CVE-2016-5645 in MicroLogix
Summary
by MITRE
Rockwell Automation MicroLogix 1400 PLC 1766-L32BWA, 1766-L32AWA, 1766-L32BXB, 1766-L32BWAA, 1766-L32AWAA, and 1766-L32BXBA devices have a hardcoded SNMP community, which makes it easier for remote attackers to load arbitrary firmware updates by leveraging knowledge of this community.
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Analysis
by VulDB Data Team • 06/03/2026
The vulnerability identified as CVE-2016-5645 affects Rockwell Automation MicroLogix 1400 series programmable logic controllers including models 1766-L32BWA, 1766-L32AWA, 1766-L32BXB, 1766-L32BWAA, 1766-L32AWAA, and 1766-L32BXBA. These industrial control devices are widely deployed in manufacturing and industrial automation environments where they control critical machinery and processes. The flaw resides in the Simple Network Management Protocol implementation within these PLCs, specifically containing a hardcoded SNMP community string that remains unchanged across all affected devices. This hardcoded credential represents a fundamental security weakness that directly violates principles of secure system design and operational security practices.
The technical implementation of this vulnerability stems from the inclusion of a default, static SNMP community string within the firmware of these industrial devices. When an attacker gains network access to the device, they can leverage this known community string to establish communication with the SNMP agent and execute privileged operations. The specific nature of this flaw allows for remote code execution capabilities through firmware update mechanisms, enabling adversaries to load arbitrary firmware onto the affected PLCs. This represents a critical weakness in the device's security architecture as it eliminates the need for additional reconnaissance or credential discovery phases that would normally be required to compromise such systems. The vulnerability aligns with CWE-798, which specifically addresses the use of hard-coded credentials, and demonstrates how default configurations can create persistent security risks in industrial control systems.
The operational impact of this vulnerability extends far beyond simple network access, as it enables attackers to compromise the integrity and availability of industrial control systems. An attacker who successfully exploits this vulnerability can potentially disrupt manufacturing processes, cause equipment damage, or gain persistent access to critical infrastructure. The ability to load arbitrary firmware updates creates a pathway for attackers to install malicious code, modify operational parameters, or even render the industrial control system inoperable. This threat is particularly concerning in industrial environments where PLCs control safety-critical processes, as the exploitation could lead to physical damage, environmental hazards, or production downtime with potentially severe financial and operational consequences.
Mitigation strategies for this vulnerability require immediate attention from industrial security teams and should include several layers of defensive measures. Organizations must first identify all affected devices within their industrial control networks and implement network segmentation to limit access to these critical assets. The most effective immediate fix involves changing the default SNMP community strings through firmware updates provided by Rockwell Automation, although this requires careful planning to avoid disrupting existing monitoring systems that may rely on these default configurations. Network access control lists should be implemented to restrict SNMP traffic to authorized management stations only, and comprehensive monitoring should be deployed to detect unauthorized SNMP access attempts. According to ATT&CK framework, this vulnerability maps to T1072 for software deployment and T1566 for credential access, highlighting the need for both network-level defenses and operational security measures to prevent exploitation. Long-term security improvements should include regular firmware updates, proper network architecture design with minimal necessary access, and implementation of industrial-specific security protocols that address the unique challenges of operational technology environments.