CVE-2021-1642 in Windows
Summary
by MITRE • 01/13/2021
Windows AppX Deployment Extensions Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-1685.
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Analysis
by VulDB Data Team • 10/09/2024
This vulnerability exists within the Windows AppX Deployment Extensions component which handles the installation and management of modern Windows applications packaged as AppX containers. The flaw represents a privilege escalation issue that allows attackers to elevate their security context from standard user level to system level privileges. The vulnerability specifically affects the way the system validates and processes AppX package installations, creating an opportunity for malicious actors to exploit improper access controls and execute arbitrary code with elevated permissions. The issue is particularly concerning because it leverages the legitimate Windows application deployment mechanisms to bypass normal security boundaries.
The technical root cause stems from insufficient input validation and access control checks within the AppX deployment service. When processing AppX package installations, the system fails to properly verify the authenticity and integrity of the package metadata, allowing attackers to manipulate deployment parameters that should be restricted to administrative users. This weakness enables a local attacker to craft malicious AppX packages or modify existing ones in a way that triggers the vulnerable code path. The flaw operates at the kernel level where the AppX deployment service executes with elevated privileges, making it a prime target for privilege escalation attacks. According to CWE-269, this represents an inadequate privilege management issue that directly enables unauthorized privilege escalation through improper access control mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a reliable method to gain system-level control without requiring physical access or complex exploitation techniques. Once exploited, the attacker can install malicious applications, modify system files, create persistent backdoors, and access sensitive data across all user accounts. The vulnerability affects multiple Windows versions including Windows 10 and Windows Server 2019, making it particularly dangerous in enterprise environments where these systems are prevalent. The attack surface is broad since AppX deployments are commonly used for both legitimate software installations and automated deployment scenarios in corporate networks. This vulnerability aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and specifically targets the Windows kernel and system services.
Mitigation strategies should focus on immediate patch application as Microsoft released security updates addressing this specific vulnerability in their regular monthly security updates. Organizations should implement the principle of least privilege by limiting user accounts to standard privileges and avoiding administrative rights for routine operations. Network segmentation and application whitelisting can help reduce the attack surface by preventing unauthorized AppX package installations. System monitoring should be enhanced to detect unusual AppX deployment activities, particularly those occurring outside of normal administrative procedures. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing comprehensive vulnerability management programs that address both known and emerging threats in Windows deployment services. Security teams should also consider implementing behavioral analysis tools that can detect anomalous privilege escalation patterns and automated deployment activities that deviate from established baselines.