In early 2024, security researchers discovered CVE-2024-11859, a vulnerability tied to how certain applications in Windows search and load dynamic-link libraries (DLLs). This issue—commonly known as DLL Search Order Hijacking—can allow an attacker with existing administrator privileges to inject and execute arbitrary code on affected machines.

This article explains how the vulnerability works, provides a code snippet that demonstrates the concept, and connects you to original resources for a deeper understanding. The goal is to help IT administrators, security professionals, and curious minds quickly grasp the risk, impact, and exploitation.

What Is DLL Search Order Hijacking?

Windows applications often use DLLs: shared libraries loaded at runtime to provide various features. When a program calls for a DLL, Windows looks for it using a specific *search order*. If a malicious DLL with the right name is placed in a folder searched before the legitimate file, the application might load the attacker's code instead.

DLL Hijacking happens when attackers exploit this weakness, potentially taking control of the process and running arbitrary code in its context.

With CVE-2024-11859, the risk is that an attacker with admin access can plant a malicious DLL in a location that will be loaded by a privileged application—leading to escalation of control or persistence.

Vulnerability Details

- CVE: CVE-2024-11859

Type: DLL Search Order Hijacking

- Prerequisites: Local attacker must already have administrator-level access (e.g., obtained via phishing or previous exploit).
- Impact: Arbitrary code execution on the system, running with application-level or system-level privileges depending on the victim process.

Attacker knows a program loads a DLL by name but does not hard-code the DLL’s path.

3. Attacker plants a malicious DLL (with the same name) in a directory where Windows will check before the actual system directory.
4. Next time the app runs, the attacker’s DLL gets loaded instead of the real one, and the malicious code is executed.

Step-by-Step Example Exploit

Let’s say a legitimate application (VulnApp.exe) loads a DLL named MyHelper.dll but does not specify its full path. It just calls:

// Inside VulnApp.exe
LoadLibraryA("MyHelper.dll");

An attacker can write a fake MyHelper.dll. For demonstration, in C

// malicious MyHelper.c
#include <windows.h>
BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) {
    switch (ul_reason_for_call) {
        case DLL_PROCESS_ATTACH:
            MessageBoxA(NULL, "Hacked by DLL Hijack!", "CVE-2024-11859", MB_OK);
            // Attacker can execute any code here: launch reverse shell, add user, etc.
            break;
    }
    return TRUE;
}

Compile it

cl /LD MyHelper.c /Fe:MyHelper.dll

Result

The attacker’s code runs under the privileges of VulnApp.exe. If the program is running as SYSTEM, so is the attacker’s code.

Real-World Demonstration

Microsoft describes DLL search order problems in security bulletin:
https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-search-order

Detailed original CVE reports:
- NVD CVE-2024-11859 Entry
- Mitre CVE Record

Detection: Unless security software watches abnormal DLL activity, the attack is stealthy.

- Limitation: Exploit requires administrator access. This reduces initial threat, but enables lateral movements or persistence for attackers already in a compromised network.

Set the DLL search order safely: Developers can use SetDefaultDllDirectories API.

- Restrict write access: Only give administrative access to trusted users, and monitor changes in sensitive directories.

Final Thoughts

CVE-2024-11859 is a classic case of DLL Search Order Hijacking. While it doesn’t let outside attackers in on its own, it’s a powerful tool for anyone who has already broken into your system with admin rights. Immediate patching, code review, and cautious privilege granting are keys to defense.

Learn more

- CVE-2024-11859 official entry
- Microsoft DLL Security Guidance
- DLL Hijacking Explained by RedSiege

Timeline

Published on: 04/07/2025 09:15:15 UTC
Last modified on: 04/16/2025 11:15:41 UTC