CVE-2015-5374 in EN100 Module
Summary
by MITRE
The EN100 module with firmware before 4.25 for Siemens SIPROTEC 4 and SIPROTEC Compact devices allows remote attackers to cause a denial of service via crafted packets on UDP port 50000.
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Analysis
by VulDB Data Team • 06/30/2024
The vulnerability identified as CVE-2015-5374 affects Siemens SIPROTEC 4 and SIPROTEC Compact protective relays running EN100 module firmware versions prior to 4.25. These industrial control devices are critical components in power systems, providing protection and control functions for electrical infrastructure including substations and power generation facilities. The affected devices operate within the industrial control systems (ICS) domain where reliability and availability are paramount for maintaining power grid stability and safety. The vulnerability specifically resides in the network communication stack of these protective relays, which are designed to monitor and protect electrical equipment from faults and abnormal operating conditions.
The technical flaw manifests in the processing of UDP packets received on port 50000, which serves as the communication channel for the EN100 module. Remote attackers can exploit this vulnerability by crafting specially formatted packets that trigger a buffer overflow or memory corruption condition within the device's firmware. When the device receives these malformed packets, the insufficient input validation and lack of proper bounds checking in the network processing routine cause the system to crash or become unresponsive. This type of vulnerability falls under CWE-129, which describes improper validation of array indices, and represents a classic example of an uncontrolled buffer access condition that can lead to denial of service scenarios. The vulnerability demonstrates poor defensive programming practices where the system fails to properly sanitize incoming network data before processing it.
The operational impact of this vulnerability is severe for industrial environments where these protective relays operate. A successful exploitation can result in complete denial of service for the affected device, potentially leading to loss of protection functions for critical electrical equipment. In power grid applications, this could mean that protective relays fail to detect and respond to electrical faults, creating cascading failures that might affect large areas of electrical supply. The remote nature of the attack means that adversaries do not require physical access to the devices, making the vulnerability particularly dangerous in environments where physical security controls may be inadequate. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks targeting industrial control systems, and represents a significant risk to operational technology infrastructure.
Organizations should implement immediate mitigation strategies including firmware updates to version 4.25 or later, which contain the necessary patches to address the buffer overflow condition. Network segmentation and access controls should be enforced to limit exposure of these devices to untrusted networks, while monitoring systems should be deployed to detect anomalous packet patterns on UDP port 50000. Additionally, network administrators should consider implementing firewall rules that restrict access to port 50000 to only trusted sources and establish baseline network behavior for normal packet traffic to facilitate early detection of potential exploitation attempts. The vulnerability highlights the importance of maintaining current firmware versions in industrial control systems and demonstrates the critical need for security updates in operational technology environments where system availability is essential for safety and operational continuity.