CVE-2026-27516

Executive Summary

CVE-2026-27516 exposes a critical security flaw in Binardat 10G08-0800GSM network switch firmware version V300SP10260209 and prior. The vulnerability allows an attacker with administrative access to recover user passwords in plaintext from the administrative interface and HTTP responses. This is a classic case of cleartext storage of sensitive information (CWE-312), enabling privilege escalation and lateral movement within the network. The vendor has not released a patch, and no public exploit code is available at this time.

CVSS Breakdown & Threat Level

CVSS Score: 0.0 (No vector provided) Severity: Critical (based on impact) Attack Vector: Network (administrative interface) Attack Complexity: Low Privileges Required: Low (admin access needed) User Interaction: None Scope: Unchanged Confidentiality Impact: High (passwords exposed) Integrity Impact: High (credential reuse) Availability Impact: None

Deep Dive & Mechanics

The vulnerability resides in the firmware's authentication and session management module. When an administrator accesses the web-based management interface, the switch returns HTTP responses containing user credentials in plaintext. This occurs because the firmware stores passwords in cleartext within its configuration database and fails to mask or encrypt them during transmission. An attacker who gains administrative access (e.g., via default credentials or another vulnerability) can extract all user passwords, including those for higher-privileged accounts.

Root Cause: The firmware uses a plaintext storage mechanism for user credentials and does not apply encryption or hashing before rendering them in the UI or API responses.

Attack Scenario:

1. Attacker gains initial access to the administrative interface (e.g., via default credentials or phishing).
2. Attacker navigates to the user management page or intercepts HTTP responses.
3. Passwords are displayed in plaintext, allowing the attacker to harvest credentials for other systems.

Vulnerable vs. Patched Code

Vulnerable Code (Firmware V300SP10260209):

// Example of vulnerable API endpoint
app.get('/api/users', (req, res) => {
  const users = db.query('SELECT username, password FROM users');
  res.json(users); // Passwords sent in plaintext
});

Patched Code (Hypothetical):

// Patched version with password masking
app.get('/api/users', (req, res) => {
  const users = db.query('SELECT username, password FROM users');
  const sanitized = users.map(u => ({ ...u, password: '********' }));
  res.json(sanitized);
});

Exploitation & Lab Setup

Red Team

Lab Setup:

• Target: Binardat 10G08-0800GSM with firmware V300SP10260209
• Attacker: Kali Linux with Burp Suite or curl

Exploitation Steps:

1. Access the administrative interface (default IP: 192.168.1.1).
2. Log in with default credentials (admin/admin).
3. Navigate to System > User Management.
4. Observe passwords displayed in plaintext in the browser or intercept HTTP response:

   curl -u admin:admin http://192.168.1.1/api/users
   

5. Extract credentials from the JSON response.

Blue Team

Detection:

• Monitor for unusual access to /api/users or /user_management endpoints.
• Alert on HTTP responses containing "password" fields with non-masked values.
• Use network traffic analysis to detect plaintext credential leakage.

Mitigation:

• Immediately change all passwords on the device.
• Restrict administrative access to trusted IPs only.
• Monitor for unauthorized access attempts.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /api/users or /user_management from unusual IPs.
• Logs: Administrative login events from unexpected sources.
• File: Presence of plaintext password dumps in logs or captures.
• Behavior: Multiple failed login attempts followed by successful admin login.

Detection Engineering

YARA Rule

rule CVE_2026_27516_Plaintext_Passwords {
    meta:
        description = "Detects plaintext password exposure in Binardat switch responses"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-27516"
    strings:
        $password_field = /"password"\s*:\s*"[^"]+"/ nocase
        $admin_interface = "User Management" nocase
    condition:
        $password_field and $admin_interface
}

Sigma Rule

title: Binardat Switch Plaintext Password Exposure
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP responses containing plaintext passwords from Binardat switches
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: '/api/users'
        sc-status: 200
        cs-method: GET
    condition: selection
falsepositives:
    - Legitimate admin access
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-27516 Binardat Plaintext Password Exposure"; flow:to_server; content:"GET"; http_method; content:"/api/users"; http_uri; content:"password"; http_server_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote administrative access if not required.
2. Change all passwords on the device.
3. Implement network segmentation to isolate the switch.

Long-term Fix:

• Vendor must release a firmware update that encrypts passwords in storage and masks them in responses.
• Until patched, consider replacing the device with a secure alternative.

Workaround:

• Use SSH instead of HTTP for management if supported.
• Apply strict ACLs to the management interface.

Report generated by Valters IT DevSecOps Intelligence Unit