CVE-2021-20836 in CX-Supervisor
Summary
by MITRE • 10/19/2021
Out-of-bounds read vulnerability in CX-Supervisor v4.0.0.13 and v4.0.0.16 allows an attacker with administrative privileges to cause information disclosure and/or arbitrary code execution by opening a specially crafted SCS project files.
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Analysis
by VulDB Data Team • 10/22/2021
The vulnerability CVE-2021-20836 represents a critical out-of-bounds read flaw in CX-Supervisor version 4.0.0.13 and 4.0.0.16, which falls under the Common Weakness Enumeration category CWE-125 - Out-of-bounds Read. This vulnerability specifically affects the handling of SCS project files within the supervisor software, creating a pathway for attackers to exploit the system through crafted file inputs. The flaw exists in the file parsing mechanism where the application fails to properly validate the boundaries of memory access when processing structured project files, leading to potential memory corruption issues.
The technical implementation of this vulnerability occurs when the CX-Supervisor application processes specially crafted SCS project files that contain malformed data structures. When the application attempts to read memory locations beyond the allocated buffer boundaries, it can access unauthorized memory regions that may contain sensitive information or executable code. This out-of-bounds memory access can result in information disclosure, where attackers can extract confidential data from memory, or potentially lead to arbitrary code execution if the attacker can control the memory content being accessed. The vulnerability is particularly dangerous because it requires only administrative privileges to exploit, which are often already available in many industrial control environments.
The operational impact of CVE-2021-20836 extends beyond simple information disclosure, as it represents a significant risk to industrial control systems and supervisory control environments. The vulnerability can be leveraged by attackers to gain unauthorized access to sensitive operational data, potentially compromising the integrity of control systems that manage critical infrastructure. In environments where CX-Supervisor is used for process control, this could lead to disruption of operations, data manipulation, or even physical safety risks. The attack vector is particularly concerning because it can be executed through file manipulation, making it difficult to detect and prevent through traditional network monitoring approaches.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: Python, as attackers may use the arbitrary code execution capability to deploy malicious payloads or establish persistence within the system. The vulnerability also maps to ATT&CK tactic TA0006 - Credential Access, as the information disclosure aspect can reveal system credentials or operational parameters. Organizations implementing industrial control systems should consider this vulnerability as part of their risk assessment for operational technology environments, particularly in sectors such as manufacturing, energy, and critical infrastructure where CX-Supervisor is commonly deployed. The vulnerability demonstrates the importance of input validation and memory safety practices in industrial software, and highlights the need for regular security updates and patch management in operational technology environments.
Mitigation strategies should focus on immediate patching of affected versions, implementation of strict file validation procedures, and network segmentation to limit access to administrative functions. Organizations should also implement monitoring for suspicious file access patterns and consider deploying intrusion detection systems specifically tuned to detect exploitation attempts targeting industrial control system vulnerabilities. The vulnerability underscores the necessity of applying security best practices to industrial control software, including proper memory management, input validation, and regular security assessments of operational technology environments.