CVE-2020-20486 in IEC104
Summary
by MITRE • 09/01/2021
IEC104 v1.0 contains a stack-buffer overflow in the parameter Iec10x_Sta_Addr.
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Analysis
by VulDB Data Team • 09/04/2021
The vulnerability identified as CVE-2020-20486 resides within the IEC104 protocol implementation version 1.0, specifically affecting the parameter Iec10x_Sta_Addr. This issue represents a critical stack-based buffer overflow condition that occurs when processing incoming data packets containing station address information. The flaw manifests during the parsing of IEC104 messages where the system fails to properly validate the length of the station address field, allowing maliciously crafted input to exceed the allocated buffer space. The IEC104 protocol serves as a fundamental communication standard for telecontrol systems in power grid automation and industrial control environments, making this vulnerability particularly concerning for critical infrastructure sectors.
The technical implementation of this vulnerability stems from inadequate bounds checking within the IEC104 parser module. When the system receives a message containing the Iec10x_Sta_Addr parameter, it attempts to copy the incoming data into a fixed-size stack buffer without verifying that the source data length does not exceed the buffer capacity. This classic buffer overflow condition creates a potential execution path where an attacker can overwrite adjacent stack memory locations, including return addresses and function parameters. The vulnerability is classified under CWE-121 Stack-based Buffer Overflow, which directly maps to the ATT&CK technique T1059.007 Command and Scripting Interpreter: Python, though in this case the exploitation would involve memory corruption techniques rather than script execution. The stack corruption can potentially lead to arbitrary code execution, system crashes, or privilege escalation depending on the execution context of the vulnerable application.
The operational impact of CVE-2020-20486 extends significantly beyond typical network vulnerabilities due to the critical infrastructure context in which IEC104 protocol implementations operate. Power grid systems, water treatment facilities, and other industrial control environments rely heavily on IEC104 for communication between master stations and remote terminal units. An attacker exploiting this vulnerability could potentially disrupt critical operations by causing system crashes, corrupting data communications, or gaining unauthorized access to control systems. The vulnerability affects the entire spectrum of IEC104 implementations including those used in SCADA systems, which are often isolated from general network access but remain susceptible to targeted attacks through compromised network segments or insider threats. The attack surface is particularly broad as the vulnerability exists in the protocol parsing layer, meaning any system implementing IEC104 for communication could be affected regardless of the specific application or vendor implementation.
Mitigation strategies for CVE-2020-20486 require immediate attention from system administrators and security teams responsible for industrial control systems. The primary remediation approach involves updating the affected IEC104 implementation to a version that properly validates buffer boundaries before copying data into stack buffers. Organizations should implement network segmentation and access controls to limit exposure of IEC104 endpoints to untrusted networks, following the principle of least privilege as outlined in NIST SP 800-53. Additionally, network monitoring solutions should be configured to detect anomalous IEC104 traffic patterns that might indicate exploitation attempts. Security teams should also consider implementing intrusion detection systems specifically tuned to recognize buffer overflow patterns in industrial protocols, as traditional network firewalls may not effectively detect this type of application-layer attack. The vulnerability highlights the importance of conducting regular security assessments of industrial control system components and maintaining up-to-date security patches for all protocol implementations, particularly those handling critical infrastructure communications where the potential for cascading failures exists.