CVE-2020-27274 in OPC UA Tunneller
Summary
by MITRE • 01/26/2021
Some parsing functions in the affected product do not check the return value of malloc and the thread handling the message is forced to close, which may lead to a denial-of-service condition on the OPC UA Tunneller (versions prior to 6.3.0.8233).
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Analysis
by VulDB Data Team • 02/20/2021
The vulnerability identified as CVE-2020-27274 affects the OPC UA Tunneller component within a specific software product, representing a critical denial-of-service weakness that stems from improper memory allocation handling. This issue resides in the parsing functions that process incoming messages, where the software fails to validate whether memory allocation operations succeed before proceeding with subsequent processing. The affected product versions prior to 6.3.0.8233 demonstrate a fundamental flaw in error handling mechanisms that can be exploited to disrupt service availability.
The technical root cause of this vulnerability can be categorized under CWE-703, which addresses improper check or handling of exceptional conditions, specifically manifesting as failure to check return values from memory allocation functions. When malloc operations fail to allocate required memory, the parsing functions continue execution without proper validation, leading to undefined behavior that ultimately forces the thread handling the message to terminate abruptly. This thread termination creates a cascading effect that can destabilize the entire OPC UA Tunneller service, resulting in complete service unavailability for legitimate users.
From an operational perspective, this vulnerability presents significant risk to industrial control systems and manufacturing environments that rely on OPC UA communications for critical infrastructure management. The denial-of-service condition can be triggered by sending specially crafted messages to the affected system, making it particularly dangerous in environments where continuous operation is essential. The impact extends beyond simple service disruption as it can affect production processes, monitoring systems, and overall operational continuity in industrial settings. The vulnerability aligns with ATT&CK technique T1499.004, which covers network disruption attacks targeting operational technology systems.
The exploitation of this vulnerability requires minimal technical expertise and can be accomplished through simple message crafting techniques that cause malloc failures in the parsing functions. Attackers can leverage this weakness to repeatedly force thread termination, creating sustained denial-of-service conditions that may require manual intervention to resolve. The affected versions prior to 6.3.0.8233 represent a significant security gap that organizations using OPC UA Tunneller components must address immediately. Organizations should implement comprehensive monitoring of OPC UA services to detect unusual thread termination patterns that may indicate exploitation attempts.
Mitigation strategies should focus on immediate software updates to version 6.3.0.8233 or later, which contain the necessary patches to properly validate malloc return values and implement robust error handling. Additionally, network segmentation and access controls should be implemented to limit exposure of OPC UA services to untrusted networks. Security teams should also deploy intrusion detection systems capable of identifying suspicious message patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper error handling in security-sensitive components, particularly in industrial control systems where reliability and availability are paramount. Organizations should conduct thorough vulnerability assessments to identify other components that may exhibit similar memory allocation handling flaws and implement comprehensive testing procedures to validate proper error handling mechanisms.