CVE-2011-4871 in Opcsystems.net
Summary
by MITRE
Open Automation Software OPC Systems.NET before 5.0 allows remote attackers to cause a denial of service via a malformed .NET RPC packet on TCP port 58723.
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Analysis
by VulDB Data Team • 03/19/2025
The vulnerability identified as CVE-2011-4871 affects Open Automation Software OPC Systems.NET versions prior to 5.0, presenting a significant security risk that enables remote attackers to execute denial of service attacks. This flaw specifically targets the communication protocol used by OPC (OLE for Process Control) systems which are widely deployed in industrial automation environments for data exchange between devices and applications. The vulnerability manifests through the processing of malformed .NET Remote Procedure Call (RPC) packets, which are transmitted over TCP port 58723, a port commonly associated with OPC communication services. The affected system fails to properly validate incoming RPC packets, creating an exploitable condition that can be leveraged by malicious actors to disrupt normal operations.
The technical implementation of this vulnerability stems from inadequate input validation within the OPC Systems.NET software stack. When a malformed RPC packet is received on the designated TCP port 58723, the system's parsing mechanism does not adequately sanitize or reject malformed data structures, leading to unexpected behavior that ultimately results in system instability. This type of vulnerability falls under the CWE-129 category of Improper Input Validation, where the software fails to properly validate or sanitize input data before processing. The flaw represents a classic buffer overflow or parsing error condition where malformed data causes the application to crash or become unresponsive, effectively rendering the OPC service unavailable to legitimate users and operators.
The operational impact of CVE-2011-4871 extends beyond simple service disruption, as OPC systems form critical components of industrial control systems and supervisory control and data acquisition networks. When attackers exploit this vulnerability, they can cause cascading failures within industrial environments where OPC communication is essential for process control, monitoring, and data collection. The attack vector is particularly concerning because it requires no authentication or specialized privileges, making it accessible to any remote attacker who can reach the target system on TCP port 58723. This characteristic aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries target network infrastructure to deny services to legitimate users. The vulnerability affects systems across various industrial sectors including manufacturing, energy, water treatment, and other process control environments where OPC communication protocols are prevalent.
Organizations should implement immediate mitigation strategies including network segmentation to isolate OPC systems from general network access, firewall rules to restrict TCP port 58723 access to authorized systems only, and regular security updates to ensure OPC Systems.NET is patched to version 5.0 or later. The vulnerability demonstrates the critical importance of input validation in industrial communication protocols and highlights the need for robust security practices in operational technology environments. Security monitoring should include detection of malformed RPC packets and unusual traffic patterns on the affected port, while system administrators should maintain updated threat intelligence feeds to identify potential exploitation attempts. The remediation process requires careful planning due to the critical nature of OPC systems in industrial environments, ensuring that patches are tested in controlled environments before deployment to production systems to prevent unintended operational disruptions.