CVE-2024-23486

Executive Summary

CVE-2024-23486 identifies a critical security flaw in BUFFALO wireless LAN routers where configured credentials (e.g., admin passwords, Wi-Fi keys) are stored in plaintext. This vulnerability allows a network-adjacent unauthenticated attacker, who can access the product's login page, to retrieve these credentials. The issue stems from insecure storage practices (CWE-256) and poses a high confidentiality risk, as an attacker could gain full administrative control over the device. No public exploit code or patch is currently available, making this a high-priority issue for users of affected BUFFALO routers.

Supply Chain & Package Security

This vulnerability is not related to a software package manager (NPM, PyPI, Go, Ruby) but is a firmware-level issue in BUFFALO's embedded router software. The risk is primarily to end-users and organizations using these devices in their network infrastructure.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD) / Adjusted Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector (AV): Adjacent Network – The attacker must be on the same local network as the router.
• Attack Complexity (AC): Low – No special conditions or timing required.
• Privileges Required (PR): None – No authentication needed to access the login page.
• User Interaction (UI): None – No user action required.
• Scope (S): Unchanged – The vulnerable component is the router itself.
• Confidentiality (C): High – Full credential disclosure.
• Integrity (I): None – No data modification.
• Availability (A): None – No denial of service.

Threat Level: Medium. While the CVSS base score is moderate, the ease of exploitation (network-adjacent, no auth) and the potential for full device compromise elevate the risk for targeted attacks.

Deep Dive & Mechanics

The vulnerability lies in how BUFFALO routers store user credentials (e.g., admin password, Wi-Fi passphrase) in their configuration files or memory. Instead of using a secure hashing algorithm (like bcrypt, PBKDF2) or encryption, the credentials are stored in plaintext. This can be exploited in several ways:

1. Direct Access: An attacker on the same network can access the router's web interface (typically on port 80 or 443). By inspecting the page source, JavaScript, or making specific API calls (e.g., /cgi-bin/ endpoints), they may retrieve the plaintext password directly.
2. Configuration File Retrieval: If the router exposes a backup or configuration download feature (e.g., /cgi-bin/config.cgi), the attacker can download the configuration file and extract the plaintext credentials.
3. Memory Dump: In more advanced scenarios, an attacker could exploit other vulnerabilities (e.g., command injection) to dump the router's memory and find the plaintext credentials.

The root cause is a failure to apply secure coding practices for credential storage. The fix would involve hashing passwords with a strong, salted algorithm before storage and ensuring that any API responses or configuration exports do not expose the plaintext.

Vulnerable vs. Patched Code

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

Vulnerable Code (Conceptual - e.g., in a CGI script):

# Vulnerable: Storing password in plaintext
def save_config(username, password):
    config = f"admin_username={username}\nadmin_password={password}\n"
    with open("/etc/config", "w") as f:
        f.write(config)

Patched Code (Conceptual):

import hashlib, os

def save_config(username, password):
    salt = os.urandom(16)
    hashed_password = hashlib.pbkdf2_hmac('sha256', password.encode(), salt, 100000)
    config = f"admin_username={username}\nadmin_password_hash={hashed_password.hex()}\nadmin_password_salt={salt.hex()}\n"
    with open("/etc/config", "w") as f:
        f.write(config)

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A BUFFALO router (e.g., WSR-2533DHP series) on the same network.
• Access to the router's web interface (default IP often 192.168.11.1).

Steps:

1. Identify the Router: Use nmap to scan the local network for open ports 80/443 and identify BUFFALO devices.

   nmap -p 80,443 --open 192.168.1.0/24
   

2. Access Login Page: Open a browser and navigate to http://<router_ip>/.
3. Inspect Page Source: View the page source (Ctrl+U) and search for patterns like password, pass, pwd, or admin. Look for hidden input fields or JavaScript variables that contain the password in plaintext.

   // Example of vulnerable JavaScript
   var adminPassword = "MySecretPass123";
   

4. API Endpoint Probing: Use curl to probe common endpoints that might leak credentials.

   curl http://192.168.11.1/cgi-bin/config.cgi
   curl http://192.168.11.1/cgi-bin/status.cgi
   

5. Extract Credentials: If successful, the response will contain the plaintext password.

No public exploit code is available for this CVE.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual access to router web interfaces from internal hosts.
• Look for repeated requests to /cgi-bin/ endpoints.
• Alert on any download of configuration files.

Defense:

• Network Segmentation: Place routers on a separate VLAN from user workstations.
• Disable Remote Management: Ensure the router's web interface is not accessible from the WAN.
• Change Default Credentials: Immediately change the default admin password to a strong, unique one.
• Firmware Updates: Monitor Buffalo's support site for any future firmware updates that address this issue.
• Use a VPN: For remote management, use a VPN instead of exposing the web interface.

Indicators of Compromise (IOCs)

• Network Traffic:
  • HTTP requests to /cgi-bin/config.cgi or similar endpoints.
  • Unusual number of requests to the router's web interface from a single internal IP.
• Logs:
  • Router logs showing failed login attempts followed by a successful login from an unknown MAC address.
  • Configuration changes made outside of normal maintenance windows.
• File Hashes (if config file is retrieved):
  • The configuration file itself (e.g., config.cfg) containing plaintext passwords.
• Processes:
  • Unusual processes running on the router (if shell access is obtained).

Detection Engineering

YARA Rule

rule CVE_2024_23486_Buffalo_Plaintext_Password {
    meta:
        description = "Detects plaintext password storage in BUFFALO router config files"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-23486"
    strings:
        $password_field = "admin_password="
        $passphrase_field = "wpa_passphrase="
        $plaintext_pattern = /admin_password=[^\n]{1,50}/
    condition:
        any of ($password_field, $passphrase_field) and $plaintext_pattern
}

Sigma Rule

title: CVE-2024-23486 - Plaintext Password Retrieval from BUFFALO Router
id: 8a9b3c2d-1e5f-4a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects attempts to retrieve plaintext passwords from BUFFALO router web interfaces.
author: Valters IT
date: 2024/10/27
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem:
            - '/cgi-bin/config.cgi'
            - '/cgi-bin/status.cgi'
            - '/cgi-bin/password.cgi'
    condition: selection
falsepositives:
    - Legitimate administrative access
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-23486 - BUFFALO Router Plaintext Password Leak"; flow:to_server,established; content:"GET"; http_method; content:"/cgi-bin/config.cgi"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the Device: If possible, disconnect the BUFFALO router from the network until a patch is available.
2. Change Credentials: Change the admin password and Wi-Fi passphrase immediately. While this does not fix the storage issue, it limits the window of exposure.
3. Disable Remote Access: Ensure the router's web interface is not accessible from the internet.
4. Monitor for Updates: Regularly check the Buffalo official website for firmware updates.

Long-Term Solutions:

• Vendor Patch: Await an official firmware update from Buffalo that addresses the plaintext storage issue.
• Replace Device: If no patch is released, consider replacing the router with a model from a vendor with a better security track record.
• Network Hardening: Implement strict network segmentation and access controls to limit exposure.

Valters IT