CVE-2018-7844 in Modicon M580
Summary
by MITRE
A CWE-200: Information Exposure vulnerability exists in all versions of the Modicon M580, Modicon M340, Modicon Quantum, and Modicon Premium which could cause the disclosure of SNMP information when reading memory blocks from the controller over Modbus.
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Analysis
by VulDB Data Team • 09/23/2023
The vulnerability identified as CVE-2018-7844 represents a significant information exposure risk within several generations of Schneider Electric Modicon controllers, specifically affecting the M580, M340, Quantum, and Premium series. This weakness falls under CWE-200, which categorizes information exposure vulnerabilities where sensitive data becomes accessible to unauthorized parties. The affected devices operate within industrial control systems and supervisory control and data acquisition environments where security is paramount for operational integrity and safety.
The technical flaw manifests when these controllers process memory block read requests over the Modbus protocol, which is commonly used for communication between industrial devices and supervisory systems. During these read operations, the system inadvertently exposes SNMP (Simple Network Management Protocol) information that should remain protected within the controller's memory. This exposure occurs because the Modbus implementation fails to properly sanitize or restrict access to memory regions that contain SNMP configuration data, credentials, or other sensitive management information. The vulnerability is particularly concerning because Modbus is widely deployed in industrial environments and often operates without adequate network segmentation or authentication layers.
The operational impact of this vulnerability extends beyond simple information disclosure, as the exposed SNMP data could enable attackers to gain deeper insights into the industrial control system architecture. An attacker who successfully exploits this vulnerability could obtain SNMP community strings, device configurations, network topology information, and potentially credentials that would allow further exploitation of the industrial network. This exposure creates opportunities for lateral movement within the industrial control system, potentially leading to more severe consequences including system disruption, data manipulation, or even physical damage to industrial processes. The vulnerability affects all versions of the impacted controllers, indicating it represents a fundamental design flaw rather than a specific patchable issue.
Organizations operating these affected controllers should implement immediate mitigations including network segmentation to isolate industrial control systems from general IT networks, implementing strict access controls and authentication mechanisms for Modbus communications, and monitoring for unauthorized memory read attempts. The vulnerability aligns with ATT&CK technique T1046, Network Service Scanning, as attackers could use this weakness to discover network services and gather intelligence about the industrial control environment. Additionally, this issue demonstrates the importance of following industrial cybersecurity frameworks such as NIST SP 800-82 and IEC 62443, which emphasize the need for secure network design and proper access controls in industrial environments. Regular security assessments and firmware updates should be implemented to address such vulnerabilities, though the widespread nature of this flaw across multiple controller generations suggests that comprehensive system redesign or replacement may be necessary in some cases.