Windows security researchers have identified a critical vulnerability in the NTFS file system, designated as CVE-2025-24992, which could allow attackers to exploit a buffer over-read condition. This flaw poses a significant risk to systems running Windows 10, 11, and Windows Server editions, potentially leading to information disclosure or system crashes.

What is CVE-2025-24992?

CVE-2025-24992 is a buffer over-read vulnerability in the NTFS (New Technology File System) driver. A buffer over-read occurs when a program reads more data from a buffer than it should, potentially exposing sensitive information stored in adjacent memory locations. Unlike buffer overflows, which write beyond allocated memory, over-reads focus on unauthorized data access.

How Does This Vulnerability Work?

The flaw arises when the NTFS driver improperly handles specially crafted files or directories. An attacker could exploit this by:

  • Creating a malicious NTFS file system structure
  • Tricking a user into mounting a compromised drive
  • Exploiting a remote share with a malformed file

Once triggered, the vulnerability allows reading kernel memory, which may contain sensitive data like encryption keys, passwords, or system configurations.

Impact and Severity

Microsoft has rated this vulnerability as Important (not Critical) because:

  • It requires local access or specific user interaction
  • Successful exploitation doesn't directly allow code execution
  • Modern Windows mitigations like ASLR make exploitation harder

However, the risks include:

  • Information disclosure from kernel memory
  • Potential system instability or crashes
  • Possible chaining with other vulnerabilities for greater impact

Affected Systems

The vulnerability affects:

  • Windows 10 versions 1809 and later
  • Windows 11 all versions
  • Windows Server 2019 and 2022

Mitigation and Protection

Microsoft has released patches through Windows Update. Users should:

  1. Apply the latest security updates immediately
  2. Enable Controlled Folder Access for additional protection
  3. Restrict access to untrusted NTFS volumes
  4. Monitor for suspicious file system activities

For enterprises, Microsoft recommends:

  • Deploying updates through WSUS or Configuration Manager
  • Implementing application whitelisting
  • Using Windows Defender Attack Surface Reduction rules

Technical Deep Dive

The vulnerability stems from how ntfs.sys handles certain file attributes. When processing an extended attribute with a malformed length field, the driver fails to properly validate buffer boundaries before reading data. This can be represented as:

// Pseudocode of vulnerable function
void ProcessAttribute(PATTRIBUTE attr) {
    char buffer[256];
    // Missing proper length validation
    memcpy(buffer, attr->data, attr->length); // Potential over-read
}

Detection and Indicators

System administrators can look for:

  • Unexpected system crashes with bugcheck code 0x50 (PAGE_FAULT_IN_NONPAGED_AREA)
  • Security logs showing suspicious file system operations
  • Performance Monitor counters showing unusual NTFS activity

Historical Context

This isn't the first NTFS vulnerability:

  • 2021: CVE-2021-31956 - NTFS elevation of privilege
  • 2019: CVE-2019-0709 - NTFS denial of service
  • 2017: CVE-2017-11780 - NTFS information disclosure

These recurring issues highlight the complexity of file system security.

Best Practices for Prevention

Beyond patching, organizations should:

  • Implement the principle of least privilege
  • Use virtualization for risky file operations
  • Regularly audit file server permissions
  • Consider disabling NTFS extended attributes if unused

Future Outlook

Microsoft continues to harden NTFS with:

  • Improved bounds checking
  • Better fuzzing of file system components
  • Integration with Windows Defender for file system monitoring

Security researchers recommend treating file system drivers as high-risk components deserving special attention in security architectures.