CVE-2020-1054
Microsoft Win32k Privilege Escalation Vulnerability
Description
CVE-2020-1054 is a high-severity privilege escalation vulnerability in the Microsoft Win32k kernel-mode driver. The vulnerability arises when the Windows kernel-mode driver fails to properly handle objects in memory, allowing an attacker with local access to execute arbitrary code in kernel mode. This out-of-bounds write flaw affects a wide range of Microsoft Windows versions including Windows 7, Windows 8.1, Windows 10, and multiple Windows Server editions. CISA has listed CVE-2020-1054 in its Known Exploited Vulnerabilities catalog, and the EPSS score of 80.9% (99.1st percentile) indicates a very high probability of active exploitation in the wild.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:H/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 1709 | - |
| microsoft | windows 10 1803 | - |
| microsoft | windows 10 1809 | - |
| microsoft | windows 10 1903 | - |
| microsoft | windows 10 1909 | - |
| microsoft | windows 7 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 1803 | - |
| microsoft | windows server 1903 | - |
| microsoft | windows server 1909 | - |
| 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:H/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
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-1054
- http://packetstormsecurity.com/files/160515/Microsoft-Windows-DrawIconEx-Local-Privilege-Escalation.html(Exploit, Third Party Advisory, VDB Entry)
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1054(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-1054(US Government Resource)
Weakness Type
CWE-787: Out-of-bounds Write
Out-of-bounds write vulnerabilities occur when software writes data past the boundaries of allocated memory buffers. In the context of CVE-2020-1054, the Win32k kernel-mode driver improperly handles objects in memory, leading to an out-of-bounds write condition that enables privilege escalation to kernel mode.
Learn more: CWE-787 — Out-of-bounds Write
Impact Analysis
CVE-2020-1054 carries a CVSS 3.1 score of 7.8 (HIGH), reflecting significant risk despite requiring local access for exploitation. The attack complexity is low and only low-level privileges are required, meaning any authenticated local user could potentially exploit this vulnerability without any user interaction. Confidentiality (High): successful exploitation grants kernel-mode execution, allowing full access to sensitive system data. Integrity (High): an attacker can modify any system files and configurations at the kernel level. Availability (High): kernel-mode code execution can lead to complete system compromise or denial of service. The EPSS score of 80.9% places this vulnerability in the 99.1st percentile, indicating near-certain exploitation activity in real-world environments.
Exploit Maturity
CVE-2020-1054 has a mature exploit landscape with confirmed active exploitation. Public exploit code is available for this vulnerability via Packet Storm Security, providing a working local privilege escalation exploit targeting the DrawIconEx function. CISA has confirmed active exploitation in the wild by including CVE-2020-1054 in its Known Exploited Vulnerabilities catalog, with a remediation deadline of 2022-05-03. The EPSS score of 80.9% (99.1st percentile) indicates near-certain exploitation activity. This vulnerability is closely related to CVE-2020-1143, another Win32k elevation of privilege flaw, and attackers may chain these vulnerabilities for broader system compromise.
Remediation
- Apply Microsoft security updates immediately as required by CISA KEV: Apply updates per vendor instructions. The relevant patches are available via the Microsoft Security Response Center.
- Verify that all affected Windows versions have been patched, including Windows 7, Windows 8.1, Windows 10 (all builds from 1507 through 1909), Windows RT 8.1, and Windows Server editions (2008, 2008 R2, 2012, 2012 R2, 2016, 2019, and Server SAC releases 1803, 1903, 1909).
- Restrict local access to critical systems by enforcing the principle of least privilege, limiting which users can log in interactively to workstations and servers.
- Deploy endpoint detection and response (EDR) solutions to monitor for suspicious kernel-mode activity, privilege escalation attempts, and anomalous Win32k driver behavior.
- Implement application whitelisting and code integrity policies to prevent unauthorized executables from running, reducing the likelihood of an attacker leveraging this vulnerability after initial access.
Technical Details
CVE-2020-1054 is an out-of-bounds write vulnerability in the Windows Win32k kernel-mode driver, specifically in the handling of the DrawIconEx function. The flaw occurs when the driver fails to properly validate memory objects, allowing an attacker to write data beyond allocated buffer boundaries in kernel memory. The CVSS vector (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) confirms that exploitation requires local access with low privileges and no user interaction, but yields full compromise of confidentiality, integrity, and availability within the vulnerable component. The scope remains unchanged, meaning the impact is contained to the Win32k component context, though kernel-mode execution effectively grants control over the entire system.
Frequently Asked Questions
Is CVE-2020-1054 being actively exploited?
Yes. CVE-2020-1054 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The EPSS score of 80.9% (99.1st percentile) further indicates a very high probability of exploitation. Public exploit code is readily available.
What products are affected by CVE-2020-1054?
CVE-2020-1054 affects a broad range of Microsoft Windows products including Windows 7, Windows 8.1, Windows RT 8.1, Windows 10 (versions 1507, 1607, 1709, 1803, 1809, 1903, 1909), and Windows Server editions (2008, 2008 R2, 2012, 2012 R2, 2016, 2019, and Server SAC releases 1803, 1903, 1909).
How do I fix CVE-2020-1054?
Apply the security updates provided by Microsoft through the Microsoft Security Response Center advisory. Ensure all affected Windows systems are patched, restrict local access using least-privilege principles, and deploy EDR solutions to monitor for exploitation attempts.
How severe is CVE-2020-1054?
CVE-2020-1054 has a CVSS 3.1 score of 7.8 (HIGH). With an EPSS score of 80.9% in the 99.1st percentile and confirmed active exploitation, this vulnerability poses a significant risk and requires immediate remediation.
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