CVE-2016-4500 in UC-7408 LX-Plus
Summary
by MITRE
Moxa UC-7408 LX-Plus devices allow remote authenticated users to write to the firmware, and consequently render a device unusable, by leveraging root access.
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Analysis
by VulDB Data Team • 12/27/2018
The CVE-2016-4500 vulnerability affects Moxa UC-7408 LX-Plus industrial network devices, representing a critical security flaw in embedded systems designed for industrial automation and control environments. This vulnerability stems from improper privilege escalation mechanisms within the device's firmware update process, allowing authenticated users with limited privileges to escalate their access level and gain root permissions. The flaw exists in the device's authentication and authorization framework, where the system fails to properly validate user privileges during firmware modification operations, creating an exploitable path for malicious actors who have already established initial access to the device.
The technical implementation of this vulnerability involves a privilege escalation flaw that enables attackers to bypass normal access controls during firmware write operations. When authenticated users attempt to perform firmware updates, the system incorrectly validates their permissions, allowing them to execute privileged operations without proper authorization. This represents a classic privilege escalation vulnerability that can be classified under CWE-269 Improper Privilege Management, where the system fails to enforce proper access controls for critical operations. The vulnerability specifically targets the firmware update mechanism, which is a critical component in industrial control systems where device integrity is paramount for operational continuity and safety.
From an operational impact perspective, this vulnerability poses severe risks to industrial environments that rely on Moxa devices for critical infrastructure management. An attacker who has already gained initial access to the device can leverage this flaw to completely compromise the system by writing arbitrary firmware code, effectively rendering the device unusable or potentially allowing for complete system takeover. The implications extend beyond simple device unavailability, as industrial control systems often operate in environments where device failure can lead to production halts, safety hazards, or security breaches that affect entire facilities. This vulnerability directly impacts the integrity and availability aspects of the CIA triad, potentially allowing for both denial of service and potential compromise of operational technology systems.
The exploitation of this vulnerability requires an attacker to first establish authenticated access to the device, which typically involves obtaining valid credentials through various means such as credential theft, default credential usage, or other initial compromise techniques. Once authenticated, the attacker can leverage the privilege escalation flaw to gain root access and subsequently write to the firmware, creating a persistent threat that can survive system reboots and potentially allow for the installation of backdoors or malicious code. This vulnerability aligns with ATT&CK technique T1068 Privilege Escalation, specifically focusing on the exploitation of system vulnerabilities to gain higher-level access rights. Organizations using these devices should consider implementing network segmentation, regular credential rotation, and firmware update monitoring to mitigate the risk of exploitation.
Mitigation strategies for CVE-2016-4500 should focus on immediate firmware updates provided by Moxa to address the privilege escalation flaw, combined with network security controls to limit access to these devices. Network segmentation should be implemented to restrict access to industrial control systems, ensuring that only authorized personnel can reach these critical devices. Regular security assessments should be conducted to identify and remediate similar privilege escalation vulnerabilities in other industrial equipment. Additionally, organizations should implement robust change management processes for firmware updates, ensuring that all modifications to industrial control system components are properly authorized and validated. The vulnerability highlights the importance of secure firmware development practices and proper access control implementation in industrial environments where system integrity and operational continuity are critical factors for business operations and public safety.