I have a web page that renders some nested iFrames. Lets say abc.com loads def.com, that in-turn opens ghi.com in another iFrame. abc.com -> def.com -> ghi.com
ghi.com has option set to only allow some specific sites to iFrame it. What should be the setting in ghi.com to allow it to be rendered? Do we need to white list both abc.com and def.com, or only def.com, or abc.com?
I ran into this situation with X-Frame-Options when trying to allow this scenario in IE 11. I found that putting an X-Frame-Options value of "ALLOW-FROM top-level-site-domain" worked for the response in both of the nested iFrames. Using your example, both def.com and ghi.com response would set headers similar to:
"X-Frame-Options": ALLOW-FROM abc.com
As a side note, according to OWasp, setting the X-Frame-Options header to ALLOW-FROM for def.com and SAMEORIGIN for ghi.com in your example will not work.
Remember that other browsers such as Chrome support Content-Security-Policy which you'll also want to set. In our case our domains were all subdomains so our scenario worked out easily with this header using wildcards. A scenario of first.example.com -> second.example.com -> third.example.com allowed us to set the following for second and third.example.com response header:
"Content-Security-Policy": frame-ancestors 'self' https://*.example.com
Related
If I'm loading another site in an iFrame do the Content Security Policy Headers of that site have any affect on whether the site gets blocked?
e.g. if I open www.google.com in an iFrame is there any interaction between the CSP header settings on my site and the ones on google.com? Or would Google's CSP only affect what they're trying to load in the iFrame.
Of course if google had their own iFrames they'd need CSP headers to allow any 3rd party content to load. But do my CSP headers have any affect on Google's after google.com starts to load? If Google tried to load youtube.com in an iFrame and I didn't include youtube.com in my CSP whitelist would that work?
Sorry if this is a silly question, I'm trying to wrap my head around iFrames. What I'm wondering is if I need to worry about the CSP settings on the third party, especially if I'm nesting iFrames, or if I only need to worry about my CSP policy.
I think what I'm getting at is this: Once I've said "allow this 3rd party site to load" in my CSP headers can that site load whatever it wants based on their CSP headers?
Thanks!
Let's say that you have site A framing site B. Site A must not set a framing policy that denies site B and site B must not set a policy that prevents being framed by A.
Site A can set "frame-src B" to explicitly allow site B to be framed. If frame-src is not set, child-src is used as a fallback, and if that is not set, default-src is used as a fallback. If none of them are restricted, all sites can be framed.
Site B can set "frame-ancestors A" to allow framing by A. This directive has no fallback. If it is not set, any site can frame site B. If it is set, only the sites listed as valid sources can frame it.
Apart for frame-src (child-src, default-src) for the framer and frame-ancestors for the framed, there is no impact on other sites by the CSP, they each control their own sources.
CSP Header directive corresponding to iframes ,
frame-src
frame-ancestors
lets say your site xyz.com and google's site "google.com".
Site xyz.com has its own csp which can controls,
Who can load xyz.com as iframe, decided by frame-ancestors directive
Who can be loaded inside 'xyz.com' as iframe, decided by frame-src directive
same scenario applies for google.com ( whose csp can decide, whom to be loaded as iframe inside its app & whom can load google.com as iframe )
Each html document has its own csp response header, which will not interfere with its host app (parent frame) or its iframes (child frames).
xyz.com 's CSP only decides whom should load it & whom it should load as frame, it cannot control its host frame or child frame ( they are considered as separate entities )
Apart from this another header X-FRAME-OPTIONS is also available with minimal control options to decide whether a site should load as frame or not.
For detailed reference :
CSP - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
X-FRAME-OPTIONS - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
So I'm trying to avoid using (another) page rule to disable Rocketloader for one of my subdomains, since we can't use a RegEx to select multiple specific subdomains under a single page rule, and only get 3 page rules for free accounts.
According to this page:
https://support.cloudflare.com/hc/en-us/articles/216537517-Using-Content-Security-Policy-CSP-with-Cloudflare
I can just add a header to the domain to allow scripts from CloudFlare:
add_header Content-Security-Policy "script-src 'self' ajax.cloudflare.com;";
I did so in the Nginx config for that subdomain (it's a Chronograph container actually), restarted Nginx, tested to make sure it "took", which it did:
But then when I try to load the domain, it won't load, and the inspector shows this:
Not being super familiar with this, does anyone know where I screwed it up?
where I screwed it up?
First of all, here:
I can just add a header to the domain to allow scripts from CloudFlare:
add_header Content-Security-Policy "script-src 'self' ajax.cloudflare.com;";
I did so in the Nginx config
And secondly, you trusted the report-uri service, but it failed you.
You have had an issue with ajax.cloudflare.com BEFORE adding CSP header into Nginx config (otherwise, why add it). This means that you already have a CSP published via an HTTP header or a meta tag <meta http-equiv= 'Content-Security-Policy'>.
By adding the CSP header to the Nginx configuration, you have added a second policy to the pages.
Multiple CSPs work as sequential filters - all sources must pass through both CSPs to be resolved. The second CSP allows ajax.cloudflare.com host-source, but the first one still prohibits it (that you are observe in the inspector).
You have to figure out where the first CSP is published and to add ajax.cloudflare.com into it, instead of publish second CSP.
No one know what is under the hood of the report-uri and how it will react if two CSP HTTP headers or an HTTP header paired with a meta tag are published simultaneously
Have a look which CSP and how many of them the browser actually gets, the guide is here.
In case of 2 CSP headers you will see something like that:
In case of CSP meta tag you can easily check the by inspecting the HTML code.
I think the report-uri just did not expect such a situation.
I have a web app which I want to display in an iframe in web apps with different domains. Since I have added a content-security-policy header my app refuses to display in iframe. I saw that i need to add frame-ancestors options but all the examples I see are using specific domains. How can I allow it for all domains? Is "frame ancestors *;" enough? Thanks!
Briefly - yes, * allows any sources for iframe except data:.
Pls note that frame-ancestors is not supported in the meta tag <meta http-equiv='Content-Security-Policy' content="..."> (but looks like you use HTTP header to delivery CSP, so this warn not for you).
But if you really wish to allow all frame ancestors - more reliable not specify frame-ancestors directive at all, because for now Mozilla Firefox has some bugs with it.
PS: You did not attach print screen of errors in browser console - may be iframes was block by other reason than CSP?
updated after exposed CSPs details
<html>
parent page issues CSP: default-src 'self';
since frame-src omitted, it fallback to default-src and result be: frame-src 'self'
<iframe src=''></iframe>
</html>
iframe is allowed with the same scheme://host:port as parent page loads.
'self' is tricky in that if parent loaded via HTTP:, iframe via HTTPS: will blocked in CSP2-browsers. CSP3-browsers do upgrade (see para 3) HTTP: to HTTPS:, so all OK.
If parent page issue frame-ancestors * policy, it means you allow to embed it into iframe to any another webpage.
X-Frame-Options HTTP header provide the same functionality, but it's overridden if frame-ancestor is issueed.
frame-ancestor directive does not affects <iframe> embed into page who published this CSP. It affects where it allowed to embed this page.
But <iframe> could publish its own CSP with rule frame-ancestors domain1.com domain2.com to restrict it embedding to other web-pages.
That's how it works. You could play with test of frame-ancestors to clarify details for different <iframe src=/srcdoc=.
Therefore if you embeds iframe from your own domain/subdomains, it's more safe to use:
frame-ancestors 'self';
or if you use subdomains:
frame-ancestors http://example.com https://example.com http://*.example.com https://*.example.com;
Kind of a 101 question about X-Frame-Options and/or Content-Security-Policy: frame-ancestors: if one intends to develop an application using iframed production sites (on which I can adjust headers) on a local machine, would they have to add localhost to frame-ancestors in the Content-Security-Policy? Will X-Frame-Options SAMEORIGIN not work at all?
You would want to strip those headers from the framed response so they don't prevent rendering.
Locally, the only thing that applies would be frame-src coming in the localhost response allowing you to embed your production sites (not setting csp at all would also work).
Trying to publish HTTPS content (login form) using iframe onto HTTP page.
Have permission, but do not have access to source code of HTTPS page.
Standard attempts to publish iframe do not work with this HTTPS page content.
Appears that HTTPS page x-frame-option set to DENY.
Is there any way to embed/frame/etc. this HTTPS content onto HTTP page despite x-frame objections?
This is a WordPress site. Not sure if that is relevant here.
No there is not, and this actually have nothing to do with HTTP or HTTPS, it's how the X-frame-Options header works.
When a resource returns the header of X-Frame-Options: DENY, it is not possible to show it in any iframe or iframe-like window, not even one on the same site.
You said you have permission though, so perhaps you can get the service you are using to use the ALLOW-FROM option for your service. Something like this could be configured to allow your site to frame it.
X-Frame-Options: ALLOW-FROM https://example.com/