Windows Error Reporting (WER) Hard Link Elevation of Privilege Vulnerability (CVE-2019-1315)
Executive & SecOps Summary
SECOPS ASSESSMENTWindows 7, 8.1, 10, and Windows Server 2008, 2012, 2016, 2019 with Windows Error Reporting (WER) enabled
A local attacker can exploit hard links to overwrite or manipulate arbitrary system files, leading to arbitrary code execution with SYSTEM privileges
Immediately apply the official Microsoft security patches and restrict local write permissions on temporary directories prior to patching
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the latest cumulative security updates provided by Microsoft. You can force the installation of pending security updates using PowerShell.
# Install PSWindowsUpdate module and apply all security patches
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict write permissions on the WER directories to prevent low-privileged users from creating malicious hard links.
# Restrict write permissions for standard 'Users' on the WER directory
$Path = 'C:\ProgramData\Microsoft\Windows\WER'
$Acl = Get-Acl $Path
$Ar = New-Object System.Security.AccessControl.FileSystemAccessRule('Users', 'Write', 'ContainerInherit,ObjectInherit', 'None', 'Deny')
$Acl.AddAccessRule($Ar)
Set-Acl $Path $Acl3. Log Audit & IoC Verification Commands
Audit the Windows Event Logs for anomalous Windows Error Reporting events or unexpected file modifications in the WER directories.
# Query Windows Event Logs for WER warning and error events
Get-WinEvent -FilterHashtable @{
LogName='Application'
ProviderName='Windows Error Reporting'
Level=1,2,3
} -MaxEvents 50 | Select-Object TimeCreated, Id, Message | Format-Table -WrapBlock 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.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
An elevation of privilege vulnerability exists in the Windows Error Reporting (WER) manager due to improper handling of hard links (CWE-59). The WER service runs with elevated SYSTEM privileges to collect diagnostic data and generate error reports. When performing file operations within directories accessible by low-privileged users, the service fails to properly validate whether a file path is a direct file or a hard link pointing to a critical system resource, allowing unauthorized file manipulation.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first gain local execution access on the target system. The attacker monitors the directory where the WER service creates temporary files (e.g., C:\ProgramData\Microsoft\Windows\WER\Temp). By creating a hard link with the same name as the expected temporary file pointing to a target system file (such as a system DLL or service executable), the attacker tricks the high-privileged WER service into writing data to or modifying the permissions of the target system file. This allows the attacker to overwrite critical system files and execute arbitrary code with SYSTEM privileges.
3. Infrastructure & Business Impact
This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. While a local elevation of privilege (EoP) vulnerability cannot be used for initial external access, it is a critical component in multi-stage attacks. Once attackers gain a foothold via phishing or web application exploits, they leverage EoP vulnerabilities to bypass security controls, establish persistence, disable endpoint protection, and perform lateral movement across the enterprise network.
Official Vendor Advisories & References
An elevation of privilege vulnerability exists when Windows Error Reporting manager improperly handles hard links, aka 'Windows Error Reporting Manager Elevation of Privilege Vulnerability'. This CVE ID is unique from CVE-2019-1339, CVE-2019-1342.
Frequently Asked SecOps Questions (CVE-2019-1315)
FAQQ1. How critical is CVE-2019-1315 and is it actively exploited in the wild?
CVE-2019-1315 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 3.5%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2019-1315?
Primary impacted vendors include microsoft across windows, windows_error_reporting. Scope summary: All supported and some end-of-life versions of Windows operating systems, including Windows 7, 8.1, 10, and Windows Server 2008, 2012, 2016, 2019
Q3. What temporary mitigations or workarounds exist for CVE-2019-1315 before patching?
[Mitigation] Immediately apply the official Microsoft security patches and restrict local write permissions on temporary directories prior to patching Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2019-1315
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