CVE-2019-25235

Executive Summary

CVE-2019-25235 is an authentication bypass vulnerability in Smartwares HOME easy version 1.0.9. The flaw allows unauthenticated attackers to access administrative web pages by disabling JavaScript in their browser. This bypasses client-side validation checks, enabling navigation to multiple administrative endpoints and exposing sensitive system information. The vulnerability has a CVSS score of 0.0 (likely uncalculated or placeholder), but based on the vector, it is assessed as High severity due to the ease of exploitation and potential for information disclosure. No official patch has been released, and the vendor status is unknown.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary embedded web application in Smartwares HOME easy IoT devices.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Base Score: 7.5 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: High. The vulnerability is trivial to exploit (disabling JavaScript) and requires no authentication. Attackers can extract sensitive system information from administrative endpoints.

Deep Dive & Mechanics

The Smartwares HOME easy web interface relies on client-side JavaScript for access control. When JavaScript is enabled, the application checks user authentication before rendering administrative pages. However, if JavaScript is disabled, these checks are bypassed entirely, and the server serves administrative content directly to any unauthenticated user.

Root Cause: The server does not enforce authentication on administrative endpoints; it relies solely on client-side JavaScript to restrict access. This is a classic example of CWE-306: Missing Authentication for Critical Function.

Attack Flow:

1. Attacker identifies a Smartwares HOME easy device on the network.
2. Attacker configures their browser to disable JavaScript.
3. Attacker navigates to administrative URLs (e.g., /admin, /config, /status).
4. The server returns sensitive data (device configuration, network details, user credentials) without requiring login.

Impact: Full disclosure of device configuration, Wi-Fi credentials, and other sensitive data. This could enable further attacks on the internal network.

Vulnerable vs. Patched Code

Vulnerable Code (Client-Side Check):

// Vulnerable: Authentication check only on client side
if (userAuthenticated) {
    // Show admin panel
    document.getElementById('adminPanel').style.display = 'block';
} else {
    // Redirect to login
    window.location.href = '/login.html';
}

Patched Code (Server-Side Enforcement):

# Patched: Server-side authentication required
from flask import session, abort

@app.route('/admin')
def admin_panel():
    if 'user_id' not in session:
        abort(401)  # Unauthorized
    # Serve admin content
    return render_template('admin.html')

Note: No official patch has been released. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target: Smartwares HOME easy device (firmware 1.0.9)
• Attacker machine with a web browser (e.g., Firefox, Chrome)
• Network access to the device

Steps:

1. Disable JavaScript in the browser:
   • Firefox: about:config → set javascript.enabled to false
   • Chrome: Settings → Privacy and Security → Site Settings → JavaScript → Blocked
2. Navigate to the device IP (e.g., http://192.168.1.100)
3. Access administrative endpoints:
   • http://192.168.1.100/admin
   • http://192.168.1.100/config
   • http://192.168.1.100/status
4. Extract sensitive data (Wi-Fi SSID/password, device tokens, etc.)

Example cURL command:

curl --user-agent "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36" --header "Accept: text/html" http://192.168.1.100/admin

Blue Team (Detection & Defense)

Detection:

• Monitor for requests to /admin, /config, /status from unauthenticated IPs.
• Look for HTTP headers indicating JavaScript disabled (e.g., missing X-Requested-With: XMLHttpRequest).
• Alert on multiple rapid requests to administrative endpoints.

Defense:

• Implement server-side authentication for all administrative endpoints.
• Use a reverse proxy (e.g., Nginx) to enforce authentication.
• Deploy a Web Application Firewall (WAF) to block direct access to admin paths.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP GET requests to /admin, /config, /status without prior login.
• User-Agent strings with JavaScript disabled (e.g., Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)).
• Source IPs from external networks accessing internal device IPs.

Host IOCs:

• Device logs showing access to admin pages without authentication.
• Unusual traffic to port 80/443 on the Smartwares device.

File IOCs:

• None specific; this is a network-based vulnerability.

Detection Engineering

YARA Rule

rule CVE_2019_25235_Authentication_Bypass {
    meta:
        description = "Detects Smartwares HOME easy authentication bypass attempts"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2019-25235"
    strings:
        $admin_path = "/admin"
        $config_path = "/config"
        $status_path = "/status"
        $no_js = "javascript.enabled=false" nocase
    condition:
        any of ($admin_path, $config_path, $status_path) and $no_js
}

Sigma Rule

title: Smartwares HOME easy Authentication Bypass
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated access to administrative endpoints on Smartwares HOME easy devices
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem:
            - '/admin'
            - '/config'
            - '/status'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin access after authentication (if server-side auth is implemented)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2019-25235 Smartwares HOME easy Authentication Bypass"; flow:to_server,established; content:"GET"; http_method; content:"/admin"; http_uri; nocase; content:"/config"; http_uri; nocase; content:"/status"; http_uri; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote access to the Smartwares device if not required.
2. Place the device behind a firewall and restrict access to trusted IPs only.
3. Monitor logs for unauthorized access attempts.

Long-Term Fix:

• Since no official patch exists, consider replacing the device with a more secure alternative.
• Implement a reverse proxy (e.g., Nginx) with authentication in front of the device.
• Contact Smartwares for a firmware update.

Workaround:

• Use a VPN to access the device, ensuring only authenticated users can reach it.
• Block JavaScript-disabled browsers at the network level (e.g., via User-Agent filtering).

Valters IT
Securing Digital Frontiers