CVE-2020-1027
Microsoft Windows Kernel Privilege Escalation Vulnerability
Description
CVE-2020-1027 is an elevation of privilege vulnerability in the Windows Kernel caused by improper handling of objects in memory. This vulnerability affects Microsoft Windows systems and allows a local attacker who has already gained initial access to execute code with elevated permissions, potentially achieving full SYSTEM-level control. The vulnerability was added to CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. With an EPSS percentile of 92.7%, CVE-2020-1027 represents a significant threat that organizations running affected Windows versions should remediate immediately.
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 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: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/168068/Windows-sxs-CNodeFactory-XMLParser_Element_doc_assembly_assemblyIdentity-Heap-Buffer-Overflow.html(Exploit, Third Party Advisory, VDB Entry)
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1027(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-1027(US Government Resource)
Weakness Type
CWE-269: Improper Privilege Management
CWE-269 describes weaknesses where a product does not properly assign, modify, track, or check the privileges of an actor, causing the actor to gain more access than intended. In CVE-2020-1027, the Windows Kernel fails to correctly manage privilege boundaries during memory object operations, enabling an attacker to escalate from a lower integrity level to full system-level execution privileges.
Learn more: CWE-269 — Improper Privilege Management
Impact Analysis
CVE-2020-1027 is a locally exploitable elevation of privilege vulnerability in the Windows Kernel that allows an attacker with initial low-privilege access to execute arbitrary code with SYSTEM-level permissions. The attack requires local access to the target system, meaning an attacker must already have a foothold — typically obtained through phishing, a separate remote vulnerability, or malware delivery. Once exploited, the attacker gains full control over the affected system, compromising confidentiality, integrity, and availability of all data and services running on the machine. The EPSS percentile of 92.7% indicates a high probability of exploitation activity, and the inclusion in CISA's KEV catalog confirms that threat actors have leveraged this vulnerability in real-world attacks. Organizations should treat this as a high-priority patching target, especially given the kernel-level access that successful exploitation provides.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2020-1027 in the wild by including it in the Known Exploited Vulnerabilities catalog with a remediation deadline of June 13, 2022. The EPSS percentile of 92.7% indicates a very high probability of exploitation, placing this vulnerability well above typical kernel privilege escalation flaws in terms of real-world exploitation activity. As a Windows Kernel vulnerability, it is commonly used as a post-exploitation tool to gain SYSTEM privileges after initial access has been obtained through other means, making it a valuable component in multi-stage attack chains.
Remediation
- Apply the security updates provided by Microsoft for the affected Windows versions as specified in the associated security advisory. CISA requires federal agencies to remediate by June 13, 2022.
- Prioritize patching on systems that are externally exposed or used by privileged users, as this vulnerability is most dangerous when chained with initial access exploits.
- Implement endpoint detection and response (EDR) solutions configured to detect suspicious kernel-mode activity and privilege escalation attempts, including unusual process token manipulation.
- Review system logs and security event logs for indicators of privilege escalation, particularly events showing unexpected transitions from low-integrity to SYSTEM-level processes.
- Apply the principle of least privilege across all user accounts and services to limit the potential impact if an attacker gains initial foothold access before exploiting this kernel vulnerability.
Technical Details
CVE-2020-1027 stems from a flaw in how the Windows Kernel manages objects in memory, which aligns with improper privilege management weaknesses. When the kernel processes certain memory objects, it fails to properly validate or enforce privilege boundaries, allowing a local attacker to manipulate these objects in a way that elevates their execution context from a low-integrity or user-mode process to SYSTEM-level privileges. The attack is local in nature, meaning an adversary must first achieve code execution on the target system through another vector such as a phishing payload or a remote code execution vulnerability. Once local access is obtained, the attacker triggers the kernel vulnerability to gain full control over the operating system. This type of kernel elevation of privilege is particularly dangerous because it operates below the security boundaries enforced by user-mode protections, making detection difficult without specialized kernel-level monitoring.
Frequently Asked Questions
Is CVE-2020-1027 being actively exploited?
Yes, CVE-2020-1027 is being actively exploited. CISA has added this vulnerability to its Known Exploited Vulnerabilities catalog, confirming real-world exploitation. The EPSS percentile of 92.7% further indicates a high likelihood of exploitation activity.
What products are affected by CVE-2020-1027?
CVE-2020-1027 affects Microsoft Windows operating systems. The vulnerability resides in the Windows Kernel component, and multiple Windows versions are impacted. Administrators should consult Microsoft's security advisory for the specific list of affected OS versions.
How do I fix CVE-2020-1027?
Apply the security updates provided by Microsoft as soon as possible. Prioritize patching on systems with higher exposure risk. Additionally, implement endpoint monitoring to detect privilege escalation attempts while patches are being rolled out.
How severe is CVE-2020-1027?
CVE-2020-1027 is a serious elevation of privilege vulnerability in the Windows Kernel. Its EPSS percentile of 92.7% places it among the most likely-to-be-exploited vulnerabilities. Successful exploitation grants SYSTEM-level access, making it a critical threat that should be remediated promptly.
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