CVE-2021-31630 in Webserver
Summary
by MITRE • 08/03/2021
Command Injection in Open PLC Webserver v3 allows remote attackers to execute arbitrary code via the "Hardware Layer Code Box" component on the "/hardware" page of the application.
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Analysis
by VulDB Data Team • 08/07/2021
The vulnerability identified as CVE-2021-31630 represents a critical command injection flaw within the Open PLC Webserver version 3, a web-based interface designed for programmable logic controller configuration and management. This vulnerability exists within the "Hardware Layer Code Box" component accessible through the "/hardware" page of the web application, creating a significant security risk for industrial control systems that rely on this platform for operational technology infrastructure management.
The technical exploitation of this vulnerability occurs through improper input validation and sanitization within the web server's hardware configuration interface. When users provide input to the "Hardware Layer Code Box" component, the application fails to adequately sanitize or escape command characters and special sequences that could be interpreted by the underlying operating system. This allows remote attackers to inject malicious commands that are subsequently executed with the privileges of the web server process, typically running with elevated system permissions. The flaw manifests as a direct injection point where attacker-controlled input bypasses all security controls and directly interfaces with the command execution layer of the web server.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the affected system. Successful exploitation enables adversaries to execute arbitrary commands on the target machine, potentially leading to full system compromise, data exfiltration, or disruption of industrial processes. Industrial control systems that depend on Open PLC Webserver for their operational technology infrastructure become particularly vulnerable, as attackers could manipulate hardware configurations, modify control logic, or gain unauthorized access to critical manufacturing processes. The remote nature of the attack means that threat actors can exploit this vulnerability from anywhere on the network without requiring physical access to the industrial equipment.
This vulnerability aligns with CWE-77 and CWE-94 categories within the Common Weakness Enumeration framework, specifically addressing command injection and code injection weaknesses that have been consistently identified as critical threats in industrial control systems. The attack pattern corresponds to techniques documented in the MITRE ATT&CK framework under the T1059.001 sub-technique for Command and Scripting Interpreter, where adversaries leverage web application interfaces to execute malicious commands. Organizations implementing this web server for industrial automation should consider the broader implications of command injection vulnerabilities in operational technology environments, where the consequences of exploitation can extend beyond traditional information technology concerns to affect physical system integrity and safety.
Mitigation strategies for CVE-2021-31630 should prioritize immediate patching of the Open PLC Webserver to the latest version that addresses this command injection vulnerability. Network segmentation and access controls should be implemented to limit exposure of the web interface to trusted networks only, while disabling unnecessary administrative functions. Input validation and sanitization measures must be strengthened throughout the application to prevent command injection attempts, and all user inputs should be properly escaped and validated before processing. Additionally, organizations should implement monitoring solutions to detect anomalous command execution patterns and establish incident response procedures specifically tailored to industrial control system security breaches. Regular security assessments of operational technology environments are essential to identify similar vulnerabilities that could compromise the integrity of critical infrastructure systems.