CVE-2018-8405

What is the DirectX Graphics Kernel?

The DirectX Graphics Kernel driver (dxgkrnl.sys) is the kernel-mode component underpinning Windows' graphics stack, mediating access between user-mode graphics applications/drivers and the GPU. Because it runs in the kernel and processes requests originating from user-mode code — including from low-privileged, sandboxed, or even guest-session processes — bugs here are a recurring source of Windows local privilege escalation vulnerabilities.

Overview

CVE-2018-8405 is an elevation of privilege vulnerability caused by DXGKRNL's improper handling of objects in memory. A locally authenticated attacker who runs a specially crafted application can trigger the flaw to execute code in kernel mode, escalating from a low-privileged account to full SYSTEM control.

Technical Details

The vulnerability is classified under CWE-404 (Improper Resource Shutdown or Release), consistent with a use-after-free-style condition: DXGKRNL fails to properly manage the lifecycle of a kernel object, and a stale reference can later be manipulated by a user-mode caller to corrupt kernel memory. Because the attack vector is local with low attack complexity and only low privileges required, this bug type is typically used as a second-stage escalation primitive following an initial code-execution foothold from a browser, document, or other application-layer exploit.

Discovery

The issue was addressed through Microsoft's regular security update process as part of the August 2018 Patch Tuesday release.

Exploitation Context

CISA added CVE-2018-8405 to the KEV catalog in March 2022, and the entry notes confirmed use in ransomware operations — kernel privilege-escalation bugs like this one are commonly chained by ransomware affiliates and other intruders to move from an initial low-privileged foothold to full administrative control needed for mass encryption or credential harvesting.

Remediation

1. Apply the August 2018 Windows security update (or later cumulative update) addressing CVE-2018-8405.
2. Prioritize patching on endpoints where users regularly run untrusted or third-party code, given the local-only attack vector.
3. Apply least-privilege principles so that a compromised low-privileged account has fewer opportunities to reach vulnerable kernel-mode drivers.
4. Maintain EDR coverage tuned to detect anomalous privilege escalation attempts and unexpected SYSTEM-level process activity.
5. Ensure GPU/graphics drivers and the underlying OS are kept on a current, fully patched build as part of routine endpoint hardening.