CVE-2019-6806 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 variables in the controller using Modbus.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/23/2023
The vulnerability identified as CVE-2019-6806 represents a critical information exposure flaw affecting several generations of Schneider Electric Modicon controllers including the M580, M340, Quantum, and Premium series. This vulnerability falls under CWE-200, which specifically addresses information exposure weaknesses in software systems. The flaw manifests when these industrial control systems process Modbus requests to read variables from the controller, inadvertently disclosing sensitive Simple Network Management Protocol SNMP information that should remain protected within the system architecture. The vulnerability impacts the fundamental security posture of these industrial control devices, potentially exposing configuration details, system parameters, and operational data that adversaries could leverage for further exploitation.
The technical implementation of this vulnerability stems from insufficient access controls and information filtering mechanisms within the Modbus protocol handler of these controller models. When legitimate or malicious Modbus read requests are processed, the system fails to properly sanitize or restrict the data returned to the requesting entity, allowing SNMP-related metadata to be transmitted alongside the requested variable values. This occurs because the controller's response handling logic does not adequately differentiate between different types of information requests, creating an information leak channel that bypasses normal security boundaries. The vulnerability is particularly concerning as it operates at the protocol level, making it difficult to detect through standard network monitoring and potentially exploitable by attackers with minimal privileges.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked SNMP information could provide attackers with detailed insights into the controller's configuration, network topology, and operational parameters. This intelligence could enable more sophisticated attacks including privilege escalation, system compromise, or targeted disruption of industrial processes. The vulnerability affects critical infrastructure environments where these controllers are deployed, potentially exposing operational technology systems to unauthorized access and manipulation. Organizations relying on these controllers for industrial automation, process control, or manufacturing operations face significant risk if this vulnerability remains unaddressed, as the disclosed information could facilitate lateral movement within network segments or provide the foundation for more advanced persistent threats.
Mitigation strategies for CVE-2019-6806 should focus on implementing network segmentation and access control measures to limit Modbus and SNMP communication to authorized systems only. Organizations should deploy network monitoring solutions capable of detecting anomalous Modbus traffic patterns and implement proper firewall rules to restrict access to these industrial controllers. The affected Schneider Electric controllers require firmware updates from the vendor to address the underlying information exposure flaw, though organizations should also consider implementing network intrusion detection systems and conducting regular security assessments of their industrial control environments. This vulnerability aligns with ATT&CK technique T1046, Network Service Scanning, and T1082, System Information Discovery, as attackers could use the disclosed information to map network services and gather system details for further exploitation attempts.