Vulnerability Description
On February 10, 2021, Beijing time, Microsoft released February 2021 Security Updates that fix 56 vulnerabilities, including high-risk ones like remote code execution and privilege escalation in various widely used products such as Microsoft Windows, Microsoft Office, Microsoft Exchange Server, Visual Studio, and Microsoft .NET Framework.
In these security updates, Microsoft fixes 11 critical vulnerabilities and 43 important ones.
Affected users are advised to apply patches. For details, please refer to Appendix: Vulnerability List.
Reference link: https://msrc.microsoft.com/update-guide/releaseNote/2021-Feb
Description of Critical Vulnerabilities
Based on the product popularity and vulnerability importance, we have selected the vulnerabilities with a huge impact from the updates for affected users.
Windows Installer privilege escalation vulnerability (CVE-2021-1727)
This vulnerability (CVE-2020-16902) is a patch bypass one which allows attackers with access to a low-privileged user account to escalate privileges to gain control of the target host. Currently, the vulnerability exploitation method has been made publicly available.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-1727
Windows Win32k privilege escalation vulnerability (CVE-2021-1732)
Windows Kernel-Mode Driver is prone to a privilege escalation vulnerability due to the improper handling of objects in memory. Unauthenticated local attackers could exploit this vulnerability to execute arbitrary code with escalated privileges on the target system. According to our data, this vulnerability has been exploited in the wild.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-1732
Windows TCP/IP Remote Code Execution Vulnerability (CVE-2021-24074)
The IPv4 stack in Windows contains a remote code execution vulnerability which allows remote attackers, via a crafted packet, to execute arbitrary code on the target host.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24074
Windows DNS Server Remote Code Execution Vulnerability (CVE-2021-24078)
By sending a crafted packet to a vulnerable DNS server, an unauthenticated attacker could exploit this vulnerability to execute arbitrary code with privileges of a local system account on the target system.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24078
Windows TCP/IP Denial-of-Service Vulnerability (CVE-2021-24086)
The IPv6 stack in Windows is prone to a denial-of-service vulnerability which allows remote attackers to cause a denial of service against the target system by sending a crafted packet to an affected host.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24086
Windows TCP/IP Remote Code Execution Vulnerability (CVE-2021-24094)
The IPv6 stack in Windows contains a remote code execution vulnerability which allows remote attackers, via a crafted packet, to execute arbitrary code on the target host.
For details of this vulnerability, visit the following link:
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-24094
Windows Console Driver Denial-of-Service Vulnerability (CVE-2021-24098)
ConDrv.sys contains a denial-of-service (DoS) vulnerability which could trigger a blue screen of death (BSOD) on Windows 10 systems. Attackers could trigger this vulnerability by tricking users into clicking a crafted link (included in an email or instant message) and opening a crafted file. Some time ago, the vulnerability exploitation method has been spread widely.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24098
.NET Core Remote Code Execution Vulnerability (CVE-2021-26701)
.NET Core contains a remote code execution vulnerability which allows remote attackers to take control of the target host. Currently, details of this vulnerability have been made publicly available. Users and developers are advised to open and use .NET-related components and applications.
For details of this vulnerability, visit the following link:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-26701
Scope of Impact
The following table lists affected product versions that require special attention. Please view Microsoft’s security updates for other products with the scope of impact of the vulnerabilities.
| Vulnerability ID | Affected Version |
| CVE-2021-1727 | Windows Server 2012 R2 (Server Core installation) Windows Server 2012 R2 Windows Server 2012 (Server Core installation) Windows Server 2012 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) Windows Server 2008 R2 for x64-based Systems Service Pack 1 Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) Windows Server 2008 for x64-based Systems Service Pack 2 Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) Windows Server 2008 for 32-bit Systems Service Pack 2 Windows RT 8.1 Windows 8.1 for x64-based systems Windows 8.1 for 32-bit systems Windows 7 for x64-based Systems Service Pack 1 Windows 7 for 32-bit Systems Service Pack 1 Windows Server 2016 (Server Core installation) Windows Server 2016 Windows 10 Version 1607 for x64-based Systems Windows 10 Version 1607 for 32-bit Systems Windows 10 for x64-based Systems Windows 10 for 32-bit Systems Windows Server, version 20H2 (Server Core Installation) Windows 10 Version 20H2 for ARM64-based Systems Windows 10 Version 20H2 for 32-bit Systems Windows 10 Version 20H2 for x64-based Systems Windows Server, version 2004 (Server Core installation) Windows 10 Version 2004 for x64-based Systems Windows 10 Version 2004 for ARM64-based Systems Windows 10 Version 2004 for 32-bit Systems Windows Server, version 1909 (Server Core installation) Windows 10 Version 1909 for ARM64-based Systems Windows 10 Version 1909 for x64-based Systems Windows 10 Version 1909 for 32-bit Systems Windows Server 2019 (Server Core installation) Windows Server 2019 Windows 10 Version 1809 for ARM64-based Systems Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems Windows 10 Version 1803 for ARM64-based Systems Windows 10 Version 1803 for x64-based Systems Windows 10 Version 1803 for 32-bit Systems |
| CVE-2021-1732 | Windows Server, version 20H2 (Server Core Installation) Windows 10 Version 20H2 for ARM64-based Systems Windows 10 Version 20H2 for 32-bit Systems Windows 10 Version 20H2 for x64-based Systems Windows Server, version 2004 (Server Core installation) Windows 10 Version 2004 for x64-based Systems Windows 10 Version 2004 for ARM64-based Systems Windows 10 Version 2004 for 32-bit Systems Windows Server, version 1909 (Server Core installation) Windows 10 Version 1909 for ARM64-based Systems Windows 10 Version 1909 for x64-based Systems Windows 10 Version 1909 for 32-bit Systems Windows Server 2019 (Server Core installation) Windows Server 2019 Windows 10 Version 1809 for ARM64-based Systems Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems Windows 10 Version 1803 for ARM64-based Systems Windows 10 Version 1803 for x64-based Systems Windows 10 Version 1803 for 32-bit Systems |
| CVE-2021-24078 | Windows Server 2012 R2 (Server Core installation) Windows Server 2012 R2 Windows Server 2012 (Server Core installation) Windows Server 2012 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) Windows Server 2008 R2 for x64-based Systems Service Pack 1 Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) Windows Server 2008 for x64-based Systems Service Pack 2 Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) Windows Server 2008 for 32-bit Systems Service Pack 2 Windows Server 2016 (Server Core installation) Windows Server 2016 Windows Server, version 20H2 (Server Core Installation) Windows Server, version 2004 (Server Core installation) Windows Server, version 1909 (Server Core installation) Windows Server 2019 (Server Core installation) Windows Server 2019 |
| CVE-2021-24074 CVE-2021-24086 CVE-2021-24094 | Windows Server, version 20H2 (Server Core Installation) Windows 10 Version 20H2 for ARM64-based Systems Windows 10 Version 20H2 for 32-bit Systems Windows 10 Version 20H2 for x64-based Systems Windows Server, version 2004 (Server Core installation) Windows 10 Version 2004 for x64-based Systems Windows 10 Version 2004 for ARM64-based Systems Windows 10 Version 2004 for 32-bit Systems Windows Server, version 1909 (Server Core installation) Windows 10 Version 1909 for ARM64-based Systems Windows 10 Version 1909 for x64-based Systems Windows 10 Version 1909 for 32-bit Systems Windows Server 2012 R2 (Server Core installation) Windows Server 2012 R2 Windows Server 2012 (Server Core installation) Windows Server 2012 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) Windows Server 2008 R2 for x64-based Systems Service Pack 1 Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) Windows Server 2008 for x64-based Systems Service Pack 2 Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) Windows Server 2008 for 32-bit Systems Service Pack 2 Windows RT 8.1 Windows 8.1 for x64-based systems Windows 8.1 for 32-bit systems Windows 7 for x64-based Systems Service Pack 1 Windows 7 for 32-bit Systems Service Pack 1 Windows Server 2016 (Server Core installation) Windows Server 2016 Windows 10 Version 1607 for x64-based Systems Windows 10 Version 1607 for 32-bit Systems Windows 10 for x64-based Systems Windows 10 for 32-bit Systems Windows Server 2019 (Server Core installation) Windows Server 2019 Windows 10 Version 1809 for ARM64-based Systems Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems Windows 10 Version 1803 for ARM64-based Systems Windows 10 Version 1803 for x64-based Systems Windows 10 Version 1803 for 32-bit Systems |
| CVE-2021-24098 | Windows Server, version 1909 (Server Core installation) Windows 10 Version 1909 for ARM64-based Systems Windows 10 Version 1909 for x64-based Systems Windows 10 Version 1909 for 32-bit Systems Windows Server 2019 (Server Core installation) Windows Server 2019 Windows 10 Version 1809 for ARM64-based Systems Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems Windows 10 Version 1803 for ARM64-based Systems Windows 10 Version 1803 for x64-based Systems Windows 10 Version 1803 for 32-bit Systems Windows Server, version 20H2 (Server Core Installation) Windows 10 Version 20H2 for ARM64-based Systems Windows 10 Version 20H2 for 32-bit Systems Windows 10 Version 20H2 for x64-based Systems Windows Server, version 2004 (Server Core installation) Windows 10 Version 2004 for x64-based Systems Windows 10 Version 2004 for ARM64-based Systems Windows 10 Version 2004 for 32-bit Systems |
| CVE-2021-26701 | .NET 5.0 .NET Core 3.1 .NET Core 2.1 |
Patch Update
Currently, Microsoft has released security updates to fix the preceding vulnerabilities in product versions supported by Microsoft. Affected users are strongly advised to apply these updates as soon as possible. These updates are available at the following link:
https://msrc.microsoft.com/update-guide/releaseNote/2021-Feb
Note: Windows Update may fail due to network and computer environment issues.
Therefore, users are advised to check whether the patches are successfully updated immediately after installation.
Right-click the Start button and choose Settings (N) > Update & Security > Windows Update to view the message on the page. Alternatively, you can view historical updates by clicking View update history.
If an update fails to be successfully installed, you can click the update name to open the Microsoft’s official update download page. Users are advised to click the links on the page to visit the “Microsoft Update Catalog” website to download and install independent packages.
Statement
This advisory is only used to describe a potential risk. NSFOCUS does not provide any commitment or promise on this advisory. NSFOCUS and the author will not bear any liability for any direct and/or indirect consequences and losses caused by transmitting and/or using this advisory. NSFOCUS reserves all the rights to modify and interpret this advisory. Please include this statement paragraph when reproducing or transferring this advisory. Do not modify this advisory, add/delete any information to/from it, or use this advisory for commercial purposes without permission from NSFOCUS.
About NSFOCUS
NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyberattacks. The company’s Intelligent Hybrid Security strategy utilizes both cloud and on-premises security platforms, built on a foundation of real-time global threat intelligence, to provide multi-layered, unified and dynamic protection against advanced cyber attacks.
NSFOCUS works with Fortune Global 500 companies, including four of the world’s five largest financial institutions, organizations in insurance, retail, healthcare, critical infrastructure industries as well as government agencies. NSFOCUS has technology and channel partners in more than 60 countries, is a member of both the Microsoft Active Protections Program (MAPP), and the Cloud Security Alliance (CSA). A wholly owned subsidiary of NSFOCUS Technologies Group Co., Ltd., the company has operations in the Americas, Europe, the Middle East and Asia Pacific.
