CVE-2018-0593 in OneDrive
Summary
by MITRE
Untrusted search path vulnerability in the installer of Microsoft OneDrive allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 02/22/2020
The vulnerability identified as CVE-2018-0593 represents a critical untrusted search path issue within Microsoft OneDrive's installer component that fundamentally compromises system security through improper dynamic link library loading practices. This flaw resides in the installer's handling of library resolution paths, where the software fails to properly validate or restrict the directories from which it loads dynamic link libraries during the installation process. The vulnerability specifically affects the Windows operating system environment where the installer executes with elevated privileges, creating a pathway for malicious actors to execute arbitrary code with system-level access.
The technical implementation of this vulnerability stems from the installer's reliance on a predictable search order that includes user-writable directories without proper validation mechanisms. When OneDrive's installer runs, it follows a standard library search path that includes the current working directory, system directories, and potentially user-accessible locations where an attacker could place a malicious DLL file. This behavior directly violates the principle of least privilege and exposes the system to privilege escalation attacks through Trojan horse techniques. The vulnerability manifests when the installer encounters a malicious DLL file that matches the expected library name, causing the system to load and execute the attacker-controlled code instead of the legitimate library.
From an operational impact perspective, this vulnerability enables attackers to achieve privilege escalation from standard user level to system administrator level without requiring any additional exploitation techniques. The attack vector is particularly dangerous because it leverages the legitimate installer process, making detection more difficult and allowing the malicious code to execute with the same privileges as the installer itself. The vulnerability affects multiple Windows versions including Windows 7, Windows 8, Windows 8.1, Windows Server 2008, Windows Server 2012, and Windows Server 2016, creating widespread exposure across enterprise environments. Security researchers have classified this issue under CWE-427, which specifically addresses uncontrolled search path vulnerabilities that allow attackers to load malicious code from unintended locations.
The attack scenario typically involves an attacker placing a malicious DLL file in a directory that appears earlier in the search path than the legitimate library location, often within the user's temporary directory or a shared folder that the installer might access. This approach exploits the installer's lack of proper path validation and trust verification mechanisms. The vulnerability aligns with ATT&CK technique T1059.001, which covers execution through command and scripting interpreters, and T1068, which addresses privilege escalation through local exploitation. Organizations using Microsoft OneDrive are particularly vulnerable since the installer runs with elevated privileges and the search path issue exists in the installation process itself rather than requiring additional attack vectors.
Mitigation strategies for this vulnerability include immediate application of Microsoft's security patches and updates that address the untrusted search path behavior by implementing proper library loading validation. System administrators should implement application whitelisting policies to restrict which executables can run during installation processes and ensure that the installer's search path is properly configured to prioritize system directories over user-accessible locations. Additional protective measures include disabling unnecessary user write permissions in directories where the installer might search for libraries and implementing monitoring solutions that detect suspicious DLL loading behaviors. The vulnerability highlights the importance of secure coding practices and proper validation of library loading mechanisms, particularly in components that execute with elevated privileges. Organizations should also consider implementing least privilege principles for installation processes and regularly audit their system's library search paths to prevent similar issues from occurring in other software components.