CVE-2021-1650 in Windows
Summary
by MITRE • 01/13/2021
Windows Runtime C++ Template Library Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/09/2024
The Windows Runtime C++ Template Library vulnerability identified as CVE-2021-1650 represents a critical elevation of privilege flaw within Microsoft's Windows operating systems. This vulnerability specifically affects the Windows Runtime C++ Template Library component which serves as a foundational framework for developing applications that utilize the Windows Runtime API. The flaw resides in how the library handles certain memory operations and object lifecycle management, creating opportunities for malicious actors to escalate their privileges from standard user level to SYSTEM level access. The vulnerability impacts multiple Windows versions including Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, and Windows Server 2022, making it a widespread concern across enterprise and consumer environments.
Technical exploitation of this vulnerability occurs through improper memory management within the C++ Template Library implementation. The flaw manifests when applications utilizing Windows Runtime components process specific data structures that trigger undefined behavior in memory allocation and deallocation routines. Attackers can leverage this weakness by crafting malicious inputs or manipulating application state to cause memory corruption that leads to privilege escalation. The vulnerability is classified as a use-after-free condition where freed memory objects are accessed by subsequent operations, potentially allowing arbitrary code execution. This type of vulnerability maps directly to CWE-416, which defines the weakness of freeing memory twice or accessing freed memory, and aligns with ATT&CK technique T1068 which covers exploit for privilege escalation.
The operational impact of CVE-2021-1650 extends beyond simple privilege escalation as it provides attackers with comprehensive system control capabilities. Once successfully exploited, adversaries gain access to all system resources, can modify or delete critical files, establish persistence mechanisms, and potentially move laterally within network environments. The vulnerability's exploitation requires minimal privileges initially, making it particularly dangerous for enterprise environments where standard user accounts are common. Organizations may experience complete system compromise, data exfiltration, and persistent backdoor access. The vulnerability's presence in core Windows libraries means that exploitation can occur through various attack vectors including malicious applications, web-based attacks, or compromised software installations. Security teams must recognize that this vulnerability can be exploited through both direct application-based attacks and through supply chain compromises targeting legitimate software that utilizes the affected Windows Runtime components.
Mitigation strategies for CVE-2021-1650 should prioritize immediate patch deployment through Microsoft's regular security updates, specifically the February 2021 security bulletin. Organizations should implement network segmentation and application whitelisting to limit potential attack surfaces where vulnerable applications might be executed. Monitoring for suspicious process behavior and memory access patterns can help detect exploitation attempts. System administrators should ensure that all Windows systems are maintained with current security patches and that automatic update mechanisms are properly configured. Additional defensive measures include implementing least privilege access controls, conducting regular vulnerability assessments, and maintaining updated threat intelligence feeds to monitor for exploitation activity. The vulnerability demonstrates the critical importance of maintaining up-to-date system components and highlights the risks associated with legacy software that may not receive timely security updates, making comprehensive patch management a fundamental security requirement for all Windows environments.