CVE-2020-5658 in MELSEC iQ-R
Summary
by MITRE • 11/03/2020
Resource Management Errors vulnerability in TCP/IP function included in the firmware of MELSEC iQ-R series (RJ71EIP91 EtherNet/IP Network Interface Module First 2 digits of serial number are '02' or before, RJ71PN92 PROFINET IO Controller Module First 2 digits of serial number are '01' or before, RD81DL96 High Speed Data Logger Module First 2 digits of serial number are '08' or before, RD81MES96N MES Interface Module First 2 digits of serial number are '04' or before, and RD81OPC96 OPC UA Server Module First 2 digits of serial number are '04' or before) allows a remote unauthenticated attacker to stop the network functions of the products via a specially crafted packet.
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Analysis
by VulDB Data Team • 12/01/2020
This vulnerability represents a critical resource management error within the TCP/IP stack implementation of Mitsubishi Electric's MELSEC iQ-R series industrial control systems. The flaw affects multiple modules including EtherNet/IP Network Interface Modules, PROFINET IO Controller Modules, High Speed Data Logger Modules, MES Interface Modules, and OPC UA Server Modules. The vulnerability stems from inadequate handling of network packets that can trigger resource exhaustion or improper state management within the embedded firmware, specifically impacting systems where the first two digits of the serial number fall within specified ranges. This represents a fundamental flaw in the network protocol processing logic that fails to properly validate incoming packet structures and resource allocation mechanisms.
The technical exploitation of this vulnerability occurs through the transmission of specially crafted network packets that cause the affected industrial devices to cease normal network operations. The attack vector is entirely remote and requires no authentication credentials, making it particularly dangerous in industrial environments where network connectivity is essential for operational continuity. The resource management error likely involves improper handling of TCP connection states, buffer management, or network socket allocation that becomes exhausted or corrupted when processing malformed packets. According to CWE classification, this vulnerability maps to CWE-400: Uncontrolled Resource Consumption, which encompasses various forms of resource exhaustion attacks that can lead to denial of service conditions. The flaw demonstrates poor input validation and resource management practices within the embedded TCP/IP stack implementation.
The operational impact of this vulnerability extends beyond simple network disruption to potentially compromise entire industrial control processes. When network functions are stopped, critical communication channels between programmable logic controllers, human machine interfaces, and other industrial equipment become unavailable, leading to production halts, data loss, and potential safety hazards in manufacturing environments. The affected modules serve as essential communication bridges in industrial networks, and their failure can cascade through entire production lines. From an ATT&CK framework perspective, this vulnerability enables the T1499.004 technique of Network Denial of Service, allowing adversaries to disrupt industrial operations without requiring physical access or elevated privileges. The remote nature of the attack means that threat actors can exploit this weakness from anywhere on the network, making it particularly concerning for industrial environments that may have limited network segmentation.
Mitigation strategies should focus on immediate network isolation of affected devices until firmware updates are deployed, implementing network monitoring to detect anomalous packet patterns, and establishing robust network segmentation policies. Organizations should prioritize firmware updates from Mitsubishi Electric that address the specific resource management flaws in the TCP/IP implementation. Network administrators should consider implementing intrusion detection systems that can identify malformed packets targeting these specific vulnerabilities, and establish baseline network behavior monitoring to quickly detect service disruptions. The vulnerability highlights the critical need for secure embedded system design in industrial control environments, emphasizing proper resource management, input validation, and robust error handling mechanisms. Regular vulnerability assessments of industrial control systems should include specific checks for similar resource management errors in network protocol implementations, particularly in legacy industrial equipment where firmware updates may be challenging to deploy across large installations.