CVE-2017-3757 in ElanTech Touchpad Driver
Summary
by MITRE
An unquoted service path vulnerability was identified in the driver for the ElanTech Touchpad, various versions, used on some Lenovo brand notebooks (not ThinkPads). This could allow an attacker with local privileges to execute code with administrative privileges.
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Analysis
by VulDB Data Team • 11/11/2019
The vulnerability CVE-2017-3757 represents a critical security flaw in the Elantech touchpad driver software that affects specific Lenovo notebook models. This issue manifests as an unquoted service path vulnerability, which occurs when Windows service paths containing spaces are not properly quoted in the registry. The affected driver is part of the Elantech touchpad functionality that Lenovo incorporates into various notebook models, excluding their ThinkPad line. The vulnerability specifically impacts the service installation process where the path to the executable file lacks proper quotation marks, creating a potential attack vector that can be exploited by local users with minimal privileges.
The technical implementation of this vulnerability stems from improper service path configuration where the Windows service registry entry for the Elantech touchpad driver does not enclose the executable path in quotation marks. When Windows attempts to launch the service, it interprets the path as multiple separate arguments, allowing an attacker to place a malicious executable in a directory that appears before the legitimate service path in the Windows search order. This behavior aligns with CWE-428, which describes the weakness of unquoted service paths in Windows environments. The vulnerability operates under the principle that Windows will execute the first executable it finds in the PATH environment variable, potentially executing a malicious binary instead of the intended legitimate service executable.
The operational impact of this vulnerability is significant as it enables privilege escalation from a local user account to administrative privileges without requiring any special authentication or network access. An attacker with basic local access to the affected system can leverage this vulnerability to execute arbitrary code with system-level privileges, effectively compromising the entire system. This makes the vulnerability particularly dangerous in enterprise environments where local access might be more readily available through social engineering or physical access attacks. The attack requires no network connectivity and can be executed entirely within the local system context, making it difficult to detect through traditional network-based security monitoring tools.
Mitigation strategies for CVE-2017-3757 should focus on immediate patching of the affected Elantech touchpad driver software through official Lenovo updates or Windows driver updates. System administrators should also implement proper service path configuration reviews to ensure all service paths are properly quoted in the Windows registry. The vulnerability can be addressed through the ATT&CK framework technique T1068, which involves privilege escalation through service misconfiguration, by implementing proper access controls and service path validation. Additionally, organizations should conduct regular security assessments to identify other unquoted service paths within their Windows environments, as similar vulnerabilities may exist in other software components. The remediation process should include both immediate patch deployment and long-term configuration hardening to prevent similar issues in the future, ensuring that all service installations follow secure coding practices and proper path quoting conventions.