CVE-2019-5138 in AWK-3131A
Summary
by MITRE
An exploitable command injection vulnerability exists in encrypted diagnostic script functionality of the Moxa AWK-3131A firmware version 1.13. A specially crafted diagnostic script file can cause arbitrary busybox commands to be executed, resulting in remote control over the device. An attacker can send diagnostic while authenticated as a low privilege user to trigger this vulnerability.
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Analysis
by VulDB Data Team • 04/02/2024
The CVE-2019-5138 vulnerability represents a critical command injection flaw within the Moxa AWK-3131A industrial network device firmware version 1.13. This vulnerability specifically targets the encrypted diagnostic script functionality, which serves as a legitimate administrative feature for device troubleshooting and maintenance. The flaw arises from insufficient input validation and sanitization within the diagnostic script processing pipeline, creating an avenue for malicious code execution that bypasses normal security controls.
The technical implementation of this vulnerability stems from improper handling of user-supplied diagnostic script data within the device's firmware. When an authenticated user submits a specially crafted diagnostic script file, the system fails to properly validate or sanitize the input before executing commands through the busybox shell interface. This allows attackers to inject arbitrary commands that are then executed with the privileges of the diagnostic service, effectively enabling remote code execution. The vulnerability operates at the application layer and leverages the device's legitimate diagnostic capabilities as a vector for exploitation, making detection more challenging as the malicious activity appears to originate from normal administrative functions.
The operational impact of this vulnerability is severe for industrial environments relying on Moxa AWK-3131A devices, as it enables attackers with low privilege credentials to achieve full device compromise and potentially establish persistent access. The remote execution capability means attackers can manipulate device configurations, access sensitive network data, or use the compromised device as a pivot point for further attacks within the industrial network infrastructure. This vulnerability particularly affects environments where these devices are deployed in critical infrastructure settings, as the compromise can lead to operational disruptions, data breaches, or even physical security risks depending on the industrial control systems connected to these devices.
Security mitigations for CVE-2019-5138 should prioritize immediate firmware updates from Moxa to address the command injection flaw in the diagnostic script processing functionality. Organizations should implement network segmentation and access controls to limit the impact of potential compromise, ensuring that only authorized personnel can access diagnostic functions. Additionally, monitoring for unusual diagnostic script submissions and implementing strict input validation measures can help detect and prevent exploitation attempts. This vulnerability aligns with CWE-77 and CWE-94 categories related to command injection and code execution flaws, and maps to attack techniques in the MITRE ATT&CK framework under T1059 for command and scripting interpreter and T1078 for valid accounts. Organizations should also consider implementing network intrusion detection systems to monitor for suspicious diagnostic script activities and establish robust patch management processes to prevent similar vulnerabilities in other industrial network devices.