CVE-2020-1027Exploited in the wildNVD status: Analyzed
Microsoft Windows Kernel Privilege Escalation
CVE-2020-1027 is a high-severity out-of-bounds write vulnerability in Windows from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected Windows versions: 10 Version 1803 for 32-bit Systems; 10 Version 1803 for x64-based Systems; 10 Version 1803 for ARM64-based Systems, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on May 23, 2022, which means attacks have been observed in the wild.
Patch now
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Windows you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on portal.msrc.microsoft.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Windows | 10 Version 1803 for 32-bit Systems; 10 Version 1803 for x64-based Systems; 10 Version 1803 for ARM64-based Systems; 10 Version 1809 for 32-bit Systems; 10 Version 1809 for x64-based Systems; 10 Version 1809 for ARM64-based Systems; 10 Version 1709 for 32-bit Systems; 10 Version 1709 for x64-based Systems; and 10 more ranges | Not stated |
| Microsoft | Windows Server | version 1803 (Core Installation); 2019; 2019 (Core installation); 2016; 2016 (Core installation); 2008 for 32-bit Systems Service Pack 2; 2008 for 32-bit Systems Service Pack 2 (Core installation); 2008 for Itanium-Based Systems Service Pack 2; and 7 more ranges | Not stated |
| Microsoft | Windows 10 Version 1909 for 32-bit Systems | Not specified in the record | Not stated |
| Microsoft | Windows 10 Version 1909 for x64-based Systems | Not specified in the record | Not stated |
| Microsoft | Windows 10 Version 1909 for ARM64-based Systems | Not specified in the record | Not stated |
| Microsoft | Windows Server, version 1909 (Server Core installation) | Not specified in the record | Not stated |
| Microsoft | Windows 10 Version 1903 for 32-bit Systems | Not specified in the record | Not stated |
| Microsoft | Windows 10 Version 1903 for x64-based Systems | Not specified in the record | Not stated |
| Microsoft | Windows 10 Version 1903 for ARM64-based Systems | Not specified in the record | Not stated |
| Microsoft | Windows Server, version 1903 (Server Core installation) | Not specified in the record | Not stated |
| Microsoft | Windows 10 1507 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1607 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1709 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1803 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1809 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1903 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1909 | Not specified in the record | Not stated |
| Microsoft | Windows 7 | Not specified in the record | Not stated |
| Microsoft | Windows 8.1 | Not specified in the record | Not stated |
| Microsoft | Windows Rt 8.1 | Not specified in the record | Not stated |
| Microsoft | Windows Server 1803 | Not specified in the record | Not stated |
| Microsoft | Windows Server 1903 | Not specified in the record | Not stated |
| Microsoft | Windows Server 1909 | Not specified in the record | Not stated |
| Microsoft | Windows Server 2008 | r2 | Not stated |
| Microsoft | Windows Server 2012 | r2 | Not stated |
Version data comes from the organisation that assigned the CVE; 2 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 2.0 | 7.2 | High | NVD |
Official description
An elevation of privilege vulnerability exists in the way that the Windows Kernel handles objects in memory, aka 'Windows Kernel Elevation of Privilege Vulnerability'. This CVE ID is unique from CVE-2020-0913, CVE-2020-1000, CVE-2020-1003.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-1027US Government Resource
Technical write-ups (may include proof of concept)
- packetstormsecurity.com/files/168068/Windows-sxs-CNodeFactory-XMLParser_Element_doc_assembly_assemblyIdentity…Exploit, Third Party Advisory, VDB Entry
Other vulnerabilities in Windows
- 7.4 High severity
- 7.4 High severity
- 7.8 High severity
- 7.5 High severity
- 7.0 High severity
- 7.8 High severity
Recent Out-of-bounds Write vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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