CVE-2017-11158 in Cloud Station Drive
Summary
by MITRE
Multiple untrusted search path vulnerabilities in installer in Synology Cloud Station Drive before 4.2.5-4396 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 • 12/27/2022
The vulnerability identified as CVE-2017-11158 represents a critical untrusted search path issue affecting Synology Cloud Station Drive versions prior to 4.2.5-4396 on Windows systems. This flaw exists within the installer component of the software and creates a dangerous condition where local attackers can manipulate the system's dynamic link library loading process. The vulnerability stems from the installer's improper handling of the Windows search path, which allows malicious code to be executed with elevated privileges when the system attempts to load required libraries.
The technical exploitation of this vulnerability relies on DLL hijacking techniques where attackers place malicious DLL files with specific names in the current working directory of the vulnerable application. The four identified vulnerable DLL files include shfolder.dll, ntmarta.dll, secur32.dll, and dwmapi.dll, each representing different system components that are typically loaded during normal operation. These files are commonly used by Windows system processes and are often located in system directories, making their hijacking particularly dangerous. The vulnerability is classified under CWE-427, which specifically addresses Uncontrolled Search Path Elements, a well-known weakness that allows attackers to inject malicious code into legitimate applications.
The operational impact of this vulnerability is severe as it enables local attackers to execute arbitrary code with the privileges of the target user, potentially leading to full system compromise. When an attacker successfully places a malicious DLL file in the working directory, the installer will load this malicious code instead of the legitimate system library, effectively creating a backdoor for persistent access. This type of attack is particularly insidious because it leverages legitimate system components and can bypass many standard security controls that monitor for suspicious executable files. The ATT&CK framework categorizes this as a technique involving 'DLL Hijacking' under the T1059.001 sub-technique for 'Command and Scripting Interpreter', where attackers can establish persistence through modified system libraries.
Mitigation strategies for this vulnerability require immediate patching of the Synology Cloud Station Drive software to version 4.2.5-4396 or later, which addresses the untrusted search path issue by implementing proper library loading mechanisms. System administrators should also implement additional security measures including regular monitoring of system directories for unauthorized DLL files, implementing application whitelisting policies, and conducting thorough security audits of installed software components. The vulnerability demonstrates the critical importance of proper privilege management and secure coding practices, particularly when dealing with installer components that may run with elevated privileges. Organizations should also consider implementing the principle of least privilege and regularly review system configurations to minimize the attack surface for similar vulnerabilities.