CVE-2017-11157 in Cloud Station
Summary
by MITRE
Multiple untrusted search path vulnerabilities in installer in Synology Cloud Station Backup 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-2017-11157 represents a critical untrusted search path issue within the Synology Cloud Station Backup installer for Windows systems. This flaw affects versions prior to 4.2.5-4396 and creates a significant security risk by allowing local attackers to execute arbitrary code through DLL hijacking techniques. The vulnerability specifically targets the installer's handling of dynamic link library files in the current working directory, making it particularly dangerous in environments where users may inadvertently execute malicious code. The affected system components include the shfolder.dll, ntmarta.dll, secur32.dll, and dwmapi.dll files, each of which can be exploited to gain unauthorized system access.
From a technical perspective, this vulnerability stems from improper handling of dynamic link library loading mechanisms within the installer process. The installer fails to properly validate or restrict the search path for loading required libraries, allowing attackers to place malicious versions of these DLL files in the current working directory. This behavior aligns with common software security weaknesses classified under CWE-427, which addresses uncontrolled search path dependencies. The attack vector specifically enables DLL hijacking as described in the ATT&CK framework under technique T1059.001 for execution through system components. When the installer runs, it loads these libraries from the current directory rather than from the expected system locations, providing attackers with a direct path to code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can be exploited to establish persistent access within compromised systems. Attackers can leverage this weakness to execute malicious payloads that may include keyloggers, backdoors, or additional exploitation tools. The local nature of the attack means that any user with access to the system where the vulnerable installer is executed can potentially exploit this flaw, making it particularly concerning for enterprise environments where multiple users may have varying privilege levels. The vulnerability's persistence across different Windows versions and its ability to bypass standard security controls makes it a significant concern for system administrators and security teams responsible for protecting corporate infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected systems to version 4.2.5-4396 or later, which addresses the untrusted search path issue through proper DLL loading mechanisms. Organizations should implement strict access controls and user permission management to limit the ability of unauthorized users to execute installers or modify system directories. Security monitoring should focus on detecting unusual DLL loading patterns and unauthorized file modifications in system directories. Additionally, system administrators should conduct regular vulnerability assessments to identify other potential untrusted search path vulnerabilities within their software ecosystem. The remediation process should include implementing application whitelisting policies and ensuring that only trusted software can execute within the environment, following best practices outlined in the CWE guidelines for secure coding and system design.