CVE-2017-7876 in QTS
Summary
by MITRE
QNAP QTS before 4.2.6 build 20170517 allows command injection.
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Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2017-7876 affects QNAP QTS (QNAP Turbo Server) operating systems prior to version 4.2.6 build 20170517, representing a critical command injection flaw that enables remote attackers to execute arbitrary commands on affected systems. This vulnerability resides within the web interface of the QNAP QTS platform, specifically in how the system processes user input through certain API endpoints and web forms. The flaw stems from inadequate input validation and sanitization mechanisms that fail to properly escape or filter user-supplied data before incorporating it into system commands or shell executions.
The technical implementation of this vulnerability allows attackers to inject malicious commands through crafted input parameters that are subsequently processed by the underlying operating system. When legitimate users submit data through web forms or API calls, the system does not adequately sanitize these inputs, creating an environment where attackers can append shell commands that get executed with the privileges of the web server process. This type of vulnerability maps directly to CWE-77 which defines command injection as the injection of a command into a shell by manipulating input data. The attack vector typically involves sending specially crafted HTTP requests that contain malicious payloads designed to exploit the lack of proper input validation.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete control over affected QNAP devices. Once exploited, attackers can execute arbitrary commands with the privileges of the web server process, which typically runs with elevated permissions on the system. This access enables a wide range of malicious activities including but not limited to data exfiltration, system reconnaissance, privilege escalation to root access, installation of backdoors, and deployment of cryptocurrency mining software. The vulnerability affects QNAP devices running QTS versions before 4.2.6 build 20170517, making it particularly dangerous as many organizations may have legacy systems that have not been updated. The attack surface is broad since QNAP devices are commonly deployed in enterprise environments for network-attached storage and media streaming services, making them attractive targets for cybercriminals seeking persistent access to network infrastructure.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.001 which describes command and scripting interpreter execution, and T1068 which covers exploit for privilege escalation. The vulnerability can be leveraged by attackers to establish persistent access through various attack chains, potentially leading to lateral movement within networks where QNAP devices are deployed. Organizations should implement immediate mitigations including mandatory firmware updates to QTS 4.2.6 build 20170517 or later versions, network segmentation to limit access to QNAP devices, and implementation of web application firewalls to detect and block suspicious command injection attempts. Additionally, regular security assessments should be conducted to identify any remaining vulnerable systems and ensure proper input validation is implemented across all web applications and interfaces. The vulnerability demonstrates the critical importance of maintaining up-to-date firmware and implementing robust input validation practices as recommended in industry standards such as NIST SP 800-160 and ISO 27001.