CVE-2019-6165 in PaperDisplay Hotkey Service
Summary
by MITRE
A DLL search path vulnerability was reported in PaperDisplay Hotkey Service version 1.2.0.8 that could allow privilege escalation. Lenovo has ended support for PaperDisplay Hotkey software as the Night light feature introduced in Windows 10 Build 1703 provides similar features.
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Analysis
by VulDB Data Team • 11/26/2023
The vulnerability identified as CVE-2019-6165 represents a critical DLL search path vulnerability within the PaperDisplay Hotkey Service version 1.2.0.8 developed by Lenovo. This type of vulnerability falls under the broader category of dynamic link library injection flaws that have been systematically catalogued under CWE-426, which specifically addresses the execution of untrusted code through insecure library loading mechanisms. The flaw exists in how the service resolves and loads dynamic link libraries during its operation, creating an opportunity for malicious actors to manipulate the system's library loading process.
The technical implementation of this vulnerability stems from the service's failure to properly validate or restrict the paths from which DLL files are loaded. When the PaperDisplay Hotkey Service executes, it follows a predictable search order that includes the current working directory and other potentially writable locations. Attackers can exploit this by placing a malicious DLL with the same name as a legitimate library in a directory that gets searched before the system's secure library locations. This allows the malicious code to be executed with the elevated privileges of the running service, which typically operates with system-level permissions due to its role in handling hardware-specific hotkey functionality.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and persistent access. Since the service runs with elevated privileges, successful exploitation could enable attackers to install backdoors, modify system files, or establish persistence mechanisms that survive system reboots. The vulnerability is particularly concerning because it targets a legitimate system service that users might not suspect of containing security flaws, making detection and mitigation more challenging. According to ATT&CK framework reference T1059.001, this vulnerability enables malicious code execution through legitimate system processes, while T1068 addresses the privilege escalation techniques that can be achieved through such flaws.
The remediation approach for CVE-2019-6165 requires immediate action to address the root cause of the insecure DLL loading behavior. Organizations should implement immediate patching strategies by updating to the latest version of Lenovo's PaperDisplay Hotkey software or applying the vendor-provided security patches. System administrators should also consider implementing application control policies such as AppLocker or Software Restriction Policies to prevent execution of unauthorized DLL files in critical system directories. Additionally, the security community should recognize that this vulnerability demonstrates the importance of secure coding practices, particularly around library loading mechanisms, as outlined in the OWASP Top 10 security controls. The fact that Lenovo has discontinued support for PaperDisplay Hotkey software underscores the need for organizations to maintain comprehensive software inventory management and to be prepared for end-of-life scenarios where vendor support ceases. The vulnerability also highlights the importance of regular security assessments of legacy software components, particularly those that continue to operate with elevated privileges in modern operating system environments.