CVE-2021-42577 in OPC UA C++ SDK
Summary
by MITRE • 03/12/2022
An issue was discovered in Softing OPC UA C++ SDK before 5.70. A malformed OPC/UA message abort packet makes the client crash with a NULL pointer dereference.
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Analysis
by VulDB Data Team • 03/14/2022
The vulnerability identified as CVE-2021-42577 represents a critical null pointer dereference flaw within the Softing OPC UA C++ SDK version 5.69 and earlier. This issue manifests when a malformed OPC/UA message abort packet is processed by the client application, leading to an unexpected system crash. The vulnerability stems from inadequate input validation mechanisms within the SDK's message handling routines, specifically in how abort packets are parsed and interpreted. The OPC UA protocol, which is fundamental to industrial automation and IoT communications, relies heavily on proper message handling to maintain system stability and security. When a client encounters such malformed packets, the SDK fails to properly validate the packet structure before attempting to dereference pointers, resulting in a segmentation fault or access violation.
The technical nature of this vulnerability places it squarely within CWE-476, which defines NULL pointer dereference as a condition where a null value is dereferenced, causing program termination. This flaw operates at the application layer of the OPC UA communication stack, specifically affecting the client-side processing of abort messages. The attack vector is straightforward yet potentially impactful, as an attacker could send a specially crafted abort packet to any vulnerable client system, causing immediate service disruption. The vulnerability's impact is particularly severe in industrial control systems where OPC UA is extensively deployed for real-time data exchange between devices and supervisory systems. The crash occurs during message processing rather than during initialization, making it difficult to detect through standard application monitoring tools and potentially allowing for denial of service attacks that could compromise operational continuity.
The operational implications of CVE-2021-42577 extend beyond simple service disruption to potentially threaten industrial control system integrity. In environments where OPC UA clients are critical for process control, such as manufacturing plants, energy grids, or water treatment facilities, a client crash could lead to cascading failures or require manual intervention to restore system functionality. The vulnerability affects systems that rely on Softing's OPC UA C++ SDK for their communication infrastructure, which includes numerous industrial automation platforms. This flaw aligns with ATT&CK technique T1499.004, which covers network disruption attacks through service availability, as the null pointer dereference effectively renders the client application unavailable. Organizations using affected versions of the SDK should implement immediate patching strategies, as the vulnerability does not require authentication or special privileges to exploit. The remediation process involves upgrading to Softing OPC UA C++ SDK version 5.70 or later, which includes proper input validation and error handling for abort packet processing. Additionally, network segmentation and monitoring should be enhanced to detect and prevent the transmission of malformed OPC/UA packets that could trigger this vulnerability, as the attack can be executed remotely without requiring physical access to the target system.