Security Advisory: Multiple Vulnerabilities in Phoenix Contact Routers

Introduction

This is the fourth security advisory we release together with ONEKEY that is related to the introduction of a “zero-day identification” module that performs static code analysis on proprietary applications found within firmware uploaded to ONEKEY's platform. You can find the first three here: Asus M25 NAS Vulnerability, Multiple Vulnerabilities in NetModule Routers, and Unauthenticated Configuration Export in Multiple WAGO Products.

Phoenix Contact is a manufacturer of industrial grade routers. The vulnerabilities identified within the web management interface allow authenticated users to execute arbitrary commands with elevated privileges or to access any file on the system.

These vulnerabilities were automatically identified by our platform during one of those industrial routers' firmware scan:

All our findings were validated using an emulated device and reported to Phoenix Contact, whose PSIRT team confirmed our findings. 

Authenticated Command Injection

Summary

The web administration interface executes an OS command constructed with unsanitized user input.

Impact

A successful exploit could allow an authenticated user to execute arbitrary commands with elevated privileges.

Description

The web admin interface is written in PHP and has a page allowing for GNSS receiver configuration at /home/www-data/admin/gnssAutoAlign.php.

On line 36, the script calls exec with an unsanitized $device_id variable obtained from the POST request on line 6:

<?php
require_once('config/config.php');
if (isset($c))
    $device_id = $c;
else
    $device_id= $_REQUEST['device_id'];
$status= "disabled";
define("STATUS_FILENAME, "/tmp/status/gnss". $device_id ."/dr-auto-align");
define("ANGLES_FILENAME, "/tmp/status/gnss". $device_id ."/dr-auto-align-angles");
define("PID_FILENAME, "/run/gnss". $device_id ."/dr-auto-align.pid");

if (file_exists(STATUS_FILENAME)){
    $statusfile = fopen(STATUS_FILENAME, "r");
    $status = fread($statusfile, filesize(STATUS_FILENAME));
    fclose($statusfile);
}

$yaw = "n/a";
$pitch = "n/a";
$roll = "n/a";

if (file_exists(ANGLES_FILENAME)){
    $anglesfile = fopen(ANGLES_FILENAME, "r");
    $angles = fread($anglesfile, filesize(ANGLES_FILENAME));
    fclose($anglesfile);

    $angles = explode("\n", $angles);
    $yaw = explode("yaw: ", $angles[0])[1];
    $pitch = explode("pitch: ", $angles[1])[1];
    $roll = explode("roll: ", $angles[2])[1];
}

if (isset($_POST['toggleAlignment'])){
    if ($status == "disabled") {
        exec("/usr/local/sbin/www-scripts/various/doAutoAlignment
        " . $device_id . " > /dev/null &");
        $status = "starting";
    }
    else { 
        exec("kill $(cat ". PID_FILENAME . ")");
        $status = "stopping";
    }
}

Authenticated Path Traversal

Summary

The web administration interface is vulnerable to path traversals, which could lead to arbitrary file uploads and deletion.

Impact

By uploading a malicious PHP file within the web administration root directory, an authenticated user could gain unconstrained remote command execution.

Description

The web admin interface is written in PHP and has a page to handle what they call “SDK jobs” at /home/www-data/admin/include/sdkJobs.php. This script calls move_uploaded_file on line 320 with unsanitized user input:

if (!move_uploaded_file($_FILES["scriptUpload"]["tmp_name"], $uploadpath))

The unsanitized user input is constructed this way:

$name = trim($_POST['scriptName']);
$uploadpath = UPLOAD_DIR . "/" . $name;

Key Takeaways

This advisory serves as another example of a high-risk vulnerability gone by unnoticed by the vendor, which may end up in mission-critical environments. With increasing obligations also for operators of essential or important entities to practice third-party due diligence, automated security analysis are an effective measure to fulfill these requirements and to avoid deploying vulnerable devices in the field.

Timeline

2022-10-21 – Sent coordinated disclosure request to psirt@phoenixcontact.com

2022-10-21 – Confirmation & discussion with Phoenix Contact to explain the vulnerability.

2022-11-15 – Coordination between Phoenix Contact and ONEKEY on firmware release planning. 

2023-03-07 – Phoenix Contact releases fixed firmware and its security advisory

2023-03-28 – CERTAINITY & ONEKEY releases its advisory