CVE-2022-22942 Overview
CVE-2022-22942 is a Use-After-Free vulnerability in the vmwgfx driver that enables local privilege escalation on affected VMware Photon OS systems. The vulnerability allows unprivileged users to gain access to files opened by other processes on the system through a dangling 'file' pointer, potentially leading to complete system compromise.
Critical Impact
Local attackers with low-privilege access can exploit this vulnerability to escalate privileges and gain unauthorized access to sensitive files opened by other processes, potentially achieving root-level access on vulnerable systems.
Affected Products
- VMware Photon OS 3.0
- VMware Photon OS 4.0
- Linux systems running the vmwgfx graphics driver
Discovery Timeline
- 2022-01-27 - Vulnerability disclosed on OpenWall OSS Security mailing list
- 2023-12-13 - CVE CVE-2022-22942 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2022-22942
Vulnerability Analysis
This Use-After-Free vulnerability resides in the vmwgfx driver, which is the Direct Rendering Manager (DRM) driver for VMware virtual GPUs. The core issue involves improper handling of file pointers within the driver, resulting in a dangling pointer condition that persists after the associated memory has been freed.
When the vulnerability is triggered, an unprivileged local user can exploit the dangling file pointer to access files that have been opened by other processes running on the system. This cross-process file access bypasses normal access control mechanisms, allowing attackers to read sensitive data or potentially manipulate system resources they should not have access to.
The attack requires local access to the system, making it particularly relevant in multi-tenant environments, shared computing infrastructure, and containerized deployments where privilege separation is critical for security isolation.
Root Cause
The vulnerability stems from a Use-After-Free condition (CWE-416) in the vmwgfx driver's file handling logic. When certain operations are performed, the driver fails to properly invalidate or nullify file pointers after the underlying file object has been released. This leaves a dangling pointer that can be dereferenced, allowing access to memory that has been reallocated for other purposes—including file descriptors belonging to other processes.
The improper memory management creates a window of opportunity where the stale pointer remains accessible, enabling attackers to craft operations that leverage this pointer to gain unauthorized file access.
Attack Vector
The attack is executed locally by an authenticated user with low-level privileges. The attacker interacts with the vmwgfx driver through its exposed interfaces to trigger the Use-After-Free condition. By carefully timing operations and manipulating the state of file pointers, the attacker can:
- Trigger the freeing of a file object while retaining access to its pointer
- Wait for or force reallocation of the memory region
- Access the dangling pointer to read or interact with files owned by other processes
- Leverage the cross-process file access to escalate privileges or exfiltrate sensitive data
The vulnerability does not require user interaction and can be exploited without any special privileges beyond basic local access to the system.
Detection Methods for CVE-2022-22942
Indicators of Compromise
- Unusual ioctl calls to /dev/dri/ device nodes from low-privilege processes
- Unexpected file descriptor operations involving the vmwgfx driver
- Processes accessing files outside their expected scope or permission level
- Memory access patterns indicating Use-After-Free exploitation attempts
Detection Strategies
- Monitor system calls related to DRM/DRI device interactions using auditd or similar tools
- Implement kernel-level monitoring for anomalous vmwgfx driver behavior
- Deploy endpoint detection solutions capable of identifying privilege escalation attempts
- Use SentinelOne's behavioral AI to detect exploitation patterns characteristic of Use-After-Free attacks
Monitoring Recommendations
- Enable audit logging for device node access in /dev/dri/ directory
- Configure alerts for unexpected privilege changes following vmwgfx driver interactions
- Monitor for processes attempting to access file descriptors across process boundaries
- Review kernel logs for vmwgfx-related errors or warnings that may indicate exploitation attempts
How to Mitigate CVE-2022-22942
Immediate Actions Required
- Apply the latest security updates for VMware Photon OS immediately
- Review system access logs to identify any potential exploitation attempts
- Restrict local user access to systems running vulnerable vmwgfx driver versions
- Consider disabling the vmwgfx driver if VMware virtual GPU functionality is not required
Patch Information
VMware has released security updates addressing this vulnerability for affected Photon OS versions. Administrators should apply the patches documented in the following security advisories:
Ensure that the kernel and associated driver packages are updated to the patched versions specified in these advisories.
Workarounds
- Restrict access to DRI device nodes (/dev/dri/*) to trusted users only
- Implement strict user access controls to limit local authentication on vulnerable systems
- Use container isolation or virtualization to limit the impact of potential exploitation
- Monitor and audit vmwgfx driver usage until patches can be applied
# Configuration example - Restrict access to DRI devices
# Add to /etc/udev/rules.d/99-dri-restrict.rules
KERNEL=="card*", SUBSYSTEM=="drm", MODE="0660", GROUP="video"
# Ensure only trusted users are in the video group
# Check current members
getent group video
# Reload udev rules
udevadm control --reload-rules && udevadm trigger
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
