CVE-2024-38180: Windows 10 1507 Auth Bypass Vulnerability

CVE-2024-38180 Overview

CVE-2024-38180 is a Windows SmartScreen security feature bypass vulnerability affecting a broad range of Microsoft Windows client and server operating systems. Microsoft disclosed the issue on August 13, 2024 as part of its monthly security update cycle. The flaw allows attackers to circumvent SmartScreen's reputation-based protections, enabling delivery of unsigned or low-reputation payloads without triggering the expected warning prompts. Exploitation requires user interaction, typically opening a crafted file or link, and operates over a network attack vector. The vulnerability is mapped to [CWE-693: Protection Mechanism Failure] and carries an EPSS probability of 6.54% (91.31 percentile), indicating elevated exploitation interest relative to most published CVEs.

Critical Impact
Successful exploitation bypasses Windows SmartScreen, allowing attacker-controlled content to execute without SmartScreen warnings and resulting in high impact to confidentiality, integrity, and availability.

Affected Products

Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 21H2, 22H2, 23H2, 24H2)
Microsoft Windows Server 2008, 2012, 2012 R2, 2016, 2019, 2022, and 2022 23H2

Discovery Timeline

2024-08-13 - CVE-2024-38180 published to the National Vulnerability Database
2024-08-13 - Microsoft publishes security advisory and patch through the Microsoft Security Update Guide
2024-08-16 - Last updated in NVD database

Technical Details for CVE-2024-38180

Vulnerability Analysis

Windows SmartScreen is the reputation and Mark-of-the-Web (MotW) enforcement component that inspects downloaded files, scripts, and shortcuts before they execute. CVE-2024-38180 is classified as a security feature bypass, meaning attackers can circumvent the protection mechanism rather than corrupt memory or escalate privileges directly. When SmartScreen fails to evaluate or display its warning UI for a crafted artifact, the user is presented with what appears to be a trusted file. This removes the final barrier between attacker-staged content and code execution under the user's context. The bypass is particularly relevant in phishing and drive-by download chains where the initial access vector relies on the user opening a downloaded payload.

Root Cause

The root cause lies in SmartScreen's evaluation logic failing to apply or enforce reputation checks for specific file types or content presentations. As a CWE-693 protection mechanism failure, the underlying file delivery primitive is not vulnerable on its own; the gap is in SmartScreen suppressing the security prompt that would otherwise alert the user. Microsoft has not published deeper technical detail beyond the advisory.

Attack Vector

The attack is network-based and requires user interaction. A typical chain involves an attacker hosting a crafted file on a website, sending it via email, or staging it on a file share. When the victim opens the file, SmartScreen does not display the expected unrecognized-file warning, and the payload executes with the user's privileges. No prior authentication on the target is required. Because no public proof-of-concept or in-the-wild exploitation has been confirmed against this CVE, defenders should treat it as a likely component of multi-stage social engineering campaigns rather than a standalone remote exploit.

Detection Methods for CVE-2024-38180

Indicators of Compromise

Execution of recently downloaded binaries, scripts, or shortcut files that lack a SmartScreen prompt in user telemetry.
Files with missing or stripped Zone.Identifier alternate data streams despite originating from the internet.
Process trees showing browsers, email clients, or archive utilities spawning unsigned executables shortly after a download event.

Detection Strategies

Hunt for child processes of explorer.exe, outlook.exe, chrome.exe, msedge.exe, and archive tools where the child is an unsigned executable launched from %TEMP%, %APPDATA%, or the Downloads directory.
Correlate web download events with subsequent process creation to identify cases where SmartScreen should have, but did not, intervene.
Monitor for tampering with Mark-of-the-Web alternate data streams on user-writable paths.

Monitoring Recommendations

Enable and forward Microsoft-Windows-SmartScreen operational and Windows Defender SmartScreen event logs to a centralized SIEM.
Track Sysmon Event ID 15 (FileCreateStreamHash) to validate that MotW is being applied to downloaded content.
Baseline expected SmartScreen prompt rates and alert on statistically significant decreases per endpoint group.

How to Mitigate CVE-2024-38180

Immediate Actions Required

Apply the August 2024 Microsoft security updates referenced in the Microsoft Security Update Guide to all affected Windows client and server builds.
Prioritize patching internet-facing user workstations, jump hosts, and Remote Desktop Services hosts where users open external files.
Audit endpoints to confirm SmartScreen is enabled for File Explorer and Microsoft Edge through Group Policy or Intune.

Patch Information

Microsoft released cumulative updates addressing CVE-2024-38180 on August 13, 2024 across all supported Windows 10, Windows 11, and Windows Server branches listed in the affected products table. Refer to the vendor advisory for build-specific KB article numbers and offline update packages.

Workarounds

Enforce attachment and download filtering at the email gateway and web proxy to block high-risk file types (.lnk, .iso, .vhd, .scr, unsigned .exe) where business need does not require them.
Use Windows Defender Application Control (WDAC) or AppLocker to restrict execution of unsigned binaries from user-writable directories.
Deliver targeted user awareness reminders about opening files from unfamiliar senders, since the vulnerability eliminates the SmartScreen warning that users are trained to heed.

bash

# Verify SmartScreen is enabled for Explorer and Edge via PowerShell
Get-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\System' -Name 'EnableSmartScreen' -ErrorAction SilentlyContinue
Get-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Edge' -Name 'SmartScreenEnabled' -ErrorAction SilentlyContinue

# Enforce SmartScreen 'Block' mode for Explorer
New-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\System' -Name 'ShellSmartScreenLevel' -Value 'Block' -PropertyType String -Force