CVE DatabaseCVE-2019-1214

Updated 2026-06-17한국어 권고문 →

CVE-2019-12147.8/HIGHCISA KEVCWE-119

Windows CLFS (Common Log File System) Driver Elevation of Privilege Vulnerability (CVE-2019-1214) Technical Analysis and Mitigation Guide

⚡ Jump to Patch

Affected Vendors

microsoft

Affected Components

windows, windows_server

Published Date

2019-09-11

CVSS v3.1

7.8

HIGH

EPSS (30d)

1.4%

FIRST.org

CISA KEV

Exploited

NVD Source ↗

Executive & SecOps Summary

SECOPS ASSESSMENT

Affected Scope

Microsoft Windows operating systems including Windows 7, 8.1, 10, and Windows Server 2008, 2012, 2016, 2019 utilizing the CLFS driver

Impact

Local attackers can trigger kernel memory corruption to execute arbitrary code with SYSTEM privileges, leading to complete system takeover

Mitigation

Apply the official Microsoft security patches immediately and monitor for unauthorized local access and anomalous CLFS log file creation

Affected Products & Version Scope

All supported and legacy versions of Windows and Windows Server operating systems utilizing the CLFS driver

Remediation & Live Workaround Commands

PATCH & WORKAROUND

1. Official Patch & Version Upgrade Commands

Apply the latest cumulative security updates provided by Microsoft. You can force-install the required updates using the PowerShell Windows Update module as shown below:

powershell

# Install and import the PSWindowsUpdate module to apply pending security patches
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck
Get-WindowsUpdate -Category 'Security Updates' -AcceptAll -Install -AutoReboot

2. Temporary Workaround & Hardening Configuration

If immediate patching is not feasible, restrict local access to non-essential users and monitor writable directories (such as C:\Users\Public\ or C:\Temp\) for unauthorized creation of .blf and .regtrans-ms files. You can use PowerShell to audit and restrict write permissions on sensitive directories.

powershell

# Example: Restrict write permissions on a specific shared directory to prevent malicious BLF placement
$Path = 'C:\SharedData'
$Acl = Get-Acl $Path
$Ar = New-Object System.Security.AccessControl.FileSystemAccessRule('Everyone', 'Write', 'Deny')
$Acl.AddAccessRule($Ar)
Set-Acl $Path $Acl

3. Log Audit & IoC Verification Commands

Verify the current version of the clfs.sys driver and inspect the Windows Event Logs for any system crashes or anomalies related to the Common Log File System.

powershell

# Check the file version of the CLFS driver
$clfsPath = 'C:\Windows\System32\drivers\clfs.sys'
if (Test-Path $clfsPath) {
    $version = (Get-Item $clfsPath).VersionInfo.FileVersion
    Write-Output "CLFS Driver Version: $version"
    
    # Query Event Viewer for system errors or bugchecks related to CLFS
    Get-WinEvent -FilterHashtable @{LogName='System'; ProviderName='Microsoft-Windows-WER-SystemErrorReporting'} -ErrorAction SilentlyContinue | 
        Where-Object {$_.Message -like '*clfs.sys*' -or $_.Message -like '*0x00000050*'} | 
        Select-Object TimeCreated, Id, Message | Format-List
} else {
    Write-Warning 'CLFS driver file not found in the standard path.'
}

Interactive SecOps Remediation Checklist

0/4 (0%)

Recommended Security Control & Mitigation Partner

SentinelOne Singularity AI EDR

This vulnerability is actively exploited in the wild; immediately apply the latest Microsoft cumulative security updates to mitigate the risk.

Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot

Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.

100% MITRE ATT&CK Detection · 1-Click Rollback

See Autonomous Endpoint Protection in Action

Technical Root Cause & Exploitation Mechanics

1. Vulnerability Overview & Root Cause

This vulnerability is a memory corruption issue (CWE-119) within the Windows Common Log File System (CLFS) driver (clfs.sys). CLFS is a general-purpose logging subsystem used by both kernel-mode and user-mode applications. The root cause lies in the driver's improper handling of objects in memory when parsing CLFS log files (.blf). When a user-mode application passes a specially crafted log file metadata structure to the kernel via API calls, the driver fails to validate the boundaries and integrity of the input, leading to an out-of-bounds write or use-after-free condition in the kernel pool.

2. Exploitation Mechanics & Attack Scenario

To exploit this vulnerability, an attacker must first gain local execution access on the target system with low-privilege user rights. The attacker then constructs a malicious Base Log File (.blf) containing corrupted metadata structures. By invoking CLFS-related APIs such as CreateLogFile, the attacker forces the kernel driver to parse the malformed file. This triggers memory corruption within the kernel pool, allowing the attacker to overwrite critical kernel structures, hijack the execution flow, and execute arbitrary shellcode with elevated NT AUTHORITY\SYSTEM privileges.

3. Infrastructure & Business Impact

As a vulnerability listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, CVE-2019-1214 poses a severe threat. Local Privilege Escalation (LPE) vulnerabilities are critical components of multi-stage cyber attacks. Threat actors leverage LPE to bypass endpoint security controls, perform lateral movement, dump credentials, and deploy ransomware across the enterprise network. Successful exploitation on critical assets like Domain Controllers or database servers can result in complete infrastructure compromise.

Official Vendor Advisories & References

NVD Original English Description

An elevation of privilege vulnerability exists when the Windows Common Log File System (CLFS) driver improperly handles objects in memory, aka 'Windows Common Log File System Driver Elevation of Privilege Vulnerability'.

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1214

Source: secure@microsoft.com · Patch, Vendor Advisory

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1214

Source: af854a3a-2127-422b-91ae-364da2661108 · Patch, Vendor Advisory

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1214

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0 · US Government Resource

Frequently Asked SecOps Questions (CVE-2019-1214)

FAQ

Q1. How critical is CVE-2019-1214 and is it actively exploited in the wild?

CVE-2019-1214 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 1.4%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.

Q2. Which vendors and products are affected by CVE-2019-1214?

Primary impacted vendors include microsoft across windows, windows_server. Scope summary: All supported and legacy versions of Windows and Windows Server operating systems utilizing the CLFS driver

Q3. What temporary mitigations or workarounds exist for CVE-2019-1214 before patching?

[Mitigation] Apply the official Microsoft security patches immediately and monitor for unauthorized local access and anomalous CLFS log file creation Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.

SECOPS WORKBENCH INTEGRATION