 'value="default-src: https:' but most importantly is contained within Content Security Policy.

Answer 5

Here is another thing to consider:
If you have a separate back-end and UI projects (as is very common for REST based sites), make sure that you put X-Frame-Options in the UI web.config. Your API is probably allowing cross site calls so adding the header to your API project would make no sense.

Answer 6

I found that some file types (.asp and .htm files) were getting the X-Frame-Options header added by this mechanism and others (.js) weren't. Using the IIS Admin utility I removed the header from the application level and added it at the server level, and then all files were getting the header added.