CVE-2019-5168 in PFC200
Summary
by MITRE
An exploitable command injection vulnerability exists in the iocheckd service ‘I/O-Check’ function of the WAGO PFC 200 version 03.02.02(14). An attacker can send a specially crafted XML cache file At 0x1e8a8 the extracted domainname value from the xml file is used as an argument to /etc/config-tools/edit_dns_server domain-name=<contents of domainname node> using sprintf().This command is later executed via a call to system().
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Analysis
by VulDB Data Team • 05/11/2025
The CVE-2019-5168 vulnerability represents a critical command injection flaw within the WAGO PFC 200 industrial control device, specifically affecting the iocheckd service and its I/O-Check functionality. This vulnerability stems from improper input validation and sanitization within the XML cache file processing mechanism, creating a dangerous attack vector for malicious actors targeting industrial control systems. The flaw manifests when the system processes specially crafted XML files containing domain name values that are subsequently passed directly into system commands without adequate sanitization. The vulnerability is particularly concerning within industrial environments where these devices operate as critical infrastructure components, making them attractive targets for sophisticated cyber attacks that could disrupt manufacturing processes and operational technology networks. The affected WAGO PFC 200 device version 03.02.02(14) demonstrates how legacy industrial systems often contain outdated security practices that create persistent attack surfaces.
The technical implementation of this vulnerability occurs at memory address 0x1e8a8 within the iocheckd service where the domain name value extracted from XML files undergoes dangerous string formatting operations using sprintf() function. This function concatenates the user-supplied domain name value directly into a command string that is later executed via the system() call, creating a classic command injection scenario. The sprintf() function call constructs the command "/etc/config-tools/edit_dns_server domain-name=<contents of domainname node>" by directly incorporating the unvalidated input, allowing attackers to inject malicious commands that will execute with the privileges of the iocheckd service. This represents a fundamental violation of secure coding practices and aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands. The vulnerability demonstrates how industrial control systems often lack proper input validation mechanisms, particularly when dealing with configuration data that originates from external sources.
The operational impact of CVE-2019-5168 extends beyond simple remote code execution, potentially enabling attackers to gain full control over the affected industrial control device and potentially compromise the broader industrial network. Attackers can leverage this vulnerability to execute arbitrary commands on the device, potentially leading to system compromise, data exfiltration, or disruption of critical manufacturing processes. The attack surface is particularly dangerous because it can be exploited through XML cache files that may be delivered via legitimate configuration update mechanisms or through compromised network connections. This vulnerability directly maps to ATT&CK technique T1059.001, which describes the use of command and scripting interpreters, and represents a significant risk to industrial control systems that often operate with elevated privileges and critical network access. The impact is amplified in environments where these devices are connected to operational technology networks, as successful exploitation could lead to lateral movement and further compromise of critical infrastructure.
Mitigation strategies for CVE-2019-5168 should prioritize immediate firmware updates from WAGO to address the root cause of the command injection vulnerability. Organizations should implement network segmentation to limit access to affected devices and restrict the ability of unauthorized users to upload configuration files or XML cache data. Input validation and sanitization measures must be strengthened to prevent any untrusted data from being passed directly into system command execution contexts. Security controls should include monitoring for unusual command execution patterns and implementing proper access controls for configuration update mechanisms. The vulnerability highlights the importance of following secure coding practices such as those recommended in the OWASP Secure Coding Guidelines, particularly regarding the prevention of command injection vulnerabilities. Additionally, organizations should conduct comprehensive vulnerability assessments of their industrial control systems to identify similar insecure coding practices that could create additional attack vectors, as this vulnerability represents a broader class of issues affecting industrial control systems that often lack proper security testing and validation processes.