CVE-2021-1663 in Windows
Summary
by MITRE • 01/13/2021
Windows Projected File System FS Filter Driver Information Disclosure Vulnerability This CVE ID is unique from CVE-2021-1670, CVE-2021-1672.
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Analysis
by VulDB Data Team • 10/09/2024
The Windows Projected File System FS Filter Driver Information Disclosure Vulnerability represents a critical security flaw within Microsoft's file system filtering infrastructure that affects Windows operating systems. This vulnerability specifically targets the projected file system component that enables applications to present virtual file system content to users while maintaining the illusion of a physical file structure. The issue stems from improper handling of kernel-mode memory operations within the fsfilter driver that manages projected file system interactions, creating potential information disclosure pathways that could be exploited by malicious actors.
This vulnerability manifests through improper validation of input parameters and insufficient memory management within the kernel-level driver components responsible for projected file system operations. The flaw allows unauthorized access to kernel memory structures and potentially sensitive information that should remain protected within the operating system's privileged execution environment. The technical implementation involves inadequate boundary checking and memory access controls that permit attackers to read data from kernel memory regions that should be restricted to legitimate system processes. According to CWE classification, this vulnerability maps to CWE-200 Information Exposure, with specific characteristics aligned with CWE-125 Out-of-bounds Read and CWE-772 Missing Release of Resource after Effective Lifetime, as the driver fails to properly manage memory resources during projected file system operations.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially enabling attackers to extract sensitive kernel memory contents including system credentials, encryption keys, or other confidential data that could be leveraged for further exploitation. Attackers could potentially use this information to escalate privileges or conduct more sophisticated attacks against the target system. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern for enterprise environments. Security researchers have noted that the flaw could be particularly dangerous when combined with other exploits, as the leaked information could provide attackers with critical system insights for privilege escalation attacks. This vulnerability aligns with ATT&CK technique T1003 Credential Dumping, as the information disclosure could potentially expose credential material stored in kernel memory.
Mitigation strategies for this vulnerability require immediate patch deployment from Microsoft, as the company released security updates addressing the specific memory handling issues within the fsfilter driver. Organizations should prioritize patch management processes to ensure all affected systems receive the necessary security updates. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation attempts, while monitoring for unusual memory access patterns or file system operations could aid in early detection of exploitation attempts. System administrators should also consider implementing enhanced logging and monitoring of kernel-mode operations to detect potential abuse of this vulnerability. The vulnerability demonstrates the importance of proper kernel memory management and input validation in preventing information disclosure attacks that could compromise entire operating system environments.