CVE-2021-41339 in Windows
Summary
by MITRE • 10/13/2021
Microsoft DWM Core Library Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/15/2021
The Microsoft DWM Core Library Elevation of Privilege Vulnerability represents a critical security flaw within the Windows Display Manager component that governs graphical rendering and window management operations. This vulnerability resides in the Desktop Window Manager core library which handles essential display functions including window composition, visual effects, and graphics processing. The flaw allows an attacker with low-privilege user access to escalate their privileges to system level, potentially enabling complete system compromise. The vulnerability specifically affects Windows 10 versions and Windows Server 2016 and 2019 operating systems where the DWM service runs with elevated privileges.
Technical exploitation of this vulnerability leverages improper validation of input parameters within the DWM core library functions. The flaw manifests when the system processes certain graphical operations that involve memory manipulation and resource allocation. Attackers can craft malicious input sequences that trigger memory corruption within the DWM process, allowing them to manipulate kernel-level memory structures. This memory corruption leads to arbitrary code execution within the context of the SYSTEM account, bypassing standard privilege boundaries. The vulnerability is classified as a heap-based buffer overflow that occurs during the processing of display-related commands, particularly those involving window management and graphics rendering operations.
The operational impact of CVE-2021-41339 is severe and far-reaching across enterprise environments. Organizations running affected Windows versions face significant risk of unauthorized system compromise, data exfiltration, and persistent backdoor installation. The vulnerability can be exploited through various attack vectors including malicious web content, compromised email attachments, or malicious software installations that trigger the problematic display rendering code. Once escalated to SYSTEM privileges, attackers gain unrestricted access to all system resources including user credentials, sensitive data, network communications, and the ability to install additional malware or rootkits. This makes the vulnerability particularly dangerous in environments where privileged accounts are frequently used or where sensitive information is stored.
Mitigation strategies for this vulnerability require immediate patch deployment through Microsoft's regular security updates, specifically targeting the Windows 10 and Windows Server versions affected by the flaw. Organizations should implement comprehensive monitoring for suspicious display-related process activities and memory access patterns that could indicate exploitation attempts. Security teams should also consider implementing application control policies that restrict execution of untrusted graphical content and ensure proper privilege separation between user and system processes. The vulnerability aligns with CWE-121 heap-based buffer overflow classification and represents a technique that could be mapped to ATT&CK tactic T1068 privilege escalation through local exploitation methods. Additionally, network segmentation and privileged access management controls should be strengthened to limit potential lateral movement once a system is compromised, as the elevated privileges gained through this vulnerability provide attackers with complete system control capabilities.