CVE-2021-29239 in Development System
Summary
by MITRE • 05/04/2021
CODESYS Development System 3 before 3.5.17.0 displays or executes malicious documents or files embedded in libraries without first checking their validity.
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Analysis
by VulDB Data Team • 05/07/2021
The vulnerability identified as CVE-2021-29239 affects the CODESYS Development System version 3 prior to 3.5.17.0, representing a critical security flaw in industrial automation software that could enable remote code execution through malicious document embedding. This issue stems from inadequate input validation and sanitization mechanisms within the library handling functionality of the software development environment. The vulnerability creates a dangerous condition where the system automatically processes and executes content without performing proper validation checks on the embedded documents or files, effectively bypassing security controls that should prevent unauthorized code execution.
The technical implementation of this vulnerability involves the software's failure to perform proper file type verification and content inspection when processing library files that may contain embedded malicious payloads. This weakness allows attackers to craft specially formatted library files containing malicious code that gets executed during normal software operations. The flaw operates at the application level and specifically impacts the library import and processing mechanisms, where the system assumes all content within library files is legitimate without performing cryptographic verification or content analysis. This behavior aligns with CWE-20, which describes improper input validation, and represents a classic example of insufficient sanitization of user-supplied data.
The operational impact of this vulnerability is particularly severe in industrial control systems and automation environments where CODESYS is commonly deployed. Attackers could leverage this vulnerability to execute arbitrary code on systems running vulnerable versions of the development environment, potentially leading to complete system compromise and disruption of industrial processes. The vulnerability affects not only the development workstation but could also enable lateral movement within networked industrial environments where such development systems might be connected to production networks. This represents a significant risk to operational technology infrastructure and could enable attackers to gain persistent access to critical industrial control systems. The vulnerability's exploitation could result in data corruption, system downtime, and potential safety hazards in environments where automation systems control physical processes.
Mitigation strategies for this vulnerability should focus on immediate remediation through the installation of CODESYS Development System version 3.5.17.0 or later, which includes proper input validation and sanitization mechanisms. Organizations should also implement network segmentation to isolate development environments from critical production systems, employ application whitelisting policies to restrict execution of unauthorized code, and conduct regular security assessments of industrial automation environments. Additional defensive measures include implementing file integrity monitoring for library files, deploying network intrusion detection systems to monitor for suspicious file transfer activities, and establishing secure development practices that include code review and validation of all third-party libraries. The vulnerability demonstrates the importance of input validation in industrial software environments and aligns with ATT&CK technique T1059.001 for command and script interpreter execution, highlighting the need for comprehensive security controls in operational technology environments. Organizations should also consider implementing zero-trust network architectures and regular security training for development personnel to prevent similar vulnerabilities from being introduced through insecure coding practices.