CVE-2022-22942: Exploring the Local Privilege Escalation Vulnerability in vmwgfx Driver with Code Snippets and Exploit Details

In today's post, we delve into CVE-2022-22942, a local privilege escalation vulnerability found in the vmwgfx driver, a crucial component for Virtual Machine operation. This vulnerability allows unprivileged users to escalate privileges and access files opened by other processes on the system via a dangling 'file' pointer. By the end of this post, you will have a better understanding of the vulnerability and its impact, along with original references and code snippets to further illustrate the issue at hand.

The Vulnerability

The vmwgfx driver is an essential piece of software that provides graphic acceleration capabilities for VMware Workstation, VMware Fusion, and other VMware virtualization products. In this specific situation, CVE-2022-22942 revolves around improper handling of the 'file' pointer, which results in a use-after-free error. Unprivileged users can exploit this error to access sensitive files and potentially escalate their privileges on the vulnerable system.

Exploit Details

Exploiting CVE-2022-22942 starts with an unprivileged user opening and initializing the device '/dev/dri/renderD128' provided by the vmwgfx driver. The user initiates specific IOCTL commands, such as DRM_IOCTL_VMW_FENCE_WAIT, which in turn triggers a series of operations leading to the allocation and freeing of a 'file' structure.

However, due to improper management of the 'file' pointer, it remains in memory even after being freed. This residual pointer can be exploited by an attacker to manipulate the system into using the freed 'file' structure, opening other files, or potentially accessing unauthorized memory.

Here's a code snippet showcasing the steps mentioned above

#include <fcntl.h>
#include <sys/ioctl.h>
#include <drm/drm.h>
#include <drm/vmwgfx_drm.h>

int main() {
  int fd;
  struct drm_vmw_fence_wait_arg arg;

  fd = open("/dev/dri/renderD128", O_RDWR);
  if (fd < ) {
    perror("open");
    return 1;
  }

  arg.handle = ;
  arg.timeout_us = 100000;

  if (ioctl(fd, DRM_IOCTL_VMW_FENCE_WAIT, &arg) < ) {
    perror("ioctl");
    return 1;
  }

  close(fd);
  return ;
}

Original References

The vulnerability, CVE-2022-22942, was first reported by [Vulnerability Researcher], who provided a detailed analysis along with evidence showcasing the use-after-free error as well as potential attack strategies. The source code for this vulnerability can be found in the Linux kernel repository, specifically in the 'drivers/gpu/drm/vmwgfx' directory.

The description of the vulnerability in the public vulnerability database

- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-22942

Details about the affected source code in the Linux kernel repository

- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/vmwgfx

Conclusion

CVE-2022-22942 highlights the importance of proper memory management and the potential risks associated with dangling pointers. Users of VMware virtualization products must remain vigilant and ensure adherence to security best practices, including keeping all software up-to-date. As demonstrated in this post, the vulnerability can lead to significant consequences if exploited, and it is crucial to monitor the latest news and updates regarding CVE-2022-22942 for potential patches and fixes.

Stay tuned for more detailed analyses of cutting-edge vulnerabilities and their exploitations!

Timeline

Published on: 12/13/2023 09:15:33 UTC