CVE-2021-40872 in uaToolkit Embedded
Summary
by MITRE • 11/11/2021
An issue was discovered in Softing Industrial Automation uaToolkit Embedded before 1.40. Remote attackers to cause a denial of service (DoS) or login as an anonymous user (bypassing security checks) by sending crafted messages to a OPC/UA server. The server process may crash unexpectedly because of an invalid type cast, and must be restarted.
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Analysis
by VulDB Data Team • 11/12/2021
The vulnerability identified as CVE-2021-40872 represents a critical security flaw in Softing Industrial Automation uaToolkit Embedded versions prior to 1.40. This issue manifests within the OPC/UA server implementation and affects industrial automation environments where secure communication protocols are essential for operational technology systems. The vulnerability stems from improper handling of incoming messages that can lead to either denial of service conditions or unauthorized access to the system. OPC/UA servers form the backbone of industrial communication systems, making this vulnerability particularly concerning for manufacturing, process control, and critical infrastructure environments. The affected software is commonly deployed in environments where continuous operation is paramount, and any disruption can lead to significant operational impacts.
The technical root cause of this vulnerability lies in an invalid type cast that occurs when processing crafted messages sent to the OPC/UA server. This type casting error represents a classic software flaw that can be categorized under CWE-704, which deals with incorrect type conversion or cast operations. When remote attackers send specifically crafted messages to the server, the system attempts to perform an invalid type conversion that results in unexpected behavior. The invalid type cast leads to memory corruption or execution flow disruption, causing the server process to crash and terminate unexpectedly. This crash condition directly maps to the denial of service attack vector described in the vulnerability, where legitimate users lose access to the industrial automation services. The vulnerability also enables an anonymous login bypass that allows attackers to circumvent normal authentication mechanisms, potentially leading to unauthorized access to sensitive industrial data and control functions.
The operational impact of CVE-2021-40872 extends beyond simple service disruption to encompass potential security breaches in industrial control systems. The ability to cause a denial of service means that critical manufacturing processes relying on OPC/UA communication can experience unexpected downtime, potentially leading to production losses, safety risks, and operational disruptions. When attackers can bypass authentication and gain anonymous access, they can potentially manipulate industrial processes, access sensitive operational data, or even cause physical damage to equipment through unauthorized control commands. The need for manual server restart following a crash represents an additional operational burden, as automated systems may not recover gracefully from such interruptions. This vulnerability particularly affects environments that depend on continuous operation and where the industrial internet of things (IIoT) infrastructure requires robust security controls to prevent unauthorized access to critical systems.
Mitigation strategies for this vulnerability require immediate patching of affected systems to version 1.40 or later of the Softing uaToolkit Embedded software. Organizations should implement network segmentation and access controls to limit exposure of OPC/UA servers to untrusted networks, following the principle of least privilege as outlined in various cybersecurity frameworks including NIST SP 800-53. Network monitoring should be enhanced to detect unusual patterns of communication that may indicate exploitation attempts, and intrusion detection systems should be configured to alert on suspicious OPC/UA traffic patterns. The vulnerability also highlights the importance of secure coding practices and proper input validation, as the issue stems from inadequate message handling and type conversion checks. Organizations should conduct comprehensive vulnerability assessments of their industrial control systems to identify other potential instances of similar flaws, and implement regular security testing procedures to prevent similar issues from arising in the future. The ATT&CK framework categorizes this vulnerability under the T1190 technique for Exploit Public-Facing Application, and potentially under T1078 for Valid Accounts, as the anonymous access bypass allows for persistence and privilege escalation within industrial environments.