CVE-2019-5161 in PFC200
Summary
by MITRE
An exploitable remote code execution vulnerability exists in the Cloud Connectivity functionality of WAGO PFC200 versions 03.02.02(14), 03.01.07(13), and 03.00.39(12). A specially crafted XML file will direct the Cloud Connectivity service to download and execute a shell script with root privileges.
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Analysis
by VulDB Data Team • 04/13/2024
The vulnerability identified as CVE-2019-5161 represents a critical remote code execution flaw within the WAGO PFC200 industrial control devices, specifically affecting firmware versions 03.02.02(14), 03.01.07(13), and 03.00.39(12). This issue resides within the cloud connectivity functionality of these industrial automation systems, which are widely deployed in industrial environments for process control and monitoring. The affected devices are designed for harsh industrial conditions and typically operate in critical infrastructure sectors including manufacturing, energy, and process control systems where security is paramount.
The technical exploitation mechanism involves a specially crafted xml file that can be delivered to the target device through the cloud connectivity service. When the device processes this malicious xml payload, the cloud connectivity service automatically initiates a download operation from a remote server specified within the xml file. The vulnerability stems from insufficient input validation and sanitization within the xml parsing routine, allowing an attacker to inject malicious commands that are subsequently executed with root privileges. This represents a classic command injection vulnerability that has been classified under CWE-78 as improper neutralization of special elements used in os command construction, and more specifically under CWE-94 as execution of arbitrary code or commands.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with full administrative control over the affected industrial devices. Since the malicious shell script executes with root privileges, attackers can modify system configurations, install persistent backdoors, access sensitive operational data, and potentially disrupt critical industrial processes. The cloud connectivity feature, designed for remote monitoring and management, becomes a vector for attackers to gain unauthorized access to industrial control systems without requiring physical presence or local network access. This vulnerability directly impacts the integrity and availability of industrial control systems, potentially leading to production disruptions, safety hazards, or even physical damage to industrial equipment. The attack surface is particularly concerning as industrial control systems often operate in isolated networks with limited security monitoring capabilities, making such attacks difficult to detect and mitigate.
Organizations should implement immediate mitigations including network segmentation to isolate industrial control systems from general corporate networks, disabling cloud connectivity features where possible, and applying firmware updates provided by WAGO to address this vulnerability. Network monitoring should be enhanced to detect unusual outbound connections from industrial devices to external servers, which could indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices in industrial systems and aligns with ATT&CK techniques such as T1059 for command and scripting interpreter and T1071 for application layer protocol usage, highlighting the need for robust input validation and privilege separation in industrial automation systems. Additionally, organizations should conduct comprehensive vulnerability assessments of their industrial control systems to identify similar vulnerabilities in other components and ensure proper security controls are implemented across their operational technology infrastructure.