CVE-2021-20987 in EtherNet-IP Core
Summary
by MITRE • 02/16/2021
A denial of service and memory corruption vulnerability was found in Hilscher EtherNet/IP Core V2 prior to V2.13.0.21that may lead to code injection through network or make devices crash without recovery.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/02/2021
The vulnerability identified as CVE-2021-20987 represents a critical security flaw within the Hilscher EtherNet/IP Core V2 software component that affects versions prior to V2.13.0.21. This issue manifests as a combination of denial of service conditions and memory corruption that can potentially enable remote code execution capabilities. The vulnerability resides in the network protocol implementation of the EtherNet/IP core, which is widely used in industrial automation and control systems for communication between devices and control systems. The flaw specifically impacts devices that rely on Hilscher's EtherNet/IP implementation for their network operations, creating a significant risk for industrial control systems that depend on stable network communication.
The technical root cause of this vulnerability stems from improper input validation and memory handling within the EtherNet/IP protocol stack implementation. When processing network packets or specific protocol messages, the software fails to properly validate incoming data structures, leading to memory corruption conditions that can be exploited by malicious actors. This memory corruption can manifest in various ways including buffer overflows, use-after-free conditions, or other memory management errors that occur during packet processing. The vulnerability allows attackers to craft specially malformed network packets that, when processed by the affected software, trigger the memory corruption and subsequent denial of service conditions. According to CWE classification, this vulnerability aligns with CWE-121, heap-based buffer overflow, and CWE-125, out-of-bounds read, which are common categories for memory corruption vulnerabilities in network protocol implementations.
The operational impact of CVE-2021-20987 extends beyond simple service disruption to potentially enable complete system compromise through remote code execution capabilities. When exploited, the vulnerability can cause devices to crash and become unrecoverable, leading to significant operational downtime in industrial environments where continuous operation is critical. The denial of service aspect can result in complete loss of network connectivity for affected devices, while the memory corruption component provides a potential pathway for attackers to execute arbitrary code on the target systems. This vulnerability is particularly concerning in industrial control environments where network reliability is paramount, as it can affect critical infrastructure such as manufacturing systems, power grid controls, and other industrial automation networks. The attack surface is broad as the vulnerability affects any device running the vulnerable version of Hilscher EtherNet/IP Core V2, including programmable logic controllers, remote terminal units, and other industrial network equipment.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and patches provided by Hilscher to address the memory corruption and input validation issues. Organizations should prioritize updating their affected systems to version V2.13.0.21 or later, which contains the necessary fixes for the identified vulnerabilities. Network segmentation and access controls should be implemented to limit exposure of vulnerable devices to untrusted networks, following the principle of least privilege and network isolation practices recommended by NIST SP 800-53. Additionally, implementing network monitoring and intrusion detection systems can help identify exploitation attempts through anomalous network traffic patterns that may indicate attempted exploitation of this vulnerability. The ATT&CK framework categorizes this type of vulnerability under T1203, Exploitation for Client Execution, and T1499, Endpoint Termination, as it enables both remote code execution and system termination capabilities. Organizations should also conduct thorough vulnerability assessments to identify all instances of the affected software within their networks and implement proper security monitoring to detect potential exploitation attempts.