CVE-2025-21337: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-21337 Overview

CVE-2025-21337 is a Windows NTFS Elevation of Privilege Vulnerability affecting a wide range of Microsoft Windows operating systems. This vulnerability exists within the NTFS file system component and allows an authenticated local attacker to potentially gain access to sensitive information through improper access control mechanisms.

Critical Impact

Local attackers with low privileges can exploit this NTFS vulnerability to read sensitive data, potentially leading to information disclosure across affected Windows systems.

Affected Products

• Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
• Microsoft Windows 11 (versions 22H2, 23H2, 24H2)
• Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2022 23H2, 2025

Discovery Timeline

• 2025-02-11 - CVE CVE-2025-21337 published to NVD
• 2025-02-28 - Last updated in NVD database

Technical Details for CVE-2025-21337

Vulnerability Analysis

This vulnerability stems from improper access control (CWE-284) within the Windows NTFS file system driver. The flaw allows an authenticated user with low-level privileges to bypass intended access restrictions and read sensitive information from the file system that should not be accessible to them.

The attack requires local access to the target system, meaning an attacker must already have some level of authentication to the machine. Once authenticated, they can exploit the improper access control to access confidential data stored on NTFS volumes. While the vulnerability does not permit code execution or system modification, the information disclosure could expose sensitive data such as configuration files, cached credentials, or other protected information.

Root Cause

The root cause of CVE-2025-21337 is classified as CWE-284 (Improper Access Control). The NTFS driver fails to properly validate access permissions under certain conditions, allowing authenticated users to read data beyond their authorized scope. This improper enforcement of access controls creates a path for information disclosure when a local attacker crafts specific file system requests that bypass the intended security checks.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have authenticated access to the target Windows system. The exploitation scenario involves:

1. An attacker gains low-privileged access to a Windows system (through legitimate credentials or prior compromise)
2. The attacker interacts with the NTFS file system in a manner that triggers the improper access control condition
3. The NTFS driver fails to properly enforce access restrictions
4. The attacker gains read access to data they should not be authorized to view

This is a low-complexity attack that does not require user interaction once the attacker has local system access.

Detection Methods for CVE-2025-21337

Indicators of Compromise

• Unusual file system access patterns from low-privileged user accounts
• Unexpected read operations against protected system files or directories
• Anomalous NTFS driver behavior or error events in Windows Event logs
• Access attempts to sensitive directories by non-administrative users

Detection Strategies

• Monitor Windows Security Event logs for access control failures (Event ID 4656, 4663) involving unusual source accounts
• Deploy endpoint detection solutions to identify abnormal file system access patterns
• Implement file integrity monitoring on sensitive directories to detect unauthorized access
• Use behavioral analytics to detect privilege escalation attempts and unusual data access patterns

Monitoring Recommendations

• Enable advanced auditing for Object Access events on sensitive NTFS volumes
• Configure SentinelOne Singularity to monitor for NTFS-related suspicious activities
• Implement alerts for bulk file read operations from low-privileged accounts
• Review authentication logs for lateral movement that may precede exploitation

How to Mitigate CVE-2025-21337

Immediate Actions Required

• Apply the latest Windows security updates from Microsoft immediately
• Review and restrict local user access to sensitive directories and files
• Implement the principle of least privilege for all user accounts
• Enable advanced auditing to detect potential exploitation attempts

Patch Information

Microsoft has released security patches addressing this vulnerability. Organizations should apply the appropriate updates for their Windows versions through Windows Update, Windows Server Update Services (WSUS), or the Microsoft Update Catalog. For detailed patch information and download links, refer to the Microsoft Security Update Guide for CVE-2025-21337.

Workarounds

• Restrict local access to systems containing sensitive data until patches can be applied
• Implement additional access controls and file system permissions on sensitive directories
• Use BitLocker or other encryption solutions to protect data at rest
• Monitor and limit the scope of user permissions on affected systems

# Enable Object Access Auditing via Group Policy
auditpol /set /subcategory:"File System" /success:enable /failure:enable

# Review current file system permissions on sensitive directories
icacls "C:\sensitive_directory" /T

# Enable advanced security auditing
auditpol /set /subcategory:"Handle Manipulation" /success:enable /failure:enable