CVE-2024-30050: Windows 10 1507 Auth Bypass Vulnerability

CVE-2024-30050 Overview

CVE-2024-30050 is a security feature bypass vulnerability affecting the Windows Mark of the Web (MotW) mechanism. The Mark of the Web is a critical Windows security feature that tags files downloaded from the internet or received via email with a special NTFS alternate data stream (ADS) attribute called Zone.Identifier. This marking triggers additional security prompts and restrictions when users attempt to open potentially dangerous files, including SmartScreen warnings and Protected View in Microsoft Office applications.

This vulnerability allows attackers to craft malicious files that bypass the MotW security checks, potentially enabling them to deliver malware that executes without triggering the standard Windows security warnings that would normally alert users to downloaded content from untrusted sources.

Critical Impact

Successful exploitation allows attackers to bypass Windows SmartScreen and Protected View defenses, enabling malicious files to execute without user security warnings across all supported Windows versions.

Affected Products

• Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
• Microsoft Windows 11 (versions 21H2, 22H2, 23H2)
• Microsoft Windows Server 2008 SP2/R2 SP1
• Microsoft Windows Server 2012/R2
• Microsoft Windows Server 2016
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022/23H2

Discovery Timeline

• May 14, 2024 - CVE-2024-30050 published to NVD
• January 8, 2025 - Last updated in NVD database

Technical Details for CVE-2024-30050

Vulnerability Analysis

The Mark of the Web bypass vulnerability stems from improper handling of certain file types or archive formats by Windows security mechanisms. When Windows encounters downloaded files, it normally applies the Zone.Identifier alternate data stream to mark them as originating from an untrusted zone (typically Zone 3 for the Internet). This triggers SmartScreen filtering and other protective measures when the file is executed.

The vulnerability allows specially crafted files to circumvent this tagging mechanism, resulting in downloaded content being treated as if it originated locally. This defeats a fundamental trust boundary in Windows security architecture, which classifies weakly under CWE-693 (Protection Mechanism Failure).

When MotW is bypassed, malicious executables, Office documents with macros, and script files can execute without the standard security dialogs that would warn users about potential risks. This significantly increases the success rate of phishing campaigns and drive-by download attacks.

Root Cause

The root cause relates to insufficient validation or handling of specific file characteristics that should trigger the Mark of the Web tagging mechanism. Windows fails to properly propagate or enforce the MotW attribute in certain scenarios, creating a gap in the trust boundary enforcement between internet-sourced and local content.

Attack Vector

The attack vector is network-based, requiring user interaction. An attacker would typically:

1. Craft a malicious file designed to evade MotW tagging
2. Host the file on a malicious website or deliver it via phishing email
3. Trick the user into downloading and opening the file
4. The file executes without SmartScreen warnings or Protected View restrictions

The exploitation mechanism involves specific file formatting or archive techniques that cause Windows to improperly handle the Zone.Identifier stream. Technical details regarding the specific bypass method should be obtained from the Microsoft Security Update Guide.

Detection Methods for CVE-2024-30050

Indicators of Compromise

• Downloaded files executing without expected SmartScreen prompts or Protected View activation
• Unusual file types or archive formats that extract without preserving MotW attributes
• Endpoint telemetry showing execution of files lacking Zone.Identifier alternate data streams despite network origin
• User reports of downloaded Office documents opening in editing mode rather than Protected View

Detection Strategies

• Monitor for executable launches where the file's Zone.Identifier ADS is absent despite recent download activity
• Implement application control policies that restrict execution of unsigned or untrusted binaries regardless of MotW status
• Deploy behavioral detection for common post-exploitation activities following execution of unmarked downloaded content
• Correlate proxy/firewall logs with endpoint execution events to identify downloads that bypass MotW

Monitoring Recommendations

• Enable Windows Security event logging for file execution and SmartScreen bypass events
• Configure EDR solutions to alert on execution of files downloaded within recent timeframes that lack MotW markings
• Monitor for archive extraction operations followed by immediate execution of contained files
• Track execution of files from common download locations (Downloads, %TEMP%, browser cache directories)

How to Mitigate CVE-2024-30050

Immediate Actions Required

• Apply the May 2024 security updates from Microsoft immediately to all affected Windows systems
• Enable Attack Surface Reduction (ASR) rules that block execution of potentially obfuscated scripts and untrusted executables
• Review and strengthen email attachment filtering policies to block suspicious file types at the gateway
• Implement application whitelisting where feasible to reduce reliance on MotW as a primary defense

Patch Information

Microsoft released security updates addressing this vulnerability as part of the May 2024 Patch Tuesday release cycle. Organizations should apply the appropriate cumulative update for their Windows version. Detailed patch information and download links are available in the Microsoft Security Update Guide for CVE-2024-30050.

Workarounds

• Enable Windows Defender Application Control (WDAC) or AppLocker policies to restrict execution to trusted applications
• Configure Group Policy to block execution of files from internet zones regardless of MotW status using Zone-based restrictions
• Implement strict macro policies in Microsoft Office to disable macros in documents from internet sources
• Deploy additional email security controls to scan and quarantine suspicious attachments before delivery

# PowerShell: Check Zone.Identifier on a file to verify MotW presence
Get-Content -Path "C:\Users\username\Downloads\suspicious_file.exe" -Stream Zone.Identifier

# Enable ASR rule to block executable files from running unless they meet prevalence, age, or trusted list criteria
Set-MpPreference -AttackSurfaceReductionRules_Ids 01443614-cd74-433a-b99e-2ecdc07bfc25 -AttackSurfaceReductionRules_Actions Enabled