CVE-2019-5073 in PFC100
Summary
by MITRE
An exploitable information exposure vulnerability exists in the iocheckd service "I/O-Check" functionality of WAGO PFC200 Firmware versions 03.01.07(13) and 03.00.39(12), and WAGO PFC100 Firmware version 03.00.39(12). A specially crafted set of packets can cause an external tool to fail, resulting in uninitialized stack data to be copied to the response packet buffer. An attacker can send unauthenticated packets to trigger this vulnerability.
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Analysis
by VulDB Data Team • 03/15/2024
The CVE-2019-5073 vulnerability represents a critical information exposure flaw within the iocheckd service of WAGO PFC200 and PFC100 industrial control devices. This vulnerability specifically targets the I/O-Check functionality that is integral to the device's operational monitoring capabilities. The affected firmware versions indicate a widespread issue affecting multiple generations of WAGO's programmable logic controllers, which are commonly deployed in industrial environments for critical infrastructure control and automation systems. The vulnerability resides in the network service handling mechanism where the iocheckd daemon processes incoming packets for I/O monitoring purposes.
The technical implementation of this vulnerability stems from improper memory management within the packet processing pipeline of the iocheckd service. When the service receives specially crafted packets designed to trigger the I/O-Check functionality, the system fails to properly initialize stack memory variables before copying data into the response packet buffer. This uninitialized stack data exposure occurs because the service does not perform adequate validation or sanitization of input parameters before constructing the response. The flaw manifests as a classic buffer overflow condition where sensitive data from adjacent memory locations gets inadvertently included in the network response, potentially exposing system internals, configuration details, or other confidential information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a potential attack vector for adversaries seeking to gain deeper insights into the industrial control system's internal workings. Attackers can exploit this vulnerability without requiring authentication, making it particularly dangerous in industrial environments where physical security may be less stringent. The uninitialized data exposure could potentially reveal memory layout information, system configuration parameters, or other sensitive operational details that could be leveraged for more sophisticated attacks. This vulnerability aligns with CWE-1280, which specifically addresses information exposure through uninitialized memory, and represents a significant concern for industrial control systems where such exposure could lead to operational disruption or compromise of critical infrastructure.
The attack surface for this vulnerability is particularly concerning given the industrial nature of WAGO PFC devices, which are commonly deployed in manufacturing environments, power grid control systems, and other critical infrastructure applications. The unauthenticated nature of the exploit means that attackers can potentially probe systems remotely without requiring prior access credentials, making it an attractive target for reconnaissance activities. Network-based attacks can be executed from external locations, potentially allowing threat actors to gather intelligence about industrial control systems before launching more targeted attacks. Security practitioners should consider this vulnerability in the context of ATT&CK framework's T1046 technique for network service scanning and T1005 for data from local system, as it provides a method for information gathering that could be used to inform subsequent attack phases. Organizations should implement immediate mitigations including network segmentation, firewall rules to restrict access to the affected services, and firmware updates to address the uninitialized memory handling issue. The vulnerability underscores the importance of proper memory management practices in embedded systems and highlights the need for robust input validation in industrial control system components that may be exposed to untrusted network traffic.