CVE-2018-14893 in NSA325 V2
Summary
by MITRE
A system command injection vulnerability in zyshclient in ZyXEL NSA325 V2 version 4.81 allows attackers to execute system commands via the web application API.
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Analysis
by VulDB Data Team • 04/15/2020
The vulnerability identified as CVE-2018-14893 represents a critical system command injection flaw within the zyshclient component of ZyXEL NSA325 V2 network security appliances running firmware version 4.81. This issue exposes the device to unauthorized command execution through the web application programming interface, creating a significant security risk for organizations relying on these network appliances for protection. The vulnerability stems from inadequate input validation and sanitization mechanisms within the web API that processes user-supplied data, allowing malicious actors to inject arbitrary system commands directly into the underlying operating system.
The technical implementation of this vulnerability involves the zyshclient component failing to properly sanitize or validate input parameters received through the web application API endpoints. When legitimate users or attackers submit crafted payloads containing system commands through the API interface, the system processes these inputs without adequate filtering or escaping mechanisms. This lack of input validation creates a direct pathway for command injection attacks, where malicious commands can be executed with the privileges of the web application process, typically running with elevated system permissions. The vulnerability manifests specifically in how the system handles command execution requests through the API, bypassing normal security controls and authentication mechanisms that should protect the underlying system from unauthorized command execution.
The operational impact of this vulnerability extends beyond simple command execution, creating potential for complete system compromise and unauthorized access to network resources. Attackers can leverage this vulnerability to gain persistent access to the appliance, potentially leading to data exfiltration, network reconnaissance, or use of the compromised device as a pivot point for attacking other systems within the network. The implications are particularly severe for network security appliances like the NSA325 V2, which are designed to protect network infrastructure and are often placed in critical positions within enterprise networks. The vulnerability effectively undermines the security posture of organizations relying on these devices, as they may be unknowingly providing attackers with elevated privileges to execute arbitrary code on their network perimeter devices. This creates opportunities for attackers to establish backdoors, modify firewall rules, or access sensitive network information that should remain protected.
Mitigation strategies for CVE-2018-14893 should prioritize immediate firmware updates from ZyXEL to address the command injection vulnerability, as this represents the most effective solution to prevent exploitation. Organizations should also implement network segmentation and access controls to limit exposure of affected devices to untrusted networks, while monitoring network traffic for suspicious command execution patterns that might indicate exploitation attempts. Additional defensive measures include implementing web application firewalls to filter malicious API requests and conducting thorough security assessments of all network appliances to identify similar vulnerabilities. The vulnerability aligns with CWE-77 and CWE-94 categories related to command injection and code injection flaws, and corresponds to ATT&CK techniques such as T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation. Regular security patch management processes should be established to ensure timely updates of network security appliances and prevent similar vulnerabilities from being exploited in the future.