CVE-2017-13070 in Qsync
Summary
by MITRE
A DLL Hijacking vulnerability in QNAP Qsync for Windows (exe) version 4.2.2.0724 and earlier could allow remote attackers to execute arbitrary code on Windows machines.
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Analysis
by VulDB Data Team • 01/26/2021
The vulnerability identified as CVE-2017-13070 represents a critical DLL hijacking flaw within QNAP Qsync for Windows software version 4.2.2.0724 and earlier. This vulnerability stems from improper handling of dynamic link library loading mechanisms during the software execution process. The flaw allows remote attackers to place malicious DLL files in strategic locations where the legitimate Qsync application expects to find its dependencies, thereby enabling unauthorized code execution on targeted Windows systems. The vulnerability specifically affects the Windows implementation of QNAP Qsync, which is designed for file synchronization and sharing across networked devices. Attackers can exploit this weakness by placing specially crafted malicious DLL files in directories that are searched before the legitimate QNAP DLLs, taking advantage of the Windows DLL search order mechanism that prioritizes certain paths over others.
The technical implementation of this vulnerability aligns with CWE-426, which describes the insecure loading of dynamic link libraries, and is classified as a privilege escalation vulnerability under the ATT&CK framework. The flaw occurs because the Qsync application does not properly validate or restrict the paths from which DLLs are loaded, creating an opportunity for attackers to inject malicious code into the execution flow. This particular vulnerability is particularly dangerous because it can be exploited remotely without requiring local access to the target system, making it an attractive vector for attackers seeking to compromise Windows machines running vulnerable QNAP Qsync versions. The exploitation process involves placing malicious DLL files in directories that are part of the Windows DLL search path, allowing the system to load these unauthorized libraries when Qsync executes, thereby executing attacker-controlled code with the privileges of the Qsync process.
The operational impact of this vulnerability extends beyond simple code execution, as it can potentially allow attackers to establish persistent access, escalate privileges, and move laterally within compromised networks. Organizations using QNAP Qsync software are at risk of unauthorized access to sensitive data, system compromise, and potential use as a foothold for broader network infiltration. The vulnerability affects all Windows systems running vulnerable versions of QNAP Qsync, making it particularly concerning for enterprise environments where such software might be deployed across multiple machines. The remote exploit capability means that attackers can target systems from outside the network perimeter, potentially bypassing traditional network security controls. This vulnerability demonstrates the critical importance of proper DLL loading practices and the risks associated with insecure library resolution mechanisms in Windows applications, particularly those used in enterprise file sharing and synchronization environments.
Mitigation strategies for CVE-2017-13070 should prioritize immediate software updates to the latest QNAP Qsync versions that address the DLL loading vulnerability. Organizations should implement strict access controls and network segmentation to limit exposure of QNAP Qsync systems to untrusted networks. The implementation of application whitelisting policies can help prevent execution of unauthorized DLL files, while regular security audits should verify proper DLL loading practices in all software applications. System administrators should monitor for suspicious DLL loading activities and implement endpoint protection solutions that can detect and block malicious DLL injection attempts. Additionally, the principle of least privilege should be enforced to limit the potential damage from successful exploitation attempts. Organizations should also consider implementing network-based intrusion detection systems to identify and alert on potential exploitation attempts targeting this specific vulnerability. The vulnerability serves as a reminder of the critical need for secure coding practices and the importance of validating library paths in application development, particularly for software that handles sensitive data synchronization across networked environments.