CVE-2024-38239: Windows Kerberos Privilege Escalation Flaw

CVE-2024-38239 Overview

CVE-2024-38239 is an elevation of privilege vulnerability in the Windows Kerberos authentication component. Microsoft disclosed the flaw as part of its September 2024 security update cycle. An authenticated attacker with high privileges on the network can exploit the vulnerability to elevate privileges further, achieving impact to confidentiality, integrity, and availability.

The vulnerability affects a broad range of Windows client and server operating systems, including Windows Server 2008 through Windows Server 2022 23H2 and Windows 10 through Windows 11 24H2. The associated weakness is classified under [CWE-1390] (Weak Authentication).

Critical Impact
Successful exploitation allows an authenticated attacker to gain elevated privileges over Kerberos-authenticated resources, potentially compromising domain-joined systems across Windows client and server environments.

Affected Products

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

Discovery Timeline

2024-09-10 - CVE-2024-38239 published to NVD by Microsoft
2024-09-10 - Microsoft releases security patch as part of September 2024 Patch Tuesday
2026-08-10 - Last updated in NVD database

Technical Details for CVE-2024-38239

Vulnerability Analysis

CVE-2024-38239 is an elevation of privilege vulnerability in the Windows Kerberos implementation. Kerberos is the default authentication protocol for Active Directory domains and governs the issuance of tickets used to authenticate users and services. The flaw enables an authenticated attacker to escalate privileges by abusing weaknesses in how Kerberos validates or processes authentication material.

Microsoft's advisory identifies the network as the attack vector and requires the attacker to already hold high-privilege access. Successful exploitation yields high impact across confidentiality, integrity, and availability, indicating the ability to access protected resources, modify authentication state, or disrupt service on the target host.

The underlying weakness is categorized as [CWE-1390] (Weak Authentication), indicating the affected authentication logic accepts, produces, or validates credentials or tickets in a manner that does not sufficiently enforce identity guarantees.

Root Cause

Microsoft has not published detailed root cause information beyond mapping the flaw to weak authentication in the Kerberos subsystem. Because Kerberos handles ticket-granting tickets (TGTs), service tickets, and Privilege Attribute Certificate (PAC) validation, weaknesses in any of these code paths can result in privilege escalation across a Windows domain.

Attack Vector

The attack path requires the adversary to first authenticate with high privileges to a system participating in Kerberos authentication. From there, the attacker leverages the vulnerable code path to obtain privileges beyond those originally granted. No user interaction is required, and the attack complexity is low, making exploitation reliable once prerequisites are met.

No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS score is approximately 1.75% at the 75th percentile, indicating moderate exploitation likelihood relative to other tracked CVEs.

See the Microsoft Security Update CVE-2024-38239 advisory for vendor guidance.

Detection Methods for CVE-2024-38239

Indicators of Compromise

Unexpected Kerberos ticket-granting service (TGS) requests from accounts that do not typically request them.
Anomalous privilege changes on domain-joined hosts shortly after Kerberos authentication events.
Kerberos events with unusual encryption types or PAC validation failures logged in the Security event log.

Detection Strategies

Monitor Windows Security event IDs 4768, 4769, and 4770 for irregular ticket requests, renewals, or encryption downgrades.
Correlate authentication events on domain controllers with subsequent privileged actions on member servers within short time windows.
Alert on newly created or modified accounts that immediately obtain elevated Kerberos service tickets.

Monitoring Recommendations

Enable Kerberos authentication auditing across all domain controllers and forward logs to a central analytics platform.
Baseline normal Kerberos ticket volumes per account and flag statistical deviations.
Track privileged group membership changes and cross-reference with recent Kerberos authentication activity.

How to Mitigate CVE-2024-38239

Immediate Actions Required

Apply the September 2024 Microsoft security updates to all affected Windows client and server systems.
Prioritize patching of domain controllers and Tier 0 assets before member servers and workstations.
Rotate credentials for privileged accounts, including the krbtgt account, if compromise is suspected.

Patch Information

Microsoft released patches for CVE-2024-38239 through the Microsoft Security Response Center on 2024-09-10. Administrators should consult the Microsoft Security Update CVE-2024-38239 advisory to identify the specific KB update applicable to each affected Windows build and deploy it through Windows Update, WSUS, or the Microsoft Update Catalog.

Workarounds

No official workaround is documented by Microsoft; patching is the required remediation.
Restrict access to domain controllers and limit which accounts can authenticate interactively to Tier 0 systems.
Enforce the principle of least privilege and remove unnecessary membership from privileged groups such as Domain Admins and Enterprise Admins.

bash

# Verify the September 2024 security update is installed on Windows hosts
Get-HotFix | Where-Object { $_.InstalledOn -ge (Get-Date '2024-09-10') } | Sort-Object InstalledOn -Descending

# Query domain controllers for recent Kerberos authentication events
Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4769} -MaxEvents 100 |
    Select-Object TimeCreated, @{Name='Account';Expression={$_.Properties[0].Value}}, @{Name='Service';Expression={$_.Properties[2].Value}}