CVE-2017-17027 in QTS
Summary
by MITRE
A buffer overflow vulnerability in FTP service in QNAP QTS version 4.2.6 build 20171026, 4.3.3.0378 build 20171117, 4.3.4.0387 (Beta 2) build 20171116 and earlier could allow remote attackers to execute arbitrary code on NAS devices.
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Analysis
by VulDB Data Team • 12/15/2019
The vulnerability identified as CVE-2017-17027 represents a critical buffer overflow flaw within the File Transfer Protocol service of QNAP QTS operating systems. This issue affects multiple versions including 4.2.6, 4.3.3, and 4.3.4 builds released in late 2017, creating a significant security risk for network-attached storage devices. The flaw exists in the FTP service implementation where insufficient input validation allows attackers to craft malicious payloads that can overflow buffer structures and potentially overwrite critical memory segments. This vulnerability falls under the CWE-121 buffer overflow category, specifically categorized as a stack-based buffer overflow that can lead to arbitrary code execution. The attack vector requires remote network access to the affected FTP service, making it particularly dangerous as attackers can exploit this weakness from external networks without requiring physical access to the device.
The technical implementation of this vulnerability stems from improper handling of user-supplied data within the FTP service's command processing routines. When the FTP service receives certain malformed commands or arguments, it fails to properly validate input length before copying data into fixed-size buffers. This allows attackers to exceed buffer boundaries and overwrite adjacent memory locations including return addresses, function pointers, or other critical control data. The exploitation process typically involves crafting specific FTP commands with overly long arguments that trigger the buffer overflow condition, potentially enabling attackers to inject and execute malicious code within the context of the FTP service process. The vulnerability is particularly concerning because it affects the core operating system service that handles network file transfers, providing attackers with a direct pathway to compromise the entire NAS device.
The operational impact of CVE-2017-17027 extends far beyond simple service disruption, as successful exploitation can result in complete system compromise. Attackers who successfully exploit this vulnerability can gain unauthorized access to all data stored on the affected NAS device, potentially including sensitive corporate information, personal files, or confidential business data. The compromised device can then serve as a foothold for further network infiltration, allowing attackers to use the NAS as a pivot point to attack other systems within the local network. Additionally, the vulnerability could enable attackers to install persistent backdoors, modify system configurations, or even use the compromised device for conducting further attacks against external targets. This makes the vulnerability particularly dangerous in enterprise environments where NAS devices often serve as central repositories for critical data and may be accessible from multiple network segments.
Organizations should implement immediate mitigations including applying the latest firmware updates from QNAP that address this specific vulnerability, as well as implementing network segmentation to limit access to FTP services. The recommended approach involves disabling unnecessary FTP services where possible and implementing strong access controls including authentication mechanisms and IP filtering. Network monitoring should be enhanced to detect unusual FTP traffic patterns that might indicate exploitation attempts. Security professionals should also consider implementing intrusion detection systems that can identify and alert on known attack signatures targeting this specific buffer overflow vulnerability. According to ATT&CK framework, this vulnerability maps to multiple techniques including T1072 Application Deployment Software and T1059 Command and Scripting Interpreter, as attackers can leverage the compromised system to execute commands and deploy additional malicious software. Organizations should also conduct thorough vulnerability assessments to identify any other potentially affected QNAP devices within their network infrastructure and ensure proper patch management processes are in place to prevent similar issues in the future.