CVE-2020-22809 in WindScribe
Summary
by MITRE • 05/10/2021
In Windscribe v1.83 Build 20, 'WindscribeService' has an Unquoted Service Path that facilitates privilege escalation.
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Analysis
by VulDB Data Team • 05/13/2021
The vulnerability identified as CVE-2020-22809 affects Windscribe version 1.83 Build 20 and represents a critical privilege escalation risk through an unquoted service path configuration. This flaw resides within the WindscribeService component that is part of the broader Windscribe VPN client software ecosystem. The service path configuration lacks proper quotation around the executable path, creating a dangerous opportunity for malicious actors to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability stems from improper service path handling where the Windows service manager does not properly quote the executable path when registering the WindscribeService. This occurs because the service installation process fails to wrap the path in quotation marks, allowing Windows to interpret the path as a sequence of directory names and executable components rather than a single quoted path. When the service path contains spaces, Windows will traverse the directory structure from left to right, attempting to execute files at each level until it finds the actual executable.
This vulnerability directly maps to CWE-428, which describes "Unquoted Service Path" and is classified as a privilege escalation vector in the MITRE ATT&CK framework under the technique T1068. The flaw enables attackers to place malicious executables in directories along the path that Windows searches, effectively hijacking the service execution flow. The service operates with SYSTEM privileges, making any successful exploitation result in full system compromise. Attackers can simply place a malicious executable named WindscribeService.exe in a directory that appears earlier in the Windows search path, such as C:\Program Files\, and the service will execute this malicious binary instead of the legitimate one.
The operational impact of this vulnerability is severe as it allows any local user to escalate privileges to SYSTEM level without requiring additional authentication or complex exploitation techniques. The attack surface is broad since the service path typically includes standard Windows installation directories where attackers can place malicious files. Once exploited, the attacker gains complete control over the system, including the ability to access all user data, modify system configurations, and establish persistence mechanisms. The vulnerability is particularly dangerous because it requires no user interaction beyond the initial system compromise and can be exploited silently in the background.
Mitigation strategies for this vulnerability should include immediate patching of the Windscribe software to version 1.84 or later, which addresses the unquoted service path issue. System administrators should also implement proper service path validation and ensure that all service installations properly quote executable paths. The Windows Service Control Manager should be configured to prevent execution of binaries from insecure locations, and the principle of least privilege should be enforced by limiting write access to service directories. Additionally, regular security auditing should include verification of service paths to ensure proper quoting and prevent similar issues in other software components. Network segmentation and monitoring solutions should also be employed to detect unauthorized binary installations in critical system directories.