CVE-2023-21767 in Windows
Summary
by MITRE • 01/11/2023
Windows Overlay Filter Elevation of Privilege Vulnerability.
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Analysis
by VulDB Data Team • 09/24/2025
This vulnerability resides within the Windows Overlay Filter driver component, which serves as a critical subsystem for managing file system operations and overlay functionality in Windows operating systems. The flaw represents a privilege escalation weakness that allows attackers to elevate their execution privileges from standard user level to system level, bypassing standard security controls. The vulnerability specifically affects the handling of kernel-mode operations within the overlay filter mechanism, creating an opportunity for malicious code execution with elevated privileges.
The technical root cause stems from improper input validation and memory management within the kernel driver interfaces. Attackers can exploit this weakness by crafting specific file system operations that trigger buffer overflows or use-after-free conditions in the overlay filter component. This flaw operates at the kernel level, making it particularly dangerous as it can be leveraged to bypass standard Windows security features including User Access Control, code integrity checks, and privilege separation mechanisms. The vulnerability manifests when legitimate system processes interact with the overlay filter driver, creating a pathway for malicious payloads to execute with system-level privileges.
Operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to establish persistent access, modify system files, install malicious software, and potentially compromise entire network infrastructures. The attack surface is particularly concerning given that the overlay filter is integral to Windows file system operations, making exploitation possible through common user activities such as file access, network operations, and system interactions. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow and CWE-122 Heap-based Buffer Overflow classifications, representing a classic kernel-mode privilege escalation vector that can be exploited across multiple Windows versions including windows 10 and windows server 2019.
Mitigation strategies must encompass immediate patch deployment from microsoft security updates, which address the underlying driver vulnerabilities through proper input validation and memory management corrections. System administrators should implement additional security controls including kernel mode exploit prevention tools, enhanced monitoring of kernel driver activities, and regular security assessments of file system operations. The vulnerability demonstrates characteristics consistent with attack techniques documented in the mitre att&ck framework under privilege escalation tactics, specifically targeting kernel-mode exploitation methods. Organizations should also consider implementing least-privilege principles and maintaining robust endpoint detection and response capabilities to detect anomalous kernel activities that may indicate exploitation attempts. Regular security training for system administrators and developers regarding kernel-mode security considerations remains essential for comprehensive defense against such sophisticated vulnerabilities.