CVE-2013-5667 in N8800 Nas Server
Summary
by MITRE
The Thecus NAS server N8800 with firmware 5.03.01 allows remote attackers to execute arbitrary commands via a get_userid action with shell metacharacters in the username parameter.
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Analysis
by VulDB Data Team • 08/16/2024
The vulnerability identified as CVE-2013-5667 affects Thecus NAS server N8800 devices running firmware version 5.03.01, representing a critical command injection flaw that enables remote attackers to execute arbitrary system commands without authentication. This vulnerability resides within the web interface's handling of user authentication requests, specifically in the get_userid action functionality that processes username parameters. The flaw demonstrates characteristics consistent with CWE-77, which describes improper neutralization of special elements used in command execution, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The vulnerability exists due to insufficient input validation and sanitization of user-provided data within the authentication processing pipeline, where shell metacharacters are directly incorporated into system commands without proper escaping or filtering mechanisms.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious username parameter containing shell metacharacters such as semicolons, ampersands, or backticks that get interpreted by the underlying shell during the get_userid action execution. This allows attackers to inject and execute arbitrary commands on the target system with the privileges of the web server process, typically running as root or a privileged user. The vulnerability is particularly dangerous because it operates at the application layer and requires no prior authentication, making it a prime target for automated exploitation tools. The command injection occurs within the context of the NAS server's web application, where user input flows directly into system command execution contexts without proper sanitization, creating a direct pathway for remote code execution.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and potential lateral movement within network environments. Attackers can leverage this vulnerability to establish persistent access, exfiltrate sensitive data stored on the NAS server, modify system configurations, or use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability affects organizations relying on Thecus N8800 devices for network-attached storage, potentially exposing critical business data, user credentials, and system configurations. Given that many NAS devices are deployed in environments with limited security monitoring, the impact can be severe as attackers may remain undetected for extended periods while maintaining persistent access to network resources.
Mitigation strategies for CVE-2013-5667 should prioritize immediate firmware updates from Thecus to address the root cause of the vulnerability, as the vendor has likely released patches containing proper input validation and sanitization measures. Network segmentation and access controls should be implemented to limit exposure of NAS devices to untrusted networks, while firewall rules should restrict access to the affected web interface ports. Additional protective measures include disabling unnecessary services, implementing strong authentication mechanisms, and establishing monitoring for unusual command execution patterns. Organizations should also consider deploying web application firewalls to detect and block malicious payload delivery attempts, and conduct regular security assessments of network storage devices to identify similar vulnerabilities. The remediation process should include comprehensive testing of patched firmware to ensure that the fix does not introduce regressions in functionality while maintaining the device's operational integrity.