CVE-2025-41734: Metz-connect Ewio2-m RCE Vulnerability

CVE-2025-41734 Overview

CVE-2025-41734 is a critical Remote File Inclusion (RFI) vulnerability affecting Metz-Connect EWIO2 series industrial I/O devices. An unauthenticated remote attacker can execute arbitrary PHP files and gain full access to affected devices. This vulnerability requires no authentication, allowing attackers on the network to completely compromise vulnerable EWIO2 devices without any user interaction.

Critical Impact

Unauthenticated attackers can achieve complete device takeover by remotely executing arbitrary PHP code, potentially compromising industrial control systems and connected infrastructure.

Affected Products

• Metz-Connect EWIO2-M (all firmware versions)
• Metz-Connect EWIO2-M-BM (all firmware versions)
• Metz-Connect EWIO2-BM (all firmware versions)

Discovery Timeline

• 2025-11-18 - CVE-2025-41734 published to NVD
• 2025-11-21 - Last updated in NVD database

Technical Details for CVE-2025-41734

Vulnerability Analysis

This vulnerability is classified under CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program), commonly known as Remote File Inclusion. The EWIO2 series devices contain a PHP-based web interface that fails to properly validate and sanitize user-supplied input before including it in PHP file operations.

The vulnerability allows unauthenticated remote attackers to inject malicious PHP code or include external PHP files hosted on attacker-controlled servers. Upon successful exploitation, the attacker gains the ability to execute arbitrary commands with the privileges of the web server process, effectively providing complete control over the device.

Given the industrial nature of these I/O devices, successful exploitation could allow attackers to manipulate physical outputs, read sensor data, pivot to other network-connected systems, or disrupt critical industrial processes.

Root Cause

The root cause of this vulnerability lies in improper input validation within the PHP application running on the EWIO2 devices. The application accepts user-controlled parameters that are directly used in PHP include(), require(), or similar file inclusion functions without adequate sanitization or validation. This allows attackers to specify arbitrary file paths, including remote URLs pointing to malicious PHP scripts.

Attack Vector

The attack can be executed remotely over the network without any authentication requirements. An attacker can craft malicious HTTP requests to the vulnerable endpoint, specifying a URL to an external PHP file or a path to a locally accessible file containing malicious code. The attack does not require user interaction and can be automated for mass exploitation.

The exploitation mechanism involves sending specially crafted requests that manipulate file inclusion parameters. When the vulnerable PHP code processes these requests, it includes and executes the attacker-specified file, resulting in arbitrary code execution on the target device. For detailed technical information, refer to the CERT@VDE Security Advisory VDE-2025-097.

Detection Methods for CVE-2025-41734

Indicators of Compromise

• Unusual HTTP requests to the EWIO2 web interface containing external URLs or path traversal sequences in parameters
• Web server logs showing requests with http:// or https:// URLs embedded in GET or POST parameters
• Unexpected outbound connections from EWIO2 devices to external IP addresses
• Newly created files or modifications to existing PHP files on the device filesystem

Detection Strategies

• Monitor network traffic for HTTP requests to EWIO2 devices containing suspicious patterns such as http://, https://, or path traversal sequences (../)
• Implement intrusion detection rules to alert on file inclusion attack patterns targeting EWIO2 web interfaces
• Deploy network segmentation monitoring to detect any anomalous communication from industrial control segments

Monitoring Recommendations

• Enable comprehensive logging on network firewalls protecting EWIO2 device segments
• Implement application-layer inspection for HTTP traffic destined to industrial IoT devices
• Configure SIEM alerts for reconnaissance patterns targeting Metz-Connect device management interfaces
• Monitor for unusual process execution or file system changes on EWIO2 devices if such capabilities are available

How to Mitigate CVE-2025-41734

Immediate Actions Required

• Isolate affected EWIO2 devices from untrusted network segments immediately
• Implement strict network access controls to limit which systems can communicate with EWIO2 devices
• Block external network access from EWIO2 devices to prevent remote file inclusion from external sources
• Review device logs for any signs of prior exploitation attempts

Patch Information

Organizations should monitor the CERT@VDE Security Advisory VDE-2025-097 for firmware updates and official remediation guidance from Metz-Connect. Apply security patches as soon as they become available from the vendor.

Workarounds

• Segment EWIO2 devices onto isolated network VLANs with restricted access
• Implement firewall rules blocking all inbound connections except from authorized management stations
• Disable or restrict access to the web management interface if not operationally required
• Configure egress filtering to prevent EWIO2 devices from establishing connections to external networks

# Example network segmentation firewall rule (iptables)
# Restrict access to EWIO2 devices to authorized management network only
iptables -A FORWARD -d 192.168.10.0/24 -s 10.0.0.0/24 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.168.10.0/24 -s 10.0.0.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d 192.168.10.0/24 -j DROP