CVE-2024-49046: Windows 10 1507 Privilege Escalation Flaw

CVE-2024-49046 Overview

CVE-2024-49046 is an elevation of privilege vulnerability in the Windows Win32 Kernel Subsystem. The flaw stems from a time-of-check time-of-use (TOCTOU) race condition [CWE-367] that a local, authenticated attacker can exploit to gain SYSTEM-level privileges. Microsoft published the advisory as part of its November 2024 Patch Tuesday release and the vulnerability affects a wide range of supported Windows client and server versions.

Critical Impact

Successful exploitation grants SYSTEM-level code execution from a low-privileged local account, enabling full host compromise, credential theft, and persistence across most supported Windows builds.

Affected Products

• Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2) and Windows 11 (22H2, 23H2, 24H2)
• Microsoft Windows Server 2008, 2008 R2, 2012, 2012 R2, 2016, 2019
• Microsoft Windows Server 2022, 2022 23H2, and Windows Server 2025

Discovery Timeline

• 2024-11-12 - CVE-2024-49046 published to NVD and Microsoft releases security update
• 2024-11-18 - Last updated in NVD database

Technical Details for CVE-2024-49046

Vulnerability Analysis

The vulnerability resides in the Win32 kernel subsystem, the component that brokers user-mode requests into kernel-mode graphics and windowing services. An attacker authenticated to the target system can trigger the race condition through crafted system calls. Successful exploitation yields full read, write, and execute control over the host with kernel privileges.

The vulnerability is exploitable only from a local context and requires no user interaction. Because the Win32 kernel subsystem runs in ring 0, code that wins the race executes with SYSTEM authority. This makes the flaw a strong second-stage primitive after initial access, malware execution, or browser exploitation.

Root Cause

The root cause is a time-of-check time-of-use (TOCTOU) flaw [CWE-367]. The kernel validates an attacker-controlled object or pointer at one point in execution, then dereferences or operates on it later without re-validation. A concurrent thread can swap the underlying object between the check and the use, causing the kernel to act on attacker-influenced data.

Attack Vector

Exploitation requires local code execution as a standard user. The attacker spawns at least two threads: one issues the targeted Win32k system call, and a second races to mutate the referenced kernel object between validation and use. Winning the race corrupts kernel state in a way that leads to arbitrary kernel read, write, or function pointer hijack and ultimately SYSTEM privileges.

No public proof-of-concept exploit code is referenced in the advisory. Refer to the Microsoft CVE-2024-49046 Advisory for additional vendor guidance.

Detection Methods for CVE-2024-49046

Indicators of Compromise

• Unexpected child processes spawned by standard user sessions running with NT AUTHORITY\SYSTEM integrity
• Crash dumps or BugCheck events referencing win32k.sys, win32kfull.sys, or win32kbase.sys originating from non-administrative user contexts
• Token manipulation events where a low-privileged process suddenly acquires SeDebugPrivilege or a SYSTEM token

Detection Strategies

• Hunt for processes that change integrity level from Medium to System without going through a legitimate elevation path such as consent.exe or a signed service
• Correlate Sysmon Event ID 10 (process access) and Event ID 1 (process create) for handle requests against lsass.exe immediately following short-lived multi-threaded user processes
• Apply behavioral detection for kernel exploitation patterns: rapid repeated NT system calls from a single process combined with thread spraying on Win32k entry points

Monitoring Recommendations

• Enable Windows Defender Application Control or AppLocker auditing to surface unsigned binaries executing from user-writable paths prior to privilege escalation
• Forward kernel and security event logs to a centralized data lake and retain process lineage to reconstruct the full exploit chain after the fact
• Monitor for new scheduled tasks, services, and driver loads created within minutes of a suspicious local logon

How to Mitigate CVE-2024-49046

Immediate Actions Required

• Apply the November 2024 Microsoft security updates to every affected Windows client and server build without delay
• Inventory legacy systems such as Windows Server 2008 and 2012 R2 and confirm Extended Security Update (ESU) coverage before deploying the patch
• Restrict local logon rights and remove unnecessary interactive users from servers and high-value workstations to reduce the local attacker surface

Patch Information

Microsoft released fixes for CVE-2024-49046 in the November 12, 2024 Patch Tuesday cycle. Administrators should consult the Microsoft CVE-2024-49046 Advisory for the specific KB article that corresponds to each affected Windows build and deploy through Windows Update, WSUS, or Microsoft Update Catalog.

Workarounds

• No official workaround is published by Microsoft; patching is the supported remediation path
• Enforce the principle of least privilege so that compromise of a low-privileged account does not provide an attacker with the local execution required to trigger the race
• Enable hypervisor-protected code integrity (HVCI) and Credential Guard where supported to raise the cost of post-exploitation kernel tampering

# Verify the November 2024 cumulative update is installed on Windows
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 10

# Audit local users with interactive logon rights
whoami /priv
net localgroup Users