Windows Ancillary Function Driver (afd.sys) Use-After-Free Privilege Escalation Vulnerability (CVE-2024-38193) Technical Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTMost versions of Windows 10, 11, and Windows Server 2008 through 2022
Local attackers can exploit kernel memory corruption to execute arbitrary code with SYSTEM privileges
Immediately apply the Microsoft August 2024 security updates and monitor for unauthorized local account activities
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to apply the official cumulative security updates provided by Microsoft. You can force the installation of these updates using PowerShell.
# Install and import the PSWindowsUpdate module to apply pending security patches
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck -Verbose
Get-WindowsUpdate -Category 'Security Updates' -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
Because this is a kernel-level driver vulnerability, direct workarounds are highly limited. Organizations should restrict local execution capabilities by enforcing AppLocker or Windows Defender Application Control (WDAC) to prevent unauthorized binaries from running and attempting exploitation.
# Enable and start the Application Identity service required for AppLocker policies
Set-Service -Name 'AppIDSvc' -StartupType Automatic
Start-Service -Name 'AppIDSvc'
Write-Output 'AppLocker service has been started to enforce application execution control policies.'3. Log Audit & IoC Verification Commands
Verify the patch level of the target system by checking the file version of the afd.sys driver.
# Retrieve the file version of afd.sys to verify patch status
$DriverPath = '$env:SystemRoot\System32\drivers\afd.sys'
if (Test-Path $DriverPath) {
$VersionInfo = (Get-Item $DriverPath).VersionInfo.FileVersion
Write-Output 'Current afd.sys version: ' $VersionInfo
Write-Output 'Verify this version against the Microsoft August 2024 Patch Tuesday release notes for your OS build.'
} else {
Write-Error 'afd.sys driver file was not found in the standard directory.'
}Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2024-38193) is a Use-After-Free (UAF, CWE-416) flaw residing in the Windows Ancillary Function Driver (afd.sys), which serves as the entry point for Windows Sockets (WinSock). The root cause lies in how afd.sys manages socket connection states and internal buffer objects. When processing specific Input/Output Control (IOCTL) requests, the driver fails to properly nullify or invalidate pointers to memory blocks that have already been freed, leading to subsequent dangling pointer dereferences.
2. Exploitation Mechanics & Attack Scenario
An attacker with local, low-privilege access on the target system initiates the exploit by sending crafted IOCTL requests to the afd.sys device object. By triggering the premature release of specific socket resources and leveraging kernel pool feng shui techniques, the attacker reclaims the freed memory space with controlled payload data. When the driver subsequently attempts to access the previously freed object, it executes the attacker-controlled data within the kernel context, resulting in local privilege escalation to SYSTEM. This vulnerability has been actively exploited in the wild and is cataloged in CISA's KEV.
3. Infrastructure & Business Impact
Local Privilege Escalation (EoP) vulnerabilities pose a severe threat in multi-tenant environments, terminal servers, and container hosts. Once an attacker gains initial access via web application exploits or phishing, they can leverage this vulnerability to move laterally across the network or compromise Active Directory Domain Controllers. Furthermore, executing code at the kernel level allows attackers to bypass and disable Endpoint Detection and Response (EDR) agents, severely impacting business continuity and data integrity.
Official Vendor Advisories & References
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Frequently Asked SecOps Questions (CVE-2024-38193)
FAQQ1. How critical is CVE-2024-38193 and is it actively exploited in the wild?
CVE-2024-38193 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 28.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2024-38193?
Primary impacted vendors include microsoft across windows, windows_server. Scope summary: Windows 10, Windows 11, and Windows Server 2008, 2012, 2016, 2019, 2022 running unpatched afd.sys drivers prior to the August 2024 security updates
Q3. What temporary mitigations or workarounds exist for CVE-2024-38193 before patching?
[Mitigation] Immediately apply the Microsoft August 2024 security updates and monitor for unauthorized local account activities Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2024-38193
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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