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Microsoft Windows Server 2016 - Win32k Elevation of Privilege

High
Exploitwindowslocalexploitwindows
Published: Sun May 25 2025 (05/25/2025, 00:00:00 UTC)
Source: Exploit-DB RSS Feed

Description

Microsoft Windows Server 2016 - Win32k Elevation of Privilege

AI-Powered Analysis

AILast updated: 06/11/2025, 21:14:42 UTC

Technical Analysis

This security threat concerns a local privilege escalation vulnerability in Microsoft Windows Server 2016, specifically targeting the Win32k subsystem, identified as CVE-2023-29336. The vulnerability allows an attacker with local access to elevate privileges from a lower-privileged user to SYSTEM level by exploiting weaknesses in the handling of window menus and kernel objects within the Win32k driver. The provided exploit code, written in C, manipulates internal kernel structures related to menus and window classes to perform token stealing, a common technique to gain SYSTEM privileges. It achieves this by creating and manipulating fake menu objects and window classes, leveraging offsets within the EPROCESS structure to locate and replace the current process token with that of the SYSTEM process (PID 4). The exploit uses direct memory reads and writes to kernel memory via crafted window handles and menu objects, bypassing normal security checks. The code dynamically resolves necessary kernel functions from win32u.dll, registers multiple window classes, creates numerous windows and menus, and performs complex memory manipulations to achieve the elevation of privilege. The exploit culminates in spawning a hidden command shell with SYSTEM privileges, demonstrating full control over the compromised system. No patch links are provided, and no known exploits in the wild have been reported yet, but the availability of functional exploit code increases the risk of imminent exploitation. The vulnerability does not require user interaction beyond local code execution and does not require authentication beyond local access, making it a potent threat for attackers who have already gained limited access to a system.

Potential Impact

For European organizations, this vulnerability poses a significant risk to the confidentiality, integrity, and availability of critical Windows Server 2016 systems. Since Windows Server 2016 remains widely deployed in enterprise environments across Europe for domain controllers, file servers, and application hosting, successful exploitation could allow attackers to gain SYSTEM-level privileges, effectively full control over affected servers. This could lead to unauthorized access to sensitive data, disruption of business-critical services, lateral movement within networks, and deployment of ransomware or other malicious payloads. The local nature of the exploit means attackers must first gain some form of access (e.g., via phishing, compromised credentials, or other vulnerabilities), but once inside, this exploit can be used to escalate privileges and bypass security controls. The lack of patches or mitigations at the time of publication increases the urgency for European organizations to implement defensive measures. The exploit's complexity and reliance on kernel memory manipulation also suggest that detection may be challenging without specialized monitoring. Given the strategic importance of Windows Server infrastructure in sectors such as finance, government, healthcare, and critical infrastructure in Europe, exploitation could have severe operational and reputational consequences.

Mitigation Recommendations

1. Immediate mitigation should include restricting local access to Windows Server 2016 systems, limiting administrative privileges, and enforcing strict access controls to reduce the risk of initial foothold. 2. Deploy host-based intrusion detection systems (HIDS) and endpoint detection and response (EDR) solutions capable of monitoring unusual kernel-level activity, such as abnormal window class registrations or menu manipulations. 3. Monitor for suspicious process creations, especially hidden command shells spawned from system processes, as the exploit culminates in such behavior. 4. Employ application whitelisting and restrict execution of unauthorized binaries and scripts to prevent execution of exploit code. 5. Network segmentation should be enforced to limit lateral movement from compromised hosts. 6. Regularly audit and harden Windows Server configurations, including disabling unnecessary services and features that could be leveraged for local access. 7. Since no official patch is available, consider deploying third-party kernel integrity monitoring tools or applying unofficial mitigations such as disabling or restricting access to vulnerable Win32k components where feasible. 8. Prepare incident response plans specifically addressing privilege escalation scenarios and conduct threat hunting exercises focused on Win32k exploitation indicators. 9. Keep abreast of Microsoft advisories for forthcoming patches and apply them promptly once released.

Affected Countries

United KingdomUnited Kingdom
GermanyGermany
FranceFrance
NetherlandsNetherlands
ItalyItaly
SpainSpain
PolandPoland
SwedenSweden
BelgiumBelgium
IrelandIreland
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Technical Details

Edb Id
52301
Has Exploit Code
true
Code Language
c

Indicators of Compromise

Exploit Source Code

Exploit Code

Exploit code for Microsoft Windows Server 2016 - Win32k Elevation of Privilege

# Exploit Title: Microsoft Windows Server 2016 - Win32k Elevation of
Privilege
# Date: 2025-05-19
# Exploit Author: Milad Karimi (Ex3ptionaL)
# Contact: miladgrayhat@gmail.com
# Zone-H: www.zone-h.org/archive/notifier=Ex3ptionaL
# Country: United Kingdom
# CVE : CVE-2023-29336




#include <windows.h>
#include <stdio.h>
#include <tchar.h>

#define IDM_MYMENU 101
#define IDM_EXIT 102
#define IDM_DISABLE 0xf120
#define IDM_ENABLE 104
#define EPROCESS_UNIQUE_PROCESS_ID_OFFSET 0x440
#define EPROCESS
... (14559 more characters)
Code Length: 15,059 characters • Language: C/C++

Threat ID: 68489db97e6d765d51d530f1

Added to database: 6/10/2025, 9:03:53 PM

Last enriched: 6/11/2025, 9:14:42 PM

Last updated: 8/1/2025, 7:20:55 AM

Views: 12

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