After reading blogs and some stackoverflow answers while building a chrome extension, I had for some reason thought that we cannot make an ajax call to a REST API hosted on server that comes under another domain than the hosted page. Is this correct? While developing my extension, I mistakenly made a call from a content script on clicking a button on my extension UI (UI is injected into the DOM using content script). I did not ran into any error. Everything went smooth. The host page in my test case is infact a page from stack overflow, and the REST API is hosted on my localhost. Could it be because the api was on local host?
From Chrome XHR documentation:
Regular web pages can use the XMLHttpRequest object to send and receive data from remote servers, but they're limited by the same origin policy. Extensions aren't so limited. An extension can talk to remote servers outside of its origin, as long as it first requests cross-origin permissions.
Furthermore, from the Content Script documentation:
Content scripts can also make cross-site XMLHttpRequests to the same sites as their parent extensions [...]
So the only thing you need is to add your API endpoint to host permissions in the manifest:
"permissions" : [
"*://api.example.com/*"
]
My current understanding is that the only way to display external web pages in the WinJS app is to use iframes. This seems to be a limitation, since I am not able to embed youtube links or twitter search links.
eg. http://www.youtube.com/watch?v=diP-o_JxysA
How do I go about displaying these webpages? Are there any workarounds for this limitation other than the run your own proxy solutions.
You cannot without running your own proxy and modifying the headers, or modifying the headers directly on the host server.
Note that for other types of resources, like login pages that don't like to be iframed (e.g. Salesforce.com), you can use the WebAuthenticationBroker.
This thread was created back in 2008 Restricting IFRAME access in PHP
I am looking to do almost the exact same thing. i.e. I want to have sites which are publicly accessible as long as they are being viewed from a specific iFrame, from a specific app. The IFrame app will have user authentication giving them access to urls outside the core application. The urls are all likely to be built using Open Source PHP tools e.g. Wordpress.
Both the viewing iFrame and the viewed sites/pages will be owned by us.
Have there been any developments in last few years on ways to do this?
For various reasons not related to this particular issue, I am considering using the serverside RIA framework Vaadin (JAVA) for building the app that will contain the iFrame viewer.
The demo of the embed widget is here http://demo.vaadin.com/sampler#WebEmbed Looking at the page source I don't see anywhere that the address of the embedded webpage is displayed. So to some extent I wonder if I can hide my urls from search engines, give them very long, randomly generated URI's and maybe they will be impossible to find anyway?
You should be able to modify a framekiller to do the opposite. A framekiller is a piece of javascript to prevent clickjacking by detecting if the page has been loaded within an iframe.
Limiting the iframe to load within a specific page is more difficult. Looking at the referer is easy, but also easy to bypass. If you load the iframe from an https page the referer will be blank. A better way would be to require the server to obtain a Nonce and include this in the iframe url. Such as http://iframe_url?key=difhj8j84528423j423894hfdj897 or whatever. Having the server make a request to your server would be ideal. Doing it with client side code and jsonp to fetch the nonce is problematic because an attacker could deliver modified javascript to fetch the nonce.
Since 1st Oct is coming. I am working on Secure Canvas URL stuff.
My canvas url is like canvas.example.com. I can make this domain and server SSL ready without a problem.
My question is, should every http request made by canvas.example.com also change to https?
e.g. I import some JS, CSS, images from cdn.example.com to my canvas page, should i configure cdn.example.com alos can be accessed via https, or I can just leave this domain alone, still use http to get those content?
thank you very much.
You should make all content served over https or the browser will show warnings.
Facebook policies clearly mention that all the Page Tabs and iFrame Applications shal have an SSL certificate..
Any external content like images and JS included on your site shall also come from secured hostings hence the Https:// else your shall not be complying to FB Policies..
Gives the fact that FB has been very strict on punishing defaulters i dont think any app developer can take risk ..
In Firefox or Chrome I'd like to prevent a private web page from making outgoing connections, i.e. if the URL starts with http://myprivatewebpage/ or https://myprivatewebpage/ in a browser tab, then that browser tab must be restricted so that it is allowed to load images, CSS, fonts, JavaScript, XmlHttpRequest, Java applets, flash animations and all other resources only from http://myprivatewebpage/ or https://myprivatewebpage/, i.e. an <img src="http://www.google.com/images/logos/ps_logo.png"> (or the corresponding <script>new Image(...) must not be able to load that image, because it's not on myprivatewebpage. I need a 100% and foolproof solution: not even a single resource outside myprivatewebpage can be accessible, not even at low probability. There must be no resource loading restrictions on Web pages other than myprivatewebpage, e.g. http://otherwebpage/ must be able to load images from google.com.
Please note that I assume that the users of myprivatewebpage are willing to cooperate to keep the web page private unless it's too much work for them. For example, they would be happy to install a Chrome or Firefox extension once, and they wouldn't be offended if they see an error message stating that access is denied to myprivatewebpage until they install the extension in a supported browser.
The reason why I need this restriction is to keep myprivatewebpage really private, without exposing any information about its use to webmasters of other web pages. If http://www.google.com/images/logos/ps_logo.png was allowed, then the use of myprivatewebpage would be logged in the access.log of Google's ps_logo.png, so Google's webmasters would have some information how myprivatewebpage is used, and I don't want that. (In this question I'm not interested in whether the restriction is reasonable, but I'm only interested in the technical solutions and its strengths and weaknesses.)
My ideas how to implement the restriction:
Don't impose any restrictions, just rely on the same origin policy. (This doesn't provide the necessary protection, the same origin policy lets all images pass through.)
Change the web application on the server so it generates HTML, JavaScript, Java applets, flash animations etc. which never attempt to load anything outside myprivatewebpage. (This is almost impossibly hard to foolproof everywhere on a complicated web application, especially with user-generated content.)
Over-sanitize the web page using a HTML output filter on the server, i.e. remove all <script>, <embed> and <object> tags, restrict the target of <img src=, <link rel=, <form action= etc. and also restrict the links in the CSS files. (This can prevent all unwanted resources if I can remember all HTML tags properly, e.g. I mustn't forget about <video>. But this is too restrictive: it removes all dyntamic web page functionality like JavaScript, Java applets and flash animations; without these most web applications are useless.)
Sanitize the web page, i.e. add an HTML output filter into the webserver which removes all offending URLs from the generated HTML. (This is not foolproof, because there can be a tricky JavaScript which generates a disallowed URL. It also doesn't protect against URLs loaded by Java applets and flash animations.)
Install a HTTP proxy which blocks requests based on the URL and the HTTP Referer, and force all browser traffic (including myprivatewebpage, otherwebpage, google.com) through that HTTP proxy. (This would slow down traffic to other than myprivatewebpage, and maybe it doesn't protect properly if XmlHttpRequest()s, Java applets or flash animations can forge the HTTP Referer.)
Find or write a Firefox or Chrome extension which intercepts all outgoing connections, and blocks them based on the URL of the tab and the target URL of the connection. I've found https://developer.mozilla.org/en/Setting_HTTP_request_headers and thinkahead.js in https://addons.mozilla.org/en-US/firefox/addon/thinkahead/ and http://thinkahead.mozdev.org/ . Am I correct that it's possible to write a Firefox extension using that? Is there such a Firefox extension already?
Some links I've found for the Chrome extension:
http://www.chromium.org/developers/design-documents/extensions/notifications-of-web-request-and-navigation
https://groups.google.com/a/chromium.org/group/chromium-extensions/browse_thread/thread/90645ce11e1b3d86?pli=1
http://code.google.com/chrome/extensions/trunk/experimental.webRequest.html
As far as I can see, only the Firefox or Chrome extension is feasible from the list above. Do you have any other suggestions? Do you have some pointers how to write or where to find such an extension?
I've found https://developer.mozilla.org/en/Setting_HTTP_request_headers and thinkahead.js in https://addons.mozilla.org/en-US/firefox/addon/thinkahead/ and http://thinkahead.mozdev.org/ . Am I correct that it's possible to write a Firefox extension using that? Is there such a Firefox extension already?
I am the author of the latter extension, though I have yet to update it to support newer versions of Firefox. My initial guess is that, yes, it will do what you want:
User visits your web page without plugin. Web page contains ThinkAhead block that would send a simple version header to the server, but this is ignored as plugin is not installed.
Since the server does not see that header, it redirects the client to a page to install the plugin.
User installs plugin.
User visits web page with plugin. Page sends version header to server, so server allows access.
The ThinkAhead block matches all pages that are not myprivatewebpage, and does something like set the HTTP status to 403 Forbidden. Thus:
When the user visits any webpage that is in myprivatewebpage, there is normal behaviour.
When the user visits any webpage outside of myprivatewebpage, access is denied.
If you want to catch bad requests earlier, instead of modifying incoming headers, you could modify outgoing headers, perhaps screwing up "If-Match" or "Accept" so that the request is never honoured.
This solution is extremely lightweight, but might not be strong enough for your concerns. This depends on what you want to protect: given the above, the client would not be able to see blocked content, but external "blocked" hosts might still notice that a request has been sent, and might be able to gather information from the request URL.