CVE-2018-7853 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 denial of service when reading invalid physical memory blocks in the controller over Modbus
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Analysis
by VulDB Data Team • 09/23/2023
The vulnerability identified as CVE-2018-7853 represents a critical uncaught exception flaw classified under CWE-248 that affects several Siemens Modicon series controllers including the M580, M340, Quantum, and Premium models. This vulnerability manifests when these industrial control systems process Modbus requests attempting to read invalid physical memory blocks within the controller's memory space. The flaw stems from inadequate error handling mechanisms within the Modbus protocol implementation, specifically in how the controllers respond to malformed or unauthorized memory access requests. When such invalid memory block reads are attempted, the system fails to properly handle the exception condition, leading to system instability and potential service disruption.
The technical nature of this vulnerability allows malicious actors or unauthorized users to exploit the lack of proper exception handling by sending specially crafted Modbus requests designed to access memory locations that do not exist or are not accessible to the requesting entity. This type of attack can be executed through network-based communication channels where Modbus protocol is utilized for industrial control system communication. The controllers do not implement robust exception handling routines to catch and gracefully manage these invalid memory access attempts, causing the system to either crash or become unresponsive during the processing of such requests. This behavior aligns with the ATT&CK framework's concept of privilege escalation and denial of service through system resource manipulation.
The operational impact of this vulnerability extends beyond simple service disruption as it can compromise the availability and integrity of critical industrial processes. When the controller experiences a denial of service condition due to this uncaught exception, it can lead to complete system shutdown or partial operational failure, potentially affecting production lines, safety systems, or other critical infrastructure components that depend on these controllers. The vulnerability affects multiple generations of Siemens controllers, indicating a widespread issue within the industrial control system ecosystem. Organizations relying on these devices for critical operations face significant risk of operational disruption, especially in environments where continuous operation is essential for safety or production requirements. The vulnerability's impact is particularly concerning in critical infrastructure sectors such as power generation, water treatment, manufacturing, and other industrial environments where Modbus communication is prevalent.
Mitigation strategies for this vulnerability should focus on implementing proper exception handling mechanisms within the Modbus protocol implementation and ensuring that all memory access requests are properly validated before processing. Network segmentation and access control measures should be deployed to limit unauthorized access to Modbus communication channels, while regular firmware updates from Siemens should be applied to address the underlying exception handling issues. System monitoring should be enhanced to detect abnormal memory access patterns that may indicate exploitation attempts, and network intrusion detection systems should be configured to identify and alert on suspicious Modbus traffic patterns. Additionally, organizations should conduct thorough vulnerability assessments of their industrial control systems to identify other potential uncaught exception scenarios that may exist within their operational technology environments, as this vulnerability demonstrates the importance of robust error handling in industrial control systems.