CVE-2018-11451 in EN100 Ethernet Module
Summary
by MITRE
A vulnerability has been identified in Firmware variant IEC 61850 for EN100 Ethernet module (All versions < V4.33), Firmware variant PROFINET IO for EN100 Ethernet module (All versions), Firmware variant Modbus TCP for EN100 Ethernet module (All versions), Firmware variant DNP3 TCP for EN100 Ethernet module (All versions), Firmware variant IEC104 for EN100 Ethernet module (All versions), SIPROTEC 5 relays with CPU variants CP300 and CP100 and the respective Ethernet communication modules (All versions < V7.80), SIPROTEC 5 relays with CPU variants CP200 and the respective Ethernet communication modules (All versions). Specially crafted packets to port 102/tcp could cause a denial-of-service condition in the affected products. A manual restart is required to recover the EN100 module functionality of SIPROTEC 4 and SIPROTEC Compact relays. Successful exploitation requires an attacker with network access to send multiple packets to the affected products or modules. As a precondition the IEC 61850-MMS communication needs to be activated on the affected products or modules. No user interaction or privileges are required to exploit the vulnerability. The vulnerability could allow causing a Denial-of-Service condition of the network functionality of the device, compromising the availability of the system. At the time of advisory publication no public exploitation of this security vulnerability was known.
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Analysis
by VulDB Data Team • 04/25/2023
This vulnerability affects industrial control systems and protection relays manufactured by Siemens, specifically targeting their EN100 Ethernet modules and SIPROTEC 5 relays. The issue stems from improper handling of specially crafted packets sent to port 102/tcp which is used for IEC 61850 MMS (Manufacturing Message Specification) communication. The vulnerability exists across multiple firmware variants including IEC 61850, PROFINET IO, Modbus TCP, DNP3 TCP, and IEC104 protocols, indicating a systemic flaw in the network protocol handling mechanisms of these industrial devices. According to CWE-400, this represents an input validation vulnerability where the system fails to properly validate incoming network traffic, leading to resource exhaustion or system instability. The attack vector requires only network access and does not necessitate user interaction or elevated privileges, making it particularly dangerous in operational technology environments where physical and network security boundaries may be less strictly enforced.
The technical flaw manifests when the affected devices receive malformed packets on port 102/tcp, which triggers an abnormal termination of the MMS communication process. This results in a denial-of-service condition that renders the Ethernet communication module non-functional, requiring manual restart to restore normal operation. The vulnerability impacts both SIPROTEC 4 and SIPROTEC Compact relays, with specific firmware versions below V4.33 for IEC 61850 and below V7.80 for CP300/CP100 CPU variants. The condition affects the availability aspect of the CIA triad, potentially disrupting critical industrial processes that depend on these protection relays. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing) as it represents a network-based denial-of-service attack that can be initiated without user interaction. The precondition that IEC 61850-MMS communication must be activated means that organizations with properly configured security measures that disable unnecessary protocols may be less vulnerable, though this is not a reliable defense mechanism.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the integrity of industrial control systems. When protection relays become unavailable, the entire protection scheme for critical infrastructure components may be compromised, leading to cascading failures in power systems or other industrial processes. The requirement for manual restart indicates that automated recovery mechanisms are insufficient, potentially leading to extended downtime during critical operations. Organizations using these devices face significant risk in environments where continuous operation is essential, such as power generation, oil and gas processing, or water treatment facilities. The vulnerability affects devices that are typically deployed in secure industrial environments but may still be accessible to attackers through network connections or compromised adjacent systems. Given the industrial nature of these devices, the potential for physical damage or safety incidents increases when the protection systems become unavailable due to this denial-of-service condition. The lack of public exploitation at the time of advisory publication does not diminish the severity, as such vulnerabilities often represent a significant risk to operational continuity and safety-critical systems.
Mitigation strategies should focus on network segmentation and access controls to prevent unauthorized network access to affected devices. Organizations should implement firewall rules to block incoming traffic on port 102/tcp except from authorized management systems, and disable unnecessary communication protocols to reduce the attack surface. Regular firmware updates should be implemented immediately upon availability of patches from Siemens, with particular attention to the version requirements specified in the advisory. Network monitoring should be enhanced to detect unusual traffic patterns on port 102/tcp that could indicate exploitation attempts. Device configuration reviews should ensure that IEC 61850-MMS communication is only enabled when absolutely necessary, and that proper authentication mechanisms are in place. The vulnerability also highlights the need for robust incident response procedures that include manual recovery processes for industrial control systems, as automated recovery may not be sufficient for these specialized devices. Organizations should also consider implementing network access control lists and intrusion detection systems specifically configured to monitor for this type of denial-of-service attack pattern.