CVE-2021-41367 in Windows
Summary
by MITRE • 11/10/2021
NTFS Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-41370, CVE-2021-42283.
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Analysis
by VulDB Data Team • 11/11/2021
The NTFS Elevation of Privilege Vulnerability identified as CVE-2021-41367 represents a critical security flaw within the Windows NT File System implementation that allows authenticated attackers to escalate their privileges from standard user level to system level execution. This vulnerability specifically targets the way NTFS handles certain file system operations and metadata processing, creating an exploitable condition that bypasses normal access controls and privilege boundaries. The flaw exists in the kernel-mode components responsible for NTFS file system operations, making it particularly dangerous as it operates at the core of Windows file system functionality. Unlike other related vulnerabilities such as CVE-2021-41370 which targets different aspects of the file system or CVE-2021-42283 which affects Kerberos authentication, this vulnerability is specifically focused on NTFS privilege escalation mechanisms and demonstrates a fundamental weakness in how the operating system manages file system permissions and access control lists. The vulnerability's impact extends beyond simple file access restrictions as it provides attackers with the ability to execute arbitrary code with elevated privileges, potentially leading to complete system compromise.
The technical exploitation of CVE-2021-41367 leverages a flaw in the NTFS file system driver's handling of specific file operations that involve privilege checking and access validation. Attackers can craft malicious file system operations that manipulate the way the system evaluates access permissions, particularly when dealing with file creation, modification, and access control list operations. The vulnerability stems from improper validation of file system metadata and insufficient boundary checks during file operations that should normally be restricted to privileged processes only. This flaw creates a condition where a standard user can manipulate file system structures in ways that bypass normal security checks, effectively allowing them to perform operations that should be restricted to administrators or system processes. The exploitation process typically involves creating specific file system conditions that trigger the vulnerable code path, often through carefully constructed file operations that exploit the underlying flaw in how NTFS validates access permissions. This type of vulnerability is classified under CWE-264 as "Permissions, Privileges, and Access Controls" and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" by demonstrating how attackers can leverage system-level vulnerabilities to gain elevated access rights.
The operational impact of CVE-2021-41367 is severe and far-reaching within enterprise environments that rely on Windows systems for their core operations. Organizations running vulnerable Windows versions face significant risk of unauthorized access to sensitive data, system compromise, and potential lateral movement within their network infrastructure. The vulnerability's exploitation can lead to complete system takeover, allowing attackers to establish persistent backdoors, exfiltrate confidential information, or deploy additional malware. Security teams must recognize that this vulnerability can be exploited remotely or locally, making it particularly dangerous in environments where users have legitimate access to systems but could be compromised through social engineering or other attack vectors. The risk assessment for this vulnerability should consider not only the immediate privilege escalation capabilities but also the potential for further exploitation once an attacker has gained system-level access. Organizations should be particularly concerned about systems that handle sensitive data or serve as domain controllers, as the privilege escalation could enable attackers to compromise entire domain environments. This vulnerability also impacts the integrity of the Windows security model and can undermine other security controls that depend on proper privilege separation and access control enforcement.
Mitigation strategies for CVE-2021-41367 should include immediate deployment of Microsoft security patches and updates to address the underlying NTFS implementation flaw. Organizations must ensure that all Windows systems are updated with the latest security patches, particularly those addressing NTFS file system vulnerabilities. Network segmentation and access control measures should be implemented to limit user access to critical systems and prevent lateral movement in case of exploitation. Security monitoring should focus on unusual file system operations, particularly those involving access control list modifications or privilege-related file operations that could indicate exploitation attempts. System administrators should implement principle of least privilege configurations and regularly audit file system permissions to identify potential anomalies. The vulnerability also highlights the importance of maintaining up-to-date security awareness training for users, as social engineering attacks that lead to initial access are often necessary prerequisites for exploitation. Organizations should conduct vulnerability assessments to identify systems that may be running older Windows versions that are not receiving security updates, as these systems may be particularly vulnerable to this and related NTFS-based attacks. Additionally, implementing behavioral monitoring solutions that can detect anomalous file system operations and access patterns can provide early warning of potential exploitation attempts. Regular security audits and penetration testing should include assessment of file system security controls to ensure that privilege escalation mechanisms are properly functioning and that access controls are effectively enforced across all Windows environments.