Microsoft February 2021 Patch Tuesday fixes 56 bugs, including an actively exploited Windows zero-day

Pierluigi Paganini February 09, 2021

Microsoft February 2021 Patch Tuesday addresses 56 vulnerabilities, including a flaw that is known to be actively exploited in the wild.

Microsoft February 2021 Patch Tuesday security updates address 56 CVEs in multiple products, including Windows components, .NET Framework, Azure IoT, Azure Kubernetes Service, Microsoft Edge for Android, Exchange Server, Office and Office Services and Web Apps, Skype for Business and Lync, and Windows Defender.

Of these 56 vulnerabilities, 11 have been rated as Critical, 43 as Important, and two as Moderate in severity. Microsoft revealed that one of these flaws is known to be actively exploited in attacks in the wild, while six issues are listed as being publicly known at the time of release.

The CVE-2021-1732 zero-day is an elevation of privilege issues that resides in the Windows Win32k component. The flaw was exploited by threat actors to obtain SYSTEM-level access after gaining access to a Windows system. Microsoft did not disclose details about the attacks that exploited this flaw.

The vulnerability was reported by JinQuan, MaDongZe, TuXiaoYi, and LiHao from DBAPPSecurity Co., Ltd

Another interesting issue addressed by Microsoft with Microsoft February 2021 Patch Tuesday security updates is a Windows DNS Server Remote Code Execution vulnerability tracked as CVE-2021-24078.

“This patch fixes a bug in the Windows DNS Server that could allow remote code execution on affected systems. Fortunately, if your system is not configured to be a DNS server, it is not impacted by this bug. However, for those systems that are configured as DNS servers, this bug allows code execution in a privileged service from a remote, unauthenticated attacker.” reads the description provided by Zero Day Initiative. “This is potentially wormable, although only between DNS servers. Prioritize this update if you depend on Microsoft DNS servers.”

Microsoft also fixed a Windows TCP/IP Remote Code Execution vulnerability (CVE-2021-24074) and a .NET Core and Visual Studio Remote Code Execution vulnerability (CVE-2021-26701).

The details for the following CVE were disclosed online before the release of Microsoft February 2021 Patch Tuesday, but none of them was exploited in attacks in the wild.:

  • CVE-2021-1721 – .NET Core and Visual Studio Denial of Service Vulnerability
  • CVE-2021-1733 – Sysinternals PsExec Elevation of Privilege Vulnerability
  • CVE-2021-26701 – .NET Core Remote Code Execution Vulnerability
  • CVE-2021-1727 – Windows Installer Elevation of Privilege Vulnerability
  • CVE-2021-24098 – Windows Console Driver Denial of Service Vulnerability
  • CVE-2021-24106 – Windows DirectX Information Disclosure Vulnerability

“Today Microsoft released a set of fixes affecting Windows TCP/IP implementation that include two Critical Remote Code Execution (RCE) vulnerabilities (CVE-2021-24074, CVE-2021-24094) and an Important Denial of Service (DoS) vulnerability (CVE-2021-24086).” reads a blog post published by Microsoft. “The two RCE vulnerabilities are complex which make it difficult to create functional exploits, so they are not likely in the short term. We believe attackers will be able to create DoS exploits much more quickly and expect all three issues might be exploited with a DoS attack shortly after release.”

The lists of security updates released by Microsoft is available on the Security Update Guide portal:

TagCVE IDCVE Title
.NET CoreCVE-2021-26701.NET Core Remote Code Execution Vulnerability
.NET CoreCVE-2021-24112.NET Core Remote Code Execution Vulnerability
.NET Core & Visual StudioCVE-2021-1721.NET Core and Visual Studio Denial of Service Vulnerability
.NET FrameworkCVE-2021-24111.NET Framework Denial of Service Vulnerability
Azure IoTCVE-2021-24087Azure IoT CLI extension Elevation of Privilege Vulnerability
Developer ToolsCVE-2021-24105Package Managers Configurations Remote Code Execution Vulnerability
Microsoft Azure Kubernetes ServiceCVE-2021-24109Microsoft Azure Kubernetes Service Elevation of Privilege Vulnerability
Microsoft DynamicsCVE-2021-24101Microsoft Dataverse Information Disclosure Vulnerability
Microsoft DynamicsCVE-2021-1724Microsoft Dynamics Business Central Cross-site Scripting Vulnerability
Microsoft Edge for AndroidCVE-2021-24100Microsoft Edge for Android Information Disclosure Vulnerability
Microsoft Exchange ServerCVE-2021-24085Microsoft Exchange Server Spoofing Vulnerability
Microsoft Exchange ServerCVE-2021-1730Microsoft Exchange Server Spoofing Vulnerability
Microsoft Graphics ComponentCVE-2021-24093Windows Graphics Component Remote Code Execution Vulnerability
Microsoft Office ExcelCVE-2021-24067Microsoft Excel Remote Code Execution Vulnerability
Microsoft Office ExcelCVE-2021-24068Microsoft Excel Remote Code Execution Vulnerability
Microsoft Office ExcelCVE-2021-24069Microsoft Excel Remote Code Execution Vulnerability
Microsoft Office ExcelCVE-2021-24070Microsoft Excel Remote Code Execution Vulnerability
Microsoft Office SharePointCVE-2021-24071Microsoft SharePoint Information Disclosure Vulnerability
Microsoft Office SharePointCVE-2021-1726Microsoft SharePoint Spoofing Vulnerability
Microsoft Office SharePointCVE-2021-24066Microsoft SharePoint Remote Code Execution Vulnerability
Microsoft Office SharePointCVE-2021-24072Microsoft SharePoint Server Remote Code Execution Vulnerability
Microsoft TeamsCVE-2021-24114Microsoft Teams iOS Information Disclosure Vulnerability
Microsoft Windows Codecs LibraryCVE-2021-24081Microsoft Windows Codecs Library Remote Code Execution Vulnerability
Microsoft Windows Codecs LibraryCVE-2021-24091Windows Camera Codec Pack Remote Code Execution Vulnerability
Role: DNS ServerCVE-2021-24078Windows DNS Server Remote Code Execution Vulnerability
Role: Hyper-VCVE-2021-24076Microsoft Windows VMSwitch Information Disclosure Vulnerability
Role: Windows Fax ServiceCVE-2021-24077Windows Fax Service Remote Code Execution Vulnerability
Role: Windows Fax ServiceCVE-2021-1722Windows Fax Service Remote Code Execution Vulnerability
Skype for BusinessCVE-2021-24073Skype for Business and Lync Spoofing Vulnerability
Skype for BusinessCVE-2021-24099Skype for Business and Lync Denial of Service Vulnerability
SysInternalsCVE-2021-1733Sysinternals PsExec Elevation of Privilege Vulnerability
System CenterCVE-2021-1728System Center Operations Manager Elevation of Privilege Vulnerability
Visual StudioCVE-2021-1639Visual Studio Code Remote Code Execution Vulnerability
Visual Studio CodeCVE-2021-26700Visual Studio Code npm-script Extension Remote Code Execution Vulnerability
Windows Address BookCVE-2021-24083Windows Address Book Remote Code Execution Vulnerability
Windows Backup EngineCVE-2021-24079Windows Backup Engine Information Disclosure Vulnerability
Windows Console DriverCVE-2021-24098Windows Console Driver Denial of Service Vulnerability
Windows DefenderCVE-2021-24092Microsoft Defender Elevation of Privilege Vulnerability
Windows DirectXCVE-2021-24106Windows DirectX Information Disclosure Vulnerability
Windows Event TracingCVE-2021-24102Windows Event Tracing Elevation of Privilege Vulnerability
Windows Event TracingCVE-2021-24103Windows Event Tracing Elevation of Privilege Vulnerability
Windows InstallerCVE-2021-1727Windows Installer Elevation of Privilege Vulnerability
Windows KernelCVE-2021-24096Windows Kernel Elevation of Privilege Vulnerability
Windows KernelCVE-2021-1732Windows Win32k Elevation of Privilege Vulnerability
Windows KernelCVE-2021-1698Windows Win32k Elevation of Privilege Vulnerability
Windows Mobile Device ManagementCVE-2021-24084Windows Mobile Device Management Information Disclosure Vulnerability
Windows Network File SystemCVE-2021-24075Windows Network File System Denial of Service Vulnerability
Windows PFX EncryptionCVE-2021-1731PFX Encryption Security Feature Bypass Vulnerability
Windows PKU2UCVE-2021-25195Windows PKU2U Elevation of Privilege Vulnerability
Windows PowerShellCVE-2021-24082Microsoft.PowerShell.Utility Module WDAC Security Feature Bypass Vulnerability
Windows Print Spooler ComponentsCVE-2021-24088Windows Local Spooler Remote Code Execution Vulnerability
Windows Remote Procedure CallCVE-2021-1734Windows Remote Procedure Call Information Disclosure Vulnerability
Windows TCP/IPCVE-2021-24086Windows TCP/IP Denial of Service Vulnerability
Windows TCP/IPCVE-2021-24074Windows TCP/IP Remote Code Execution Vulnerability
Windows TCP/IPCVE-2021-24094Windows TCP/IP Remote Code Execution Vulnerability
Windows Trust Verification APICVE-2021-24080Windows Trust Verification API Denial of Service Vulnerability

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Pierluigi Paganini

(SecurityAffairs – hacking, Windows)

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