CVE-2020-7054 in libIEC61850
Summary
by MITRE
MmsValue_decodeMmsData in mms/iso_mms/server/mms_access_result.c in libIEC61850 through 1.4.0 has a heap-based buffer overflow when parsing the MMS_BIT_STRING data type.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 03/21/2024
The vulnerability identified as CVE-2020-7054 represents a critical heap-based buffer overflow within the libIEC61850 library version 1.4.0 and earlier. This flaw exists in the MmsValue_decodeMmsData function located in the mms/iso_mms/server/mms_access_result.c file, specifically when processing MMS_BIT_STRING data types. The issue arises from insufficient input validation and boundary checking during the parsing of binary data structures, creating a scenario where maliciously crafted MMS_BIT_STRING data can cause the application to write beyond allocated memory boundaries.
The technical implementation of this vulnerability stems from improper handling of variable-length bit string data within the IEC 61850 communication protocol stack. When the MmsValue_decodeMmsData function processes incoming MMS_BIT_STRING data, it fails to properly validate the length field against the actual buffer size, allowing attackers to specify a length that exceeds the allocated memory space. This condition creates a classic heap overflow vulnerability that can be exploited to overwrite adjacent memory locations, potentially leading to arbitrary code execution or denial of service conditions. The vulnerability aligns with CWE-121 heap-based buffer overflow classification and represents a significant concern for industrial control systems that rely on IEC 61850 protocols for communication.
The operational impact of CVE-2020-7054 extends beyond simple memory corruption, as it affects systems implementing IEC 61850 standards including smart grid infrastructure, substation automation systems, and industrial control networks. Attackers exploiting this vulnerability could gain unauthorized access to critical infrastructure components, manipulate control signals, or cause system disruptions that compromise the integrity and availability of industrial processes. The vulnerability is particularly concerning in environments where IEC 61850 servers are exposed to untrusted network traffic, as it could enable remote code execution without authentication requirements. This scenario aligns with ATT&CK technique T1203 for legitimate credentials and T1059 for command and scripting interpreter, potentially allowing attackers to establish persistent access to industrial control systems.
Mitigation strategies for CVE-2020-7054 should prioritize immediate patching of affected libIEC61850 installations to version 1.4.1 or later, which contains the necessary memory boundary checks and input validation. Network segmentation and access controls should be implemented to limit exposure of IEC 61850 servers to untrusted networks, while monitoring systems should be configured to detect anomalous MMS_BIT_STRING data patterns. Additionally, implementing proper input sanitization and boundary checking mechanisms within custom applications that utilize libIEC61850 can provide additional defense-in-depth layers. Organizations should also conduct comprehensive vulnerability assessments of their industrial control systems to identify other potential entry points and ensure proper network architecture design that minimizes the attack surface for such critical infrastructure vulnerabilities.