CVE-2017-11160 in Assistant
Summary
by MITRE
Multiple untrusted search path vulnerabilities in installer in Synology Assistant before 6.1-15163 on Windows allows local attackers to execute arbitrary code and conduct DLL hijacking attack via a Trojan horse (1) shfolder.dll, (2) ntmarta.dll, (3) secur32.dll or (4) dwmapi.dll file in the current working directory.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2017-11160 represents a critical untrusted search path issue within the Synology Assistant installer component for Windows systems. This flaw affects versions prior to 6.1-15163 and exposes systems to arbitrary code execution through carefully crafted DLL hijacking attacks. The vulnerability specifically targets the installer's handling of dynamic link library files, creating an environment where malicious actors can escalate privileges and gain unauthorized system access. The affected DLL files include shfolder.dll, ntmarta.dll, secur32.dll, and dwmapi.dll, each representing different system components that are commonly targeted in such attacks due to their legitimate presence and usage patterns within Windows environments.
The technical exploitation of this vulnerability occurs when an attacker places malicious versions of the targeted DLL files in the current working directory where the Synology Assistant installer executes. This creates a classic DLL hijacking scenario where the Windows loader searches for required libraries in predictable locations, including the current working directory, before checking system directories. The vulnerability stems from improper library resolution mechanisms within the installer's execution context, allowing attackers to substitute legitimate system DLLs with malicious counterparts that execute with the privileges of the installer process. This behavior aligns with CWE-426 Untrusted Search Path, which specifically addresses the security implications of applications searching for libraries in insecure locations. The flaw operates at the system level, leveraging Windows' default DLL search order to redirect execution flow to attacker-controlled code.
The operational impact of this vulnerability extends beyond simple code execution, creating potential for privilege escalation and persistent system compromise. Local attackers who can place malicious DLL files in the working directory have the capability to execute arbitrary code with the privileges of the installer process, which typically runs with elevated permissions. This vulnerability enables attackers to establish backdoors, escalate privileges to SYSTEM level access, and maintain persistence within the compromised environment. The attack vector is particularly concerning because it requires minimal user interaction beyond the presence of the vulnerable installer, making it suitable for automated exploitation campaigns. The vulnerability also aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter, as attackers can leverage the installer process to execute malicious payloads.
Mitigation strategies for CVE-2017-11160 focus on both immediate remediation and long-term architectural improvements. The primary solution involves updating to Synology Assistant version 6.1-15163 or later, which addresses the untrusted search path issue through proper library resolution mechanisms. Organizations should implement strict file access controls and privilege separation to limit the ability of local attackers to place malicious files in critical directories. The implementation of Windows Defender Application Control or similar application whitelisting solutions can prevent unauthorized DLL execution. Additionally, system administrators should conduct regular security audits to identify and remove vulnerable software installations, while implementing monitoring solutions that detect suspicious DLL loading activities. The vulnerability serves as a reminder of the importance of secure coding practices and proper library resolution techniques, particularly in installer and system utility components that operate with elevated privileges.