Create test2.html

[maekuss]

No description provided.

[hacktron-app]

⏭️ Hacktron Security Check — Skipped

Reason: PR review limit reached for this billing period. Spillover billing is available for this org but is not enabled.

Ask your org owner to enable spillover billing on the billing page, or wait for the next billing cycle.

Go to: https://app.hacktron.ai/dscsdsdc/billing

[hacktron-app-stg]

1 issue found across 1 file

Severity	Count
🔴 High	1

View full scan results

[hacktron-app-stg]

🔴 High: Missing Origin Validation in postMessage Listener

The message event listener in the application fails to validate the event.origin of incoming postMessage events. By accepting messages from any origin, the application fails to enforce a trust boundary, allowing any malicious website to interact with the application. The received data is then processed and injected into the DOM via innerHTML, which facilitates DOM-based Cross-Site Scripting (XSS) attacks.

Steps to Reproduce

1. Open the vulnerable page (e.g., test2.html) in a browser.
2. Open the browser's developer console.
3. Execute: window.postMessage('<img src=x onerror=alert("XSS")>', '*');
4. Observe that the alert triggers, confirming the lack of origin validation and the dangerous use of innerHTML.

# N/A: This is a client-side DOM-based vulnerability.

# This script demonstrates how an attacker can exploit the lack of origin validation.
# The payload is sent to the vulnerable window, which executes the injected script.
window.opener.postMessage('<img src=x onerror=alert(\"XSS_VULNERABILITY_CONFIRMED\")>', '*');

N/A

PoC Url: N/A

Fix with AI

Fix the following security vulnerability found by Hacktron.

File: test2.html
Lines: 1-67
Severity: high

Vulnerability: Missing Origin Validation in postMessage Listener

Description:
The message event listener in the application fails to validate the event.origin of incoming postMessage events. By accepting messages from any origin, the application fails to enforce a trust boundary, allowing any malicious website to interact with the application. The received data is then processed and injected into the DOM via innerHTML, which facilitates DOM-based Cross-Site Scripting (XSS) attacks.

Proof of Concept:
**Steps to Reproduce**

1. Open the vulnerable page (e.g., test2.html) in a browser.
2. Open the browser's developer console.
3. Execute: window.postMessage('<img src=x onerror=alert(\"XSS\")>', '*');
4. Observe that the alert triggers, confirming the lack of origin validation and the dangerous use of innerHTML.

```python
# N/A: This is a client-side DOM-based vulnerability.
```

```bash
# This script demonstrates how an attacker can exploit the lack of origin validation.
# The payload is sent to the vulnerable window, which executes the injected script.
window.opener.postMessage('<img src=x onerror=alert(\"XSS_VULNERABILITY_CONFIRMED\")>', '*');
```

```bash
N/A
```


PoC Url: N/A

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

---

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]

!valid