So I'm not sure why but I get an error message from Chrome.
Error message:
Refused to execute inline script because it violates the following Content Security Policy directive: "default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'". Either the 'unsafe-inline' keyword, a hash ('sha256-TakXxMuCq+J+ccgIY6WUXR+xy3/BdgRbqG7Y1mNRWJQ='), or a nonce ('nonce-...') is required to enable inline execution. Note also that 'script-src' was not explicitly set, so 'default-src' is used as a fallback.
jQuery:
<script type="text/javascript">
$( document ).ready(function() {
$.ajax({
type:'GET',
url:'http://api.steampowered.com/ISteamNews/GetNewsForApp/v0002/?appid=440&count=3&maxlength=300&format=json'
success: function(data){
console.log('success',data);
}
});
});
</script>
Sorry if this is a duplicate question.
I just had a hard time finding the answer to my problem.
But can someone explain why I am getting the error message that I am getting?
I want to give some extra information, so that you may understand my situation.
I was writing an app in HTML.
All the files used in the HTML other then the JSON are all from my machine.
I did not run them from any server including xampp. I simply double clicked my HTML file.
Are you writing a Chrome extension? It's not immediately clear from your question, but that's where I would expect to find this error message.
Inline script tags are not executed by extensions. The Google Content Security Policy pages state:
Inline JavaScript will not be executed. This restriction bans both
inline <script> blocks and inline event handlers (e.g. <button
onclick="...">).
The first restriction wipes out a huge class of cross-site scripting
attacks by making it impossible for you to accidentally execute script
provided by a malicious third-party. It does, however, require you to
write your code with a clean separation between content and behavior
(which you should of course do anyway, right?).
There is a way to relax this policy though
As of Chrome 46, inline scripts can be whitelisted by specifying the
base64-encoded hash of the source code in the policy. This hash must
be prefixed by the used hash algorithm (sha256, sha384 or sha512). See
Hash usage for <script> elements for an example.
Related
I am trying to load jQuery in Electron (v. 16.0.0), but I get this error:
Inside the head element I have included this line:
<meta http-equiv="Content-Security-Policy" content="script-src 'self';">
Also, inside the body element, I am trying to load jQuery like this:
<script src="https://code.jquery.com/jquery-3.6.0.min.js" integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>
I have tried so many ways to find a solution for this, but to no avail. Previously, I also tried to load jQuery like this, but it gave me a similar error, shown below:
<script>window.$ = window.jQuery = require('./libraries/jQuery/jquery.min.js');</script>
Answers to a related question did not work for me either. What should I do?
The reason Electron, or any other Web browser that implements Content Security Policy, for that matter, would correctly refuse to load a script from an arbitrary origin (URL), or even an "inline" script (e.g. script text inside a script element), is because your security policy is explicitly specified to deny such attempts, with that meta element you said you added:
<meta http-equiv="Content-Security-Policy" content="script-src 'self';">
Why did you add it? Was it there by someone else's hand? Why is it there? It's the reason why Electron denies loading of the scripts in question.
The value of the content attribute above has the effect of instructing Electron to only allow loading scripts from the same origin as the origin of the document containing the meta element. That effectively excludes every other origin like https://code.jquery.com and inline scripts (which have to be allowed explicitly in this case because self denies these). Basically, the value is to be interpreted as "only allow loading scripts from the same site". Inline scripts are not considered as "same site".
Simpler put, you yourself prohibit loading of scripts from the kind of locations you then attempt to use, with that meta element.
You need to learn how Content Security Policy mechanism works and applies in your case. You will have to decide whether you want to allow loading of scripts from domains like code.jquery.com, or whether, for example, you will only want to allow loading scripts from your website, which in turn will probably necessitate you copying the JQuery library you want to use to be served by your website. You also will have to decide if you want to allow "inline" scripts on your site, for whatever reason you may consider necessary.
The security policy mechanism itself is very useful, don't shy away from it, it's there for a reason -- to help you prevent abuse of your site users by malicious scripts loaded by other malicious scripts or mechanisms. But you need to use it correctly, obviously.
You have 2 issues because of jQuery:
script-src 'self' does not allow to load script from https://code.jquery.com/jquery-3.6.0.min.js, that's why you observe Refused to load the script 'https://code.jquery.com/jquery-3.6.0.min.js'... error.
You have to adjust your CSP at least as script-src 'self' https://code.jquery.com;.
After page loads, the jQuery pick up all scripts having $() and place them into one inline script in the <head> section. That's why you observe Refused to execute inline script ... error.
This inline script can be resolved with either 'unsafe-inline' or 'unsafe-eval' or 'nonce-value'(for jQuery > 3.4).
Allowing 'unsafe-inline' is a very harmful advice, since such CSP will not protect against XSS at all (https://youtu.be/zlH_bBQMgkc?t=717).
Also Electron does not have the technical ability to refresh the 'nonce' value.
Therefore, the most secure CSP you can do is:
script-src 'self' 'unsafe-eval' https://code.jquery.com;
or much better:
default-src 'self'; script-src 'self' 'unsafe-eval' https://code.jquery.com;
Note: Contrary to a common misconception, 'self' does not mean the Same Origin Policy, CSP interprets 'self' much more broadly.
I am working on a project in Django, where I am using a javascript from an external payment provider. Upon calling their script, they will insert a payment form embedded in my page.
The documentation on how to integrate with their service is found here. Specifically I am following step 3 and 4.
A snippet of my html is as below. Upon calling my javascript the payment form from checkout.js will be rendered as an iframe in the checkout-container-div element
<div id="checkout-container-div"> </div>
<script src="https://test.checkout.dibspayment.eu/v1/checkout.js?v=1"></script>
In my javascript, I first call my backend to get the paymentId. Then using the obtained paymentId, I am calling the external checkout.js with const checkout = new Dibs.Checkout(checkoutOptions); in order to render the payment form
document.getElementById("paymentButton").addEventListener("click", function() {
//Collect all the fields value and send it to the server
console.log("pay button clicked")
$.ajax({
url : "localDeliveryPayment",
type : "get",
success: function(response) {
if (response['paymentIdCreation'] == true) {
console.log(response);
const checkoutOptions = {
checkoutKey: response['checkoutKey'], // Replace!
paymentId: response['paymentId'],
containerId: "checkout-container-div",
};
const checkout = new Dibs.Checkout(checkoutOptions);
checkout.on('payment-completed', function (response) {
window.location = 'completed.html';
});
}
}
})
})
From Google Chrome's console I get the following error related to test.checkout.dibspayment.eu/:1
Refused to execute inline script because it violates the following Content Security Policy directive: "script-src 'self' 'sha256-NzNw/hrx7wC5UKemwLm4mwVnoDVfHDuSpmZAeKCQaqY=' 'sha256-aKaLBqGLMQ35mP/i/QmpW+s6QnrN3dNb78G9ndv1bC0=' 'sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU='". Either the 'unsafe-inline' keyword, a hash ('sha256-1XgMsIi6szxMi7JX5ZCg4KWReddGOu15C+cKuzlVaf4='), or a nonce ('nonce-...') is required to enable inline execution.
Also I see this error related to checkout.api.ts:126 POST
POST https://test.checkout.dibspayment.eu/api/v1/frontendlogs net::ERR_ABORTED 401 (Unauthorized)
There are some other errors as well that I think is related to content being blocked. I have tried to add the below meta tag to the head in my html base template.
<meta http-equiv="Content-Security-Policy"
content = "script-src 'self'
cdnjs.cloudflare.com
code.jquery.com
cdn.jsdelivr.net
stackpath.bootstrapcdn.com
test.checkout.dibspayment.eu;">
Still I got the error test.checkout.dibspayment.eu/:1
Refused to execute inline script because it violates the following Content Security Policy directive: "script-src 'self' 'sha256-NzNw/hrx7wC5UKemwLm4mwVnoDVfHDuSpmZAeKCQaqY=' 'sha256-aKaLBqGLMQ35mP/i/QmpW+s6QnrN3dNb78G9ndv1bC0=' 'sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU='". Either the 'unsafe-inline' keyword, a hash ('sha256-1XgMsIi6szxMi7JX5ZCg4KWReddGOu15C+cKuzlVaf4='), or a nonce ('nonce-...') is required to enable inline execution.
Also I tried with 'unsafe-inline' keyword in the Content-Security-Policy meta tag, but still got the same error. I have read several places that CSP is blocking for inline code execution and now is really confused if the issue at all is related to inline code execution from the external javascript, or if this error is related to something else?
The solution to this problem on integration of NETS payment service when running in Django turned out not to be fully related to content security protocol. The error I posed originally is related to CSP, but I never managed to solve it. When I used the payment demo webshop I see the same error on my browser as during my own test. The checkout was successful, therefore I figured out that the error is not only related to CSP. It turned out that adding
django_referrer_policy.middleware.ReferrerPolicyMiddleware'
to the middleware in my settings.py and followed by adding
REFERRER_POLICY = 'strict-origin'
in settings.py solved the problem.
Ok, im just lost. I opened an electron start app and added one simple code, to console log on button press. The function is in a file renderer.js and in being called in in my index.html. Why when I press the button
I get this message ....
Refused to execute inline event handler because it violates the following Content
Security Policy directive: "script-src 'self'". Either the 'unsafe-inline' keyword, a
hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution.
Why would I not be allowed to execute something inline? An external source seems more vulnerable. Can anyone clear this up for me please?
Content Security Policy is using to avoid XSS based attacks in browser.In electron the background is running in a chrome engine, so the code is actullay running in a chromium browser.This browser is prone to all security issues that a browser is having
What is Content-Security-Policy?
Content-Security-Policy is the name of a HTTP response header that modern browsers use to enhance the security of the document (or web page). The Content-Security-Policy header allows you to restrict how resources such as JavaScript, CSS, or pretty much anything that the browser loads.
you can add the following code at the top of HTML to avoid the content security issue. this new header will allow the inline code to execute
<meta http-equiv="Content-Security-Policy" content="script-src 'self';">
What this meta tag will do ?
Allows
With the above CSP policy, the following are allowed to load and execute in the browser:
<!-- allowed by 'self' -->
<script src="/js/some-file.js"></script>
<!-- allowed by https://js.example.com -->
<script src="https://js.example.com/file.js"></script>
Blocks
The Example Policy above will block the following from loading or executing in the browser:
<script src="https://attacker.example.com/file.js"></script>
I am in the process of adding CSP headers to a site that has a long way to go before it can adopt a strict policy. There are quite a few inline scripts, so I am using nonce- to allow specific inline scripts. I have found that it doesn't work on the onload attribute of a script tag with src. Here's an example:
// header:
Content-Security-Policy: script-src self https: 'nonce-d3adbe3fed'
<script async defer src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js" nonce="d3adbe3fed" onload="console.log('onload', _.VERSION)"></script>
Full working demo at https://brave-pasteur-0d438b.netlify.com/
Chrome gives the following error:
Refused to execute inline event handler because it violates the following Content Security Policy directive: "script-src self https: 'nonce-d3adbe3fed'". Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution.
The message suggests that it should be possible to enable inline event handlers with a nonce, but as far I as I can tell, nonce is only intended to work on inline scripts.
This is just a demo, but the use case is an async/deferred tracking script which loads the tracking library, then in the onload handler makes a tracking call to the loaded library.
Is it possible to use a nonce on an onload or other event handler attribute, or will I need to change my implementation? Using script-src 'unsafe-inline' or script-src-attr 'unsafe-inline' is not an option, as those are the vulnerabilities I am specifically trying to address. And putting the contents of the onload handler into a separate script following the script tag is also not an option because the script is async deferred, and needs to stay that way.
If there is a way to use nonce on an inline handler, I will accept an answer that demonstrates it. Unfortunately, at the time of writing, I don't think there is.
As a workaround, the following script exhibits the same behavior and timing as an script with async/defer and an onload handler, while satisfying the specified CSP policy:
<script nonce="d3adbe3fed">
let s = document.createElement('script');
s.src = 'https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js';
s.onload = () => console.log(_.VERSION);
document.documentElement.appendChild(s);
</script>
Of course, the long term solution is to eliminate inline scripts completely, but in the short term that isn't always feasible, and it is better to implement a more lax policy quickly, than to put it off and have no CSP at all.
As previously noted nonces won't work (at least at the moment - January of 2023) for inline JS event handlers - but you can use the less safe unsafe-hashes option if you can't or don't want to change your inline script. The procedure is below.
Generate your hash using this command:
echo -n "console.log('onload', _.VERSION)" | openssl dgst -sha256 -binary | openssl base64
and then use it like:
Content-Security-Policy: script-src 'unsafe-hashes' 'sha256-YOUR_HASH_HERE';
in this case the hash YOUR_HASH_HERE would be: is6kBKp90zgPWiqfkihufUS6bhRViGwlIg8RlEV7MgA=
I have a page that I set the script-src of the content security policy like this:
script-src 'self' *.uservoice.com *.intuit.com ajax.googleapis.com localhost:*
When I load the page with a hard-coded inline script I have created myself to test, it is blocked like expected:
Refused to execute inline script because it violates the following
Content Security Policy directive: "script-src 'self'
*.uservoice.com *.intuit.com ajax.googleapis.com localhost:* ". Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce
('nonce-...') is required to enable inline execution.
However, when I insert a new script tag dynamically, the script isn't blocked, for example, this still executes:
$("body").append("<script>alert('xss');</script>")
I am using Chrome as the browser here for testing. I was hoping that this script would be blocked as well, since that would really help to prevent xss. Is there something I can change to block this type of script injection as well?
The script you add with append or innerHtml won't be executed unless you use eval(). So it's not violating CSP.
Although this may look like a cross-site scripting attack, the result is harmless. HTML5 specifies that a tag inserted via innerHTML should not execute. 1
See script elements inserted using innerHTML do not execute when they are inserted.