CVE-2018-7857 in Modicon M580
Summary
by MITRE
A CWE-248: Uncaught Exception vulnerability exists in all versions of the Modicon M580, Modicon M340, Modicon Quantum, and Modicon Premium which could cause a possible Denial of Service when writing out of bounds variables to the controller over Modbus.
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Analysis
by VulDB Data Team • 09/23/2023
The vulnerability described in CVE-2018-7857 represents a critical uncaught exception scenario affecting several legacy industrial automation controllers including the Modicon M580, M340, Quantum, and Premium series. This weakness falls under CWE-248, which specifically addresses the situation where an exception or error condition is not properly handled by the application code. The affected systems are widely deployed in industrial control environments where reliability and continuous operation are paramount for operational technology infrastructure.
The technical flaw manifests when these controllers receive Modbus commands that attempt to write data to memory locations beyond the allocated boundaries for variables within the controller's memory space. This out-of-bounds write operation triggers an exception that is not properly caught or managed by the controller's software architecture. The absence of proper exception handling causes the controller to enter an undefined state where normal operations cease to function correctly, resulting in a denial of service condition that can persist until manual intervention or system reboot occurs.
From an operational impact perspective, this vulnerability presents significant risks to industrial environments where these controllers are critical to process control and automation systems. The denial of service condition can lead to production halts, safety system failures, or complete loss of control over industrial processes. The vulnerability is particularly concerning because it affects multiple generations of Modicon controllers, suggesting a systemic flaw in the software design patterns used across these platforms. The attack vector through Modbus protocol makes this vulnerability accessible to adversaries who can potentially gain network access to the industrial control network and exploit this weakness without requiring physical access to the equipment.
The exploitation of this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the Execution and Persistence domains, as attackers can leverage Modbus communications to trigger the unhandled exception and maintain control over the compromised system. Organizations should consider implementing network segmentation and access controls to limit Modbus traffic to authorized systems only, while also applying vendor-provided firmware updates and patches as soon as they become available. The vulnerability underscores the importance of robust error handling and exception management in industrial control systems, particularly in environments where system availability directly correlates with operational safety and business continuity requirements.