CVE-2018-20162 in TransPort LR54
Summary
by MITRE
Digi TransPort LR54 4.4.0.26 and possible earlier devices have Improper Input Validation that allows users with 'super' CLI access privileges to bypass a restricted shell and execute arbitrary commands as root.
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Analysis
by VulDB Data Team • 08/03/2023
The vulnerability identified as CVE-2018-20162 affects Digi TransPort LR54 industrial communication devices running firmware versions 4.4.0.26 and earlier. This represents a critical security flaw that undermines the device's privilege separation mechanisms and allows authenticated attackers with super user command line interface access to escalate their privileges and execute arbitrary commands with root-level permissions. The issue stems from inadequate input validation within the device's command processing pipeline, creating a pathway for malicious command injection that bypasses intended security controls.
The technical flaw manifests in the improper validation of user-supplied input within the restricted shell environment of the device. When a user with super CLI privileges attempts to execute commands, the system fails to properly sanitize or validate the input before processing. This vulnerability falls under CWE-20, Improper Input Validation, which is a fundamental weakness that enables attackers to inject malicious commands that are then executed with elevated privileges. The restricted shell mechanism that should limit user capabilities is effectively circumvented through this input validation bypass, allowing attackers to gain unauthorized root access to the system.
The operational impact of this vulnerability is severe for industrial environments where Digi TransPort LR54 devices are deployed for critical communications and network management. An attacker who has already obtained super user credentials can leverage this flaw to execute arbitrary code with full system privileges, potentially leading to complete system compromise, data exfiltration, or disruption of industrial control processes. The vulnerability particularly affects environments where these devices serve as network gateways or communication bridges between critical infrastructure components. This weakness can be exploited to establish persistent backdoors, modify system configurations, or disable security controls, making it a significant threat to operational technology security.
Mitigation strategies for CVE-2018-20162 should focus on immediate firmware updates from Digi to address the input validation flaw. Organizations should implement strict access controls and privilege management, ensuring that only authorized personnel have super user CLI access. Network segmentation and monitoring should be enhanced to detect suspicious command execution patterns. The vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, where adversaries execute commands with elevated privileges. Additionally, implementing input sanitization measures and restricting CLI access to essential personnel only can significantly reduce the attack surface. Organizations should also consider deploying network intrusion detection systems to monitor for anomalous command execution patterns that might indicate exploitation attempts. The remediation approach should include comprehensive security assessments of all industrial devices to identify similar vulnerabilities in the broader operational technology environment.