CVE-2020-13885 in Workspace App
Summary
by MITRE
Citrix Workspace App before 2006.1 on Windows has Insecure Permissions for "%PROGRAMDATA%\Citrix\Citrix Workspace ####\" which allows local users to gain privileges by copying a malicious webio.dll there.
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Analysis
by VulDB Data Team • 10/22/2020
The vulnerability CVE-2020-13885 represents a critical privilege escalation flaw in Citrix Workspace App versions prior to 2006.1 on Windows systems. This issue stems from insecure directory permissions that affect the "%PROGRAMDATA%\Citrix\Citrix Workspace ####\" path, creating a significant security gap that malicious actors can exploit to elevate their privileges. The vulnerability specifically targets the program data directory where Citrix Workspace App stores its components, making it a prime target for local privilege escalation attacks.
The technical flaw manifests through improper access controls on the Citrix Workspace App installation directory structure. When the application runs with elevated privileges during installation or operation, it creates a directory structure that allows local users to write files to critical locations. The vulnerability specifically enables attackers to copy a malicious webio.dll file into the targeted directory, which then gets executed with elevated privileges. This occurs because the directory permissions are set too broadly, allowing write access to users who should only have read access. The flaw aligns with CWE-276, which addresses incorrect permissions for critical resources, and represents a classic case of insufficient access control.
The operational impact of this vulnerability is severe as it allows any local user to potentially gain system-level privileges without requiring administrative credentials. Attackers can leverage this flaw by simply copying a malicious webio.dll file into the designated directory, effectively bypassing standard security controls. Once executed, the malicious DLL can perform actions that would normally require administrative privileges, potentially leading to complete system compromise. This vulnerability undermines the principle of least privilege and creates an attack surface that can be exploited by both malicious insiders and external threat actors who have gained initial access to a system. The attack vector is particularly concerning because it requires minimal privileges to exploit and can result in persistent access to the compromised system.
Mitigation strategies for CVE-2020-13885 should focus on immediate patching of affected Citrix Workspace App installations to version 2006.1 or later. Organizations should also implement proper directory permissions for the Citrix Workspace App installation directories, ensuring that only authorized users and processes can write to critical locations. System administrators should conduct thorough security audits to identify and correct similar permission issues across all installed applications. The remediation process should include verifying that the program data directories have appropriate access controls, typically restricting write access to administrators only. Additionally, implementing application whitelisting solutions and monitoring for unauthorized file modifications in these directories can provide additional layers of defense. This vulnerability demonstrates the importance of maintaining proper access controls and regularly updating software to address known security flaws, as outlined in the mitre ATT&CK framework's privilege escalation techniques. Organizations should also consider implementing endpoint detection and response solutions to monitor for suspicious file copy operations in sensitive directories, as this represents a common exploitation pattern for local privilege escalation attacks.