CVE-2011-3489 in RSLogix
Summary
by MITRE
RnaUtility.dll in RsvcHost.exe 2.30.0.23 in Rockwell RSLogix 19 and earlier allows remote attackers to cause a denial of service (crash) via a crafted rna packet with a long string to TCP port 4446 that triggers (1) "a memset zero overflow" or (2) an out-of-bounds read, related to improper handling of a 32-bit size field.
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Analysis
by VulDB Data Team • 04/03/2025
The vulnerability identified as CVE-2011-3489 affects RnaUtility.dll within the RsvcHost.exe process of Rockwell RSLogix 19 and earlier versions, representing a critical security flaw that enables remote attackers to execute denial of service attacks against industrial control systems. This vulnerability specifically targets TCP port 4446 which is used for Rockwell's Remote Network Access protocol, a communication mechanism designed for remote access to programmable logic controllers and other industrial automation devices. The flaw resides in how the software processes incoming network packets, particularly those containing crafted rna data structures that manipulate the 32-bit size field within the protocol implementation.
The technical exploitation of this vulnerability occurs through the manipulation of network packets sent to the designated TCP port 4446, where attackers can craft malicious rna packets containing excessively long string data. This crafted data triggers two distinct but related memory corruption conditions within the RnaUtility.dll module. The first condition, termed "memset zero overflow," represents a classic buffer overflow scenario where the application attempts to write data beyond allocated memory boundaries, potentially causing system instability or complete application crash. The second condition involves an out-of-bounds read operation, where the software attempts to access memory locations beyond the allocated buffer boundaries, leading to unpredictable behavior and system termination. Both conditions stem from improper validation and handling of the 32-bit size field that specifies the length of data within the rna packet structure.
The operational impact of this vulnerability extends beyond simple system crashes, as it directly affects industrial control systems that rely on Rockwell RSLogix for programming and configuration of automation equipment. When exploited, the vulnerability can cause complete service disruption to critical manufacturing and industrial processes, potentially leading to production downtime, safety system failures, and significant financial losses. The remote nature of the attack means that adversaries can exploit this flaw from external networks without requiring physical access to the industrial infrastructure, making it particularly dangerous in environments where security boundaries may be weak or nonexistent. This vulnerability particularly impacts the integrity of industrial communication protocols and can compromise the availability of control systems that are fundamental to operational technology environments.
Mitigation strategies for this vulnerability should focus on immediate network segmentation and access control measures to prevent unauthorized access to TCP port 4446. Organizations should implement network firewalls and access control lists to restrict communication to this port from trusted sources only, while also deploying network monitoring solutions to detect anomalous traffic patterns that may indicate exploitation attempts. The most effective long-term solution involves upgrading to newer versions of Rockwell RSLogix software where this vulnerability has been addressed through proper input validation and memory management practices. Security professionals should also consider implementing intrusion detection systems that can identify and alert on suspicious rna packet structures, and conduct regular vulnerability assessments of industrial control systems to identify similar flaws in other proprietary protocols and applications. This vulnerability demonstrates the importance of proper memory management and input validation in industrial control systems, aligning with CWE-121 for buffer overflow conditions and representing a significant concern for industrial cybersecurity practitioners following ATT&CK techniques related to privilege escalation and denial of service within operational technology environments.