CVE-2021-41334 in Windows
Summary
by MITRE • 10/13/2021
Windows Desktop Bridge Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/15/2021
This vulnerability exists within the Windows Desktop Bridge component that facilitates the execution of desktop applications within the Windows Store environment. The flaw represents a critical elevation of privilege issue that allows attackers to escalate their privileges from standard user level to system level access. The vulnerability specifically affects the way the Desktop Bridge handles application execution contexts and privilege management, creating a pathway for malicious code to bypass security restrictions that normally protect system resources. The issue stems from improper validation of execution contexts when desktop applications are launched through the Windows Store framework, enabling unauthorized privilege escalation.
The technical root cause of CVE-2021-41334 lies in the Desktop Bridge's insufficient privilege checking mechanisms during application runtime. When applications are executed through this bridge, the system fails to properly verify the security context and execution permissions, allowing malicious actors to manipulate the execution environment. This weakness is categorized under CWE-276 which addresses improper privilege management and inadequate access control mechanisms. The vulnerability manifests when the Desktop Bridge component does not adequately enforce security boundaries between different privilege levels, creating an attack surface where standard user processes can potentially execute with elevated privileges. The flaw specifically impacts the Windows AppContainer security model that is designed to isolate applications from system resources and other applications.
The operational impact of this vulnerability is severe as it enables attackers to gain system-level privileges without requiring administrative access or user interaction. An attacker could exploit this vulnerability by crafting malicious desktop applications or by manipulating existing applications to execute with elevated privileges. Once successfully exploited, the attacker gains complete control over the affected system, allowing for persistent access, data exfiltration, and further network reconnaissance. The vulnerability affects Windows 10 versions and Windows 11 systems that have the Desktop Bridge functionality enabled, making it particularly concerning for enterprise environments where standard user accounts are commonly used. This weakness can be leveraged in combination with other attack vectors to create persistent backdoors or to escalate privileges for more extensive system compromise.
Mitigation strategies for CVE-2021-41334 should include immediate installation of Microsoft security updates that address the privilege escalation flaw in the Desktop Bridge component. Organizations should also implement strict application control policies that limit the execution of desktop applications through the Windows Store framework. Network segmentation and monitoring should be enhanced to detect unusual privilege escalation attempts or unauthorized application executions. Security teams should disable unnecessary Desktop Bridge functionality where possible and regularly audit application execution contexts to identify potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation, and organizations should monitor for indicators of compromise related to unexpected privilege elevation. Additionally, implementing least privilege principles and regularly reviewing user permissions can help limit the potential impact of successful exploitation attempts.