CVE-2024-6769: Windows DLL Hijacking Privilege Escalation

CVE-2024-6769 Overview

CVE-2024-6769 is a DLL Hijacking vulnerability caused by drive remapping combined with poisoning of the activation cache in Microsoft Windows. This vulnerability affects Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, and Windows Server 2022. A malicious authenticated attacker can exploit this flaw to elevate from a medium integrity process to a high integrity process without triggering a User Account Control (UAC) prompt.

Critical Impact

This vulnerability enables authenticated attackers to bypass UAC protections and achieve privilege escalation from medium to high integrity, potentially leading to full system compromise without user interaction.

Affected Products

• Microsoft Windows 10
• Microsoft Windows 11
• Microsoft Windows Server 2016
• Microsoft Windows Server 2019
• Microsoft Windows Server 2022

Discovery Timeline

• 2024-09-26 - CVE-2024-6769 published to NVD
• 2025-08-29 - Last updated in NVD database

Technical Details for CVE-2024-6769

Vulnerability Analysis

This vulnerability (CWE-426: Untrusted Search Path) exploits a weakness in how Windows handles DLL loading in conjunction with drive remapping capabilities. The attack chain combines two techniques: first, the attacker manipulates drive mappings to redirect file system paths, and second, they poison the Windows activation cache to force legitimate high-integrity processes to load malicious DLLs from attacker-controlled locations.

The fundamental issue lies in the trust relationship between Windows components and the file system. When a high-integrity process attempts to load a DLL, it follows a search path that can be influenced by drive remapping operations. By carefully poisoning the activation cache, an attacker can inject entries that redirect DLL lookups to malicious payloads.

Root Cause

The root cause is an untrusted search path vulnerability where Windows fails to properly validate the integrity and authenticity of DLL paths when drive mappings have been modified. The activation cache, which is designed to accelerate COM object activation, can be poisoned to contain references to attacker-controlled DLLs. This occurs because the cache validation does not account for scenarios where drive letters have been remapped to point to different physical or logical locations.

Attack Vector

The attack requires local access and an authenticated user with at least medium integrity privileges. The attacker performs the following operations:

1. Creates a malicious DLL payload designed to execute arbitrary code at high integrity
2. Remaps a drive letter to point to an attacker-controlled directory containing the malicious DLL
3. Poisons the Windows activation cache to reference the remapped path
4. Triggers a high-integrity process to load the cached COM object, which now resolves to the malicious DLL
5. The DLL executes with high integrity privileges, bypassing UAC entirely

The vulnerability is particularly dangerous because it does not require any user interaction once the initial authenticated access is obtained. Technical details and proof-of-concept code are available in the Fortra Security Advisory and GitHub repository.

Detection Methods for CVE-2024-6769

Indicators of Compromise

• Unexpected drive remapping events or changes to symbolic links pointing to system directories
• Modifications to the Windows activation cache located in user profile directories
• DLL loading from non-standard or user-writable paths by high-integrity system processes
• Process creation events showing privilege escalation without corresponding UAC prompts

Detection Strategies

• Monitor for SUBST command usage or API calls that create drive mappings (DeviceIoControl with IOCTL_MOUNTMGR_CREATE_POINT)
• Audit access to and modifications of the activation cache files under %LOCALAPPDATA%\Microsoft\Windows\Caches\
• Implement DLL load monitoring for high-integrity processes loading from unexpected paths
• Deploy behavioral analytics to detect sequences of drive remapping followed by high-privilege process spawning

Monitoring Recommendations

• Enable Windows Security Event logging for process creation (Event ID 4688) with command line auditing
• Configure Sysmon to capture DLL load events (Event ID 7) and file system changes for cache directories
• Establish baselines for normal drive mapping activity and alert on anomalous patterns
• Monitor for processes transitioning from medium to high integrity without corresponding UAC events

How to Mitigate CVE-2024-6769

Immediate Actions Required

• Restrict drive remapping capabilities for standard users through Group Policy where operationally feasible
• Implement application control policies to prevent DLL loading from user-writable directories
• Deploy endpoint detection and response (EDR) solutions configured to detect UAC bypass techniques
• Audit systems for signs of compromise using the indicators listed above

Patch Information

Microsoft has not classified this as a vulnerability requiring a security update, considering UAC bypass as a defense-in-depth bypass rather than a security boundary violation. Organizations should implement compensating controls and monitor for exploitation. For detailed technical information, refer to the Fortra Security Advisory FR-2024-002.

Workarounds

• Configure UAC to "Always Notify" mode to maximize protection against bypass attempts
• Implement Windows Defender Application Control (WDAC) or AppLocker policies to restrict DLL loading
• Remove local administrator privileges from standard users where possible to limit exploitation impact
• Enable Credential Guard and other virtualization-based security features to protect high-integrity processes