CVE-2019-1214
Microsoft Windows Privilege Common Log File System (CLFS) Escalation Vulnerability
Description
CVE-2019-1214 is a high-severity privilege escalation vulnerability in the Microsoft Windows Common Log File System (CLFS) driver. The vulnerability exists because the CLFS driver improperly handles objects in memory, allowing a locally authenticated attacker to escalate privileges and gain full control over the affected system. CISA has added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. With an EPSS score of 3.68% (87.8th percentile), CVE-2019-1214 affects a wide range of Windows operating systems from Windows 7 through Windows 10 and all corresponding Server versions.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 10 1507 | - |
| microsoft | windows 10 1607 | - |
| microsoft | windows 10 1703 | - |
| microsoft | windows 10 1709 | - |
| microsoft | windows 10 1803 | - |
| microsoft | windows 10 1809 | - |
| microsoft | windows 10 1903 | - |
| microsoft | windows 7 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 1803 | - |
| microsoft | windows server 1903 | - |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows server 2016 | - |
| microsoft | windows server 2019 | - |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1214(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1214(US Government Resource)
Weakness Type
CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer is a vulnerability class where software performs operations on a memory buffer without properly verifying that the read or write operations stay within the allocated boundaries. In the context of CVE-2019-1214, the Windows CLFS driver fails to properly handle objects in memory, leading to a buffer boundary violation that can be exploited for privilege escalation from a low-privileged user account to SYSTEM level access.
Learn more: CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer
Impact Analysis
CVE-2019-1214 carries a CVSS 3.1 score of 7.8 (HIGH), indicating a significant privilege escalation threat across a broad range of Windows operating systems. The vulnerability requires local access with low-level privileges but no user interaction, making it well-suited for post-exploitation scenarios where an attacker has gained initial foothold through other means. Confidentiality (High): An attacker who escalates to SYSTEM level gains unrestricted access to all data on the system, including credentials, security tokens, and sensitive files. Integrity (High): SYSTEM-level access allows modification of system files, security policies, audit logs, and running processes. Availability (High): Full system compromise can lead to persistent malware deployment, denial of service, or complete system destruction. The breadth of affected products spanning Windows 7, Windows 8.1, Windows 10 (multiple versions), and all corresponding Windows Server editions significantly amplifies the organizational risk.
Exploit Maturity
CVE-2019-1214 is confirmed as actively exploited through its listing in the CISA Known Exploited Vulnerabilities catalog, with a remediation deadline of 2022-05-03. The EPSS score of 3.68% (87.8th percentile) indicates a notable probability of exploitation, though lower than some other actively exploited vulnerabilities. No public exploit code was identified in the NVD references for this specific CVE, but the active exploitation status confirmed by CISA indicates that working exploits exist in the wild and are being used by threat actors targeting the Windows CLFS driver. The CLFS subsystem has been a recurring target for exploitation, with multiple privilege escalation vulnerabilities discovered in this component over the years.
Remediation
- Apply vendor patches immediately as mandated by CISA KEV: Apply updates per vendor instructions. Microsoft has released security updates for all affected Windows versions in the September 2019 Patch Tuesday release.
- Verify that all affected Windows systems have been updated: Windows 10 (versions 1507, 1607, 1703, 1709, 1803, 1809, 1903), Windows 7, Windows 8.1, Windows RT 8.1, Windows Server 2008 (including R2), Windows Server 2012 (including R2), Windows Server 2016, Windows Server 2019, and Windows Server versions 1803 and 1903.
- If immediate patching is not feasible, implement strict access controls to limit local logon privileges and enforce the principle of least privilege. Restrict access to the CLFS driver by limiting which processes can interact with the Common Log File System.
- Monitor for indicators of privilege escalation activity, including unexpected SYSTEM-level process creation from low-privileged accounts, suspicious CLFS log file operations, and anomalous kernel-mode driver behavior. Deploy endpoint detection and response (EDR) solutions with kernel exploit detection capabilities.
- For systems running end-of-life Windows versions (Windows 7, Windows Server 2008), prioritize migration to supported operating systems. Implement network segmentation to isolate legacy systems and reduce the blast radius of a potential compromise.
Technical Details
CVE-2019-1214 exploits an improper memory buffer handling weakness (CWE-119) in the Windows Common Log File System (CLFS) driver. The CLFS driver, responsible for managing transaction logging in Windows, fails to properly validate or restrict operations on memory objects, creating a buffer boundary violation that can be leveraged for privilege escalation. The CVSS vector (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates that the attack requires local access with low-level privileges but no user interaction, with high impact across all security objectives. The vulnerability affects the core Windows CLFS subsystem, which is present in all supported Windows desktop and server editions, making the attack surface extremely broad. This vulnerability is distinct from other CLFS driver flaws and specifically targets the object handling logic within the driver's memory management routines.
Frequently Asked Questions
Is CVE-2019-1214 being actively exploited?
Yes. CVE-2019-1214 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The EPSS score of 3.68% (87.8th percentile) indicates a notable exploitation probability. The Windows CLFS driver has been a recurring target for privilege escalation attacks.
What products are affected by CVE-2019-1214?
CVE-2019-1214 affects a wide range of Windows operating systems: Windows 10 (versions 1507, 1607, 1703, 1709, 1803, 1809, 1903), Windows 7, Windows 8.1, Windows RT 8.1, Windows Server 2008 (including R2), Windows Server 2012 (including R2), Windows Server 2016, Windows Server 2019, and Windows Server versions 1803 and 1903.
How do I fix CVE-2019-1214?
Apply the September 2019 security updates provided by Microsoft for all affected Windows versions. For end-of-life systems like Windows 7 and Windows Server 2008, prioritize migration to supported operating systems. In the interim, restrict local access privileges and deploy EDR solutions to detect exploitation attempts.
How severe is CVE-2019-1214?
CVE-2019-1214 has a CVSS 3.1 score of 7.8 (HIGH). While it requires local access with low privileges, the lack of user interaction requirement and high impact across confidentiality, integrity, and availability make it a significant threat. The wide range of affected Windows versions amplifies the organizational risk.
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