CVE-2025-40593 in SIMATIC CN 4100
Summary
by MITRE • 07/08/2025
A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0). The affected application allows to control the device by storing arbitrary files in the SFTP folder of the device. This could allow an attacker to cause a denial of service condition.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/21/2025
The vulnerability identified in SIMATIC CN 4100 devices represents a critical security flaw that undermines the integrity and availability of industrial control systems. This issue affects all versions prior to V4.0 and stems from insufficient file validation mechanisms within the device's SFTP implementation. The SIMATIC CN 4100 is a programmable logic controller designed for industrial automation environments, making this vulnerability particularly concerning for operational technology infrastructure. The device's SFTP folder functionality, intended for legitimate file transfers and configuration management, has been found to accept arbitrary file uploads without proper sanitization or access controls.
The technical flaw manifests through the absence of proper input validation and file type restrictions within the SFTP service implementation. An attacker can exploit this weakness by uploading malicious or specially crafted files to the SFTP folder, which then get processed by the device's internal systems. This arbitrary file storage capability bypasses normal security boundaries and allows unauthorized manipulation of the device's operational environment. The vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-73, which covers external control of filename or path. The lack of proper file validation creates a pathway for attackers to potentially execute arbitrary code or manipulate system behavior through carefully constructed file uploads.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it creates opportunities for more sophisticated attacks within industrial control environments. A successful exploitation could result in complete system compromise, leading to unauthorized access to critical manufacturing processes or disruption of production workflows. The SIMATIC CN 4100 operates within environments where availability and reliability are paramount, making denial of service conditions particularly damaging. Attackers could leverage this vulnerability to cause extended downtime, potentially resulting in significant financial losses and safety risks in industrial operations. The vulnerability's impact is amplified in environments where these devices are part of larger industrial control networks, as it could serve as a stepping stone for lateral movement attacks.
Mitigation strategies should prioritize immediate firmware updates to version V4.0 or later, which address the identified file handling vulnerabilities. Network segmentation and access controls should be implemented to limit exposure of these devices to untrusted networks, following principle of least privilege concepts. Regular security assessments of industrial control systems should include evaluation of file transfer mechanisms and SFTP configurations. Organizations should implement monitoring solutions to detect unusual file upload activities in SFTP folders and establish incident response procedures for potential exploitation attempts. The vulnerability demonstrates the importance of secure configuration management in industrial environments, as highlighted by ATT&CK technique T1195.001 for content injection and T1499.004 for network denial of service. Device administrators should also consider implementing network-based firewalls and access control lists to restrict SFTP access to authorized personnel only, reducing the attack surface and preventing unauthorized file uploads that could lead to system compromise.