CVE-2019-1458
Microsoft Win32k Privilege Escalation Vulnerability
Description
CVE-2019-1458 is a high-severity elevation of privilege vulnerability in the Microsoft Windows Win32k component. The flaw arises when Win32k fails to properly handle objects in memory, allowing a locally authenticated attacker to execute arbitrary code in kernel mode. An attacker who successfully exploits CVE-2019-1458 could install programs, view or modify data, or create new accounts with full administrative rights. This vulnerability is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog with confirmed active exploitation, and it has been associated with ransomware campaigns. With an EPSS score of 91.94% (99.7th percentile), the Microsoft Win32k privilege escalation vulnerability represents a near-certain exploitation risk.
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 7 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows server 2016 | - |
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
- http://packetstormsecurity.com/files/156651/Microsoft-Windows-WizardOpium-Local-Privilege-Escalation.html(Exploit, Third Party Advisory, VDB Entry)
- http://packetstormsecurity.com/files/159569/Microsoft-Windows-Uninitialized-Variable-Local-Privilege-Escalation.html(Exploit, Third Party Advisory, VDB Entry)
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1458(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1458(US Government Resource)
Weakness Type
CWE-269: Improper Privilege Management
The Win32k elevation of privilege vulnerability in CVE-2019-1458 stems from improper handling of objects in memory within the Windows kernel-mode driver. When Win32k processes certain operations, it fails to correctly manage memory objects, allowing a local attacker with low-level access to escalate their privileges to kernel level. This type of weakness enables attackers to bypass operating system security boundaries and gain complete control over the affected system.
Learn more: CWE-269 — Improper Privilege Management
Impact Analysis
CVE-2019-1458 carries a CVSS 3.1 base score of 7.8 (HIGH), indicating a serious privilege escalation threat on affected Windows systems. The attack vector is local, requiring the attacker to already have some level of access to the target system, but the attack complexity is low and no user interaction is needed once local access is obtained. Only low-level privileges are required to trigger the vulnerability, making it an ideal post-exploitation tool for elevating access from a standard user to full SYSTEM-level control. Successful exploitation compromises confidentiality, integrity, and availability at the highest level, giving the attacker kernel-mode code execution. Critically, this vulnerability is known to be used in ransomware campaigns, significantly increasing the operational risk for organizations with unpatched Windows systems. The EPSS score of 91.94% places CVE-2019-1458 in the 99.7th percentile, indicating near-certain exploitation in the wild.
Exploit Maturity
Public exploit code is available for CVE-2019-1458 via Packet Storm Security and an additional exploit variant. CISA has confirmed active exploitation in the wild by including this vulnerability in the KEV catalog, and ransomware operators are known to leverage CVE-2019-1458 as part of their attack chains. The EPSS score of 91.94% (99.7th percentile) indicates near-certain exploitation activity. This vulnerability was notably linked to the "WizardOpium" campaign, where it was chained with a Chrome zero-day (CVE-2019-13720) to achieve full system compromise through browser-based attacks. Federal agencies were required to remediate by 2022-07-10.
Remediation
- Apply Microsoft security updates immediately as directed by CISA KEV: "Apply updates per vendor instructions." Install the December 2019 Patch Tuesday update (KB4530702 and related patches) for all affected Windows versions through Windows Update or WSUS.
- Verify all affected Windows versions are patched, including Windows 7, Windows 8.1, Windows 10 (1507, 1607), Windows RT 8.1, Windows Server 2008 (including R2), Windows Server 2012 (including R2), and Windows Server 2016. Use vulnerability scanning tools to confirm no instances remain unpatched.
- Implement least privilege principles by ensuring standard users do not have local administrator rights. Since CVE-2019-1458 requires local access with low privileges, restricting user permissions and enforcing application whitelisting can reduce the attack surface.
- Deploy endpoint detection and response (EDR) solutions to monitor for kernel-mode exploitation attempts, suspicious Win32k system calls, and privilege escalation indicators. Review logs for unusual process creation events running as SYSTEM originating from low-privilege user sessions.
- Prioritize migration from end-of-life Windows versions such as Windows 7 and Windows Server 2008 that are affected by this vulnerability. Unsupported operating systems will not receive future security patches, leaving them permanently exposed to this and similar kernel-level exploits.
Technical Details
CVE-2019-1458 is an elevation of privilege vulnerability in the Win32k kernel-mode driver, which handles window management and graphics operations in Microsoft Windows. The flaw occurs when Win32k fails to properly handle objects in memory during certain window management operations, leading to an exploitable condition where a local attacker can execute arbitrary code in kernel mode. The CVSS vector (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) reflects that the attack requires local access and low privileges but involves no user interaction and low complexity. The vulnerability was discovered as part of the "WizardOpium" attack chain, where attackers first exploited a Chrome use-after-free vulnerability (CVE-2019-13720) to gain initial code execution in the browser sandbox, then used CVE-2019-1458 to escape the sandbox and achieve SYSTEM-level privileges. The exploit leverages an uninitialized variable in Win32k to manipulate kernel memory structures, ultimately allowing the attacker to overwrite process tokens and elevate privileges from a standard user context to NT AUTHORITYSYSTEM.
Frequently Asked Questions
Is CVE-2019-1458 being actively exploited?
Yes. CVE-2019-1458 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. It has been associated with ransomware campaigns and the "WizardOpium" attack chain. The EPSS score of 91.94% (99.7th percentile) indicates near-certain exploitation.
What products are affected by CVE-2019-1458?
CVE-2019-1458 affects multiple Microsoft Windows versions, including Windows 7, Windows 8.1, Windows 10 (versions 1507 and 1607), Windows RT 8.1, Windows Server 2008 (including R2), Windows Server 2012 (including R2), and Windows Server 2016. All editions of these operating systems are impacted.
How do I fix CVE-2019-1458?
Apply the Microsoft security updates from the December 2019 Patch Tuesday release. Use Windows Update, WSUS, or Microsoft Update Catalog to deploy the relevant patches. Verify all affected endpoints are updated using vulnerability scanning, and prioritize migration from end-of-life Windows versions.
How severe is CVE-2019-1458?
CVE-2019-1458 has a CVSS 3.1 base score of 7.8 (HIGH) and enables local privilege escalation to SYSTEM level. Its confirmed use in ransomware campaigns and the 99.7th percentile EPSS score make it one of the most actively exploited Windows kernel vulnerabilities. Immediate patching is strongly recommended.
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