CVE-2025-24061: Windows 10 1507 MOTW Auth Bypass Flaw

CVE-2025-24061 Overview

CVE-2025-24061 is a security feature bypass vulnerability in Windows Mark of the Web (MOTW) that allows an unauthorized attacker to bypass critical security protections locally. The Mark of the Web is a Windows security mechanism that tags files downloaded from the internet with a special NTFS alternate data stream (Zone.Identifier), enabling Windows to apply additional security restrictions such as SmartScreen checks and Protected View in Office applications. This vulnerability undermines these protective measures, potentially allowing malicious files to execute without the standard security warnings that would normally alert users to potential threats.

Critical Impact

Attackers can bypass Windows MOTW security protections, enabling downloaded malicious files to execute without security warnings or SmartScreen scanning, significantly increasing the risk of successful malware delivery.

Affected Products

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

Discovery Timeline

• March 11, 2025 - CVE-2025-24061 published to NVD
• July 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-24061

Vulnerability Analysis

This vulnerability stems from a protection mechanism failure (CWE-693) in how Windows handles and propagates the Mark of the Web security attribute. When files are downloaded from the internet or received from untrusted sources, Windows applies the MOTW by setting the Zone.Identifier alternate data stream to indicate the file's origin. This metadata is critical for enabling security features like SmartScreen Application Reputation checks, Microsoft Office Protected View, and execution warnings for downloaded executables.

The flaw allows attackers to craft files or employ techniques that cause Windows to fail to properly apply, preserve, or enforce the MOTW designation. This could occur through manipulation of archive extraction processes, exploitation of specific file handling routines, or other mechanisms that cause the security attribute to be dropped or ignored.

Root Cause

The root cause is classified as CWE-693: Protection Mechanism Failure. This indicates that the MOTW security mechanism, which is designed to protect users from untrusted downloaded content, fails to operate as intended under certain conditions. The failure likely exists in the file handling or archive extraction components of Windows that are responsible for preserving and propagating security attributes from parent containers to extracted files.

Attack Vector

The attack vector is local, requiring user interaction to be exploited. A typical attack scenario involves:

1. An attacker crafting a malicious file or archive designed to trigger the MOTW bypass condition
2. Delivering the file to a victim through email, malicious websites, or other distribution methods
3. The victim downloading and interacting with the file (e.g., extracting an archive)
4. The MOTW protection failing to be applied or enforced on the extracted malicious content
5. The malicious payload executing without SmartScreen warnings or other MOTW-based security protections

This vulnerability is particularly concerning because MOTW bypasses are frequently weaponized by threat actors to deliver malware. Without the MOTW tag, malicious Office documents open without Protected View restrictions, and executables run without SmartScreen prompts, dramatically increasing the likelihood of successful compromise.

Detection Methods for CVE-2025-24061

Indicators of Compromise

• Files extracted from archives that lack the expected Zone.Identifier alternate data stream despite being downloaded from the internet
• Executable files or Office documents running without triggering SmartScreen warnings in environments where such checks should occur
• Unusual archive file types or structures in user download directories that may be designed to exploit MOTW handling flaws

Detection Strategies

• Monitor for execution of files from user download directories that lack Zone.Identifier alternate data streams using PowerShell or EDR tooling
• Implement behavioral detection for suspicious file extraction activities, particularly involving nested archives or unusual archive formats
• Enable enhanced logging for Windows Defender SmartScreen events to identify cases where downloaded files bypass reputation checks
• Deploy endpoint detection rules that flag Office documents opening in edit mode from locations where Protected View should apply

Monitoring Recommendations

• Configure SentinelOne policies to monitor and alert on MOTW-related anomalies and execution of unmarked files from untrusted locations
• Enable Windows Security event logging for SmartScreen and Protected View bypass attempts
• Implement file system monitoring to detect files downloaded from browsers that are missing Zone.Identifier streams
• Regularly audit endpoints for evidence of MOTW manipulation techniques used in malware campaigns

How to Mitigate CVE-2025-24061

Immediate Actions Required

• Apply the Microsoft security updates for CVE-2025-24061 immediately across all affected Windows systems
• Prioritize patching for user workstations that regularly download files from the internet or receive email attachments
• Review and restrict users' ability to extract archives from untrusted sources until patches are deployed
• Enable additional endpoint protection controls such as application whitelisting in high-risk environments

Patch Information

Microsoft has released security updates addressing this vulnerability. Detailed patch information and download links are available in the Microsoft Security Response Center advisory. Organizations should apply the appropriate cumulative update for their Windows version through Windows Update, WSUS, or Microsoft Update Catalog.

Workarounds

• Implement strict email gateway filtering to block potentially malicious archive file types until patches are applied
• Configure Group Policy to enforce SmartScreen checks and block execution of unrecognized applications where feasible
• Use application control solutions like Windows Defender Application Control (WDAC) or AppLocker to restrict execution of untrusted files
• Educate users about the increased risk of opening downloaded files and encourage reporting of suspicious content

# PowerShell command to check if a file has the Mark of the Web attribute
Get-Item -Path "C:\Path\To\File.exe" -Stream Zone.Identifier -ErrorAction SilentlyContinue

# PowerShell command to audit files lacking MOTW in the Downloads folder
Get-ChildItem -Path "$env:USERPROFILE\Downloads" -Recurse | ForEach-Object {
    $stream = Get-Item -Path $_.FullName -Stream Zone.Identifier -ErrorAction SilentlyContinue
    if (-not $stream) {
        Write-Output "Missing MOTW: $($_.FullName)"
    }
}