Create sfsd.html

[maekuss]

No description provided.

[hacktron-app]

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[hacktron-app-stg]

1 issue found across 1 file

Severity	Count
🔴 High	1

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[hacktron-app-stg]

🔴 High: DOM-based Cross-Site Scripting (XSS) via insecure postMessage listener in sfsd.html

The sfsd.html file implements a window.addEventListener('message', ...) listener that fails to validate the event.origin of incoming messages. It then takes the event.data and directly assigns it to the innerHTML of the div#output element. This allows any malicious website to send a crafted postMessage to this page, leading to arbitrary JavaScript execution in the context of the page's origin. This is a clear DOM-based XSS vulnerability.

Steps to Reproduce

1. Open sfsd.html in a browser.
2. In the console of a different origin (e.g., example.com), execute:
   window.opener.postMessage('', '*');
3. The alert will execute on the sfsd.html page.

Fix with AI

Fix the following security vulnerability found by Hacktron.

File: sfsd.html
Severity: high

Vulnerability: DOM-based Cross-Site Scripting (XSS) via insecure postMessage listener in sfsd.html

Description:
The `sfsd.html` file implements a `window.addEventListener('message', ...)` listener that fails to validate the `event.origin` of incoming messages. It then takes the `event.data` and directly assigns it to the `innerHTML` of the `div#output` element. This allows any malicious website to send a crafted `postMessage` to this page, leading to arbitrary JavaScript execution in the context of the page's origin. This is a clear DOM-based XSS vulnerability.

Proof of Concept:
1. Open `sfsd.html` in a browser.
2. In the console of a different origin (e.g., `example.com`), execute:
   window.opener.postMessage('<img src=x onerror=alert(document.domain)>', '*');
3. The alert will execute on the `sfsd.html` page.

Fix this vulnerability. Only change what's necessary - don't modify unrelated code.

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Triage: Reply !fp <reason> (false positive), !valid (confirmed), or !accepted_risk <reason>. Reason is optional but improves future scans — e.g. !fp internal endpoint, not user-facing. Any other reply is saved as a triage note.

View finding in Hacktron

[maekuss]

hi