CVE-2021-33486 in Runtime Toolkit for VxWorks
Summary
by MITRE • 08/03/2021
All versions of the CODESYS V3 Runtime Toolkit for VxWorks from version V3.5.8.0 and before version V3.5.17.10 have Improper Handling of Exceptional Conditions.
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Analysis
by VulDB Data Team • 08/07/2021
The vulnerability identified as CVE-2021-33486 affects the CODESYS V3 Runtime Toolkit for VxWorks, a critical component used in industrial automation and embedded systems environments. This issue manifests in all versions from V3.5.8.0 up to but not including V3.5.17.10, representing a significant security gap that could impact operational technology infrastructure. The vulnerability falls under the category of improper handling of exceptional conditions, which represents a fundamental flaw in how the system manages error states and abnormal execution paths. This type of vulnerability is particularly dangerous in industrial control systems where reliability and predictable behavior are paramount for safety and operational continuity.
The technical flaw in question involves the runtime toolkit's inadequate management of exceptional conditions that occur during program execution. When unexpected events or error states arise within the CODESYS environment running on VxWorks, the system fails to properly handle these exceptions, potentially leading to system instability, unexpected termination, or even allowing malicious actors to exploit the error handling mechanisms. This improper exception handling can result in denial of service conditions where legitimate operations are disrupted, or more severe scenarios where attackers might be able to manipulate the system's behavior through carefully crafted inputs that trigger these exceptional conditions. The vulnerability is classified under CWE-703, which specifically addresses improper handling of exceptional conditions in software systems.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the integrity of industrial control processes. In environments where CODESYS V3 Runtime Toolkit for VxWorks is deployed for critical infrastructure management, the improper exception handling could lead to cascading failures that affect production processes, safety systems, or monitoring capabilities. The vulnerability affects systems that rely on VxWorks operating system for real-time control applications, making it particularly concerning for industrial IoT deployments, manufacturing automation, and other embedded systems where the toolkit is used for runtime execution of control logic. Organizations implementing these systems may experience unexpected downtime, process disruptions, or potential data integrity issues that could have serious consequences in industrial settings.
Mitigation strategies for CVE-2021-33486 focus primarily on upgrading to the patched version V3.5.17.10 or later, which addresses the improper handling of exceptional conditions in the CODESYS Runtime Toolkit. Organizations should conduct thorough risk assessments to determine their exposure and implement network segmentation to limit access to affected systems. The vulnerability aligns with ATT&CK technique T1203, which involves exploitation of software vulnerabilities to gain unauthorized access or cause system disruption, making it a target for both accidental system failures and deliberate exploitation attempts. Security teams should also implement monitoring solutions to detect anomalous behavior patterns that might indicate exploitation attempts, while maintaining proper patch management procedures to ensure all industrial control systems remain up to date with security fixes. The remediation process requires careful planning due to the critical nature of industrial control systems, often necessitating coordinated testing and deployment schedules to minimize operational impact while addressing the security gap.