CVE-2019-5166 in PFC200
Summary
by MITRE
An exploitable stack buffer overflow vulnerability exists in the iocheckd service ‘I/O-Check’ functionality of WAGO PFC 200 version 03.02.02(14). A specially crafted XML cache file written to a specific location on the device can cause a stack buffer overflow, resulting in code execution. An attacker can send a specially crafted packet to trigger the parsing of this cache file.
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Analysis
by VulDB Data Team • 04/13/2024
The vulnerability identified as CVE-2019-5166 represents a critical stack buffer overflow flaw within the iocheckd service of WAGO PFC 200 industrial control devices running firmware version 03.02.02(14). This issue resides in the I/O-Check functionality, which is designed to monitor and verify input/output operations within industrial automation environments. The vulnerability stems from inadequate input validation during XML cache file processing, creating a scenario where maliciously crafted data can overwrite adjacent stack memory locations. The flaw specifically manifests when the system processes XML cache files written to predetermined locations on the device's storage, allowing an attacker to manipulate the parsing routine through network-based packet injection. This vulnerability operates at the intersection of industrial control systems security and traditional software exploitation techniques, particularly relevant to the cybersecurity landscape of industrial IoT devices.
The technical implementation of this buffer overflow occurs within the stack-based memory management of the iocheckd service, where insufficient bounds checking allows an attacker to overflow a fixed-size buffer during XML parsing operations. The vulnerability follows CWE-121 stack-based buffer overflow classification, which directly maps to the fundamental flaw where data written to a stack buffer exceeds its allocated memory space. When an attacker crafts a malicious XML cache file and places it at the designated location, the subsequent parsing operation triggers the overflow condition, potentially allowing arbitrary code execution with the privileges of the iocheckd service. This execution path aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the overflow could enable attackers to execute malicious payloads within the industrial control environment.
The operational impact of CVE-2019-5166 extends beyond simple privilege escalation, as it compromises the integrity of industrial control systems that rely on WAGO PFC 200 devices for critical infrastructure monitoring. These devices operate in environments where system availability and data integrity are paramount, making exploitation particularly dangerous for industrial control systems. Successful exploitation could allow attackers to manipulate I/O operations, potentially causing physical damage to equipment, disrupting production processes, or gaining unauthorized access to sensitive operational data. The vulnerability's network-based trigger mechanism means that attackers do not require physical access to the device, making it particularly concerning for industrial environments where network segmentation may be insufficient or compromised. The attack surface includes not only direct network access but also potential lateral movement opportunities within industrial networks where these devices may be connected to broader corporate infrastructure.
Mitigation strategies for CVE-2019-5166 should focus on immediate firmware updates provided by WAGO to address the specific buffer overflow condition in the iocheckd service. Organizations should implement network segmentation to limit access to these devices, ensuring that only authorized personnel can interact with the I/O-Check functionality. Additional protective measures include monitoring for unauthorized file creation in the specific locations where XML cache files are processed, implementing strict access controls for the affected directories, and conducting regular vulnerability assessments of industrial control systems. Network-based intrusion detection systems should be configured to detect suspicious packet patterns associated with XML parsing operations. Given the industrial nature of these devices, organizations should also consider implementing air-gapped security measures for critical systems and establishing robust incident response procedures specifically tailored for industrial control system vulnerabilities. The mitigation approach must balance security requirements with operational continuity, as industrial environments often have strict uptime requirements that make immediate patching challenging.