Microsoft October 2021 Patch Tuesday Fixes 4 Zero-days, 71 Flaws

Today is Microsoft’s October 2021 Patch Tuesday, and with it comes fixes for four zero-day vulnerabilities and a total of 74 flaws.

Microsoft has fixed 74 vulnerabilities (81 including Microsoft Edge) with today’s update, with three classified as Critical, and 70 as Important, and one as Low.

These 81 vulnerabilities (including Microsoft Edge) are classified as:

• 21 Elevation of Privilege Vulnerabilities
• 6 Security Feature Bypass Vulnerabilities
• 20 Remote Code Execution Vulnerabilities
• 13 Information Disclosure Vulnerabilities
• 5 Denial of Service Vulnerabilities
• 9 Spoofing Vulnerabilities

For information about the non-security Windows updates, you can read about today’s Windows 11 KB5006674 cumulative update and the Windows 10 updates KB5006670 & KB5006667 cumulative updates.

Also Read: What Does A Data Protection Officer Do? 5 Main Things

Four zero-days fixed, with one actively exploited

October’s Patch Tuesday includes fixes for four zero-day vulnerabilities, with a Win32k Elevation of Privilege Vulnerability vulnerability known to have been actively exploited in attacks.

Microsoft classifies a vulnerability as a zero-day if it is publicly disclosed or actively exploited with no official fix available.

The actively exploited vulnerability was discovered by Kaspersk’s Boris Larin (oct0xor) and allows malware or a threat actor to gain elevated privileges on a Windows device.

• CVE-2021-40449 – Win32k Elevation of Privilege Vulnerability

Kaspersky disclosed today that the vulnerability was used by threat actors in “widespread espionage campaigns against IT companies, military/defense contractors, and diplomatic entities.” 

As part of the attacks, the threat actors installed a remote access trojan (RAT) that was elevated with higher permissions using the zero-day Windows vulnerability. 

Kaspersky calls this cluster of malicious activity MysterSnail and is attributed to the IronHusky and Chinese-speaking APT activity.

Microsoft also fixed three other publicly disclosed vulnerabilities that are not known to be exploited in attacks.

• CVE-2021-40469 – Windows DNS Server Remote Code Execution Vulnerability
• CVE-2021-41335 – Windows Kernel Elevation of Privilege Vulnerability
• CVE-2021-41338 – Windows AppContainer Firewall Rules Security Feature Bypass Vulnerability

Recent updates from other companies

Other vendors who released updates in July include:

• Adobe’s October security updates were released for various applications.
• Android’s October security updates were released last week.
• Apache released HTTP Web Server 2.4.51 to fix an incompete patch for an actively exploited vulnerability.
• Apple released security updates for iOS and iPadOS yesterday that an actively exploited zero-day vulnerability.
• Cisco released security updates for numerous products this month.
• SAP released its October 2021 security updates.
• VMware released a two security updates [1. 2, 3]  for VMware vRealize Operations.

The October 2021 Patch Tuesday Security Updates

Below is the complete list of resolved vulnerabilities and released advisories in the October 2021 Patch Tuesday updates. To access the full description of each vulnerability and the systems that it affects, you can view the full report here.

Also Read: The DNC Registry Singapore: 5 Things You Must Know

Tag	CVE ID	CVE Title	Severity
.NET Core & Visual Studio	CVE-2021-41355	.NET Core and Visual Studio Information Disclosure Vulnerability	Important
Active Directory Federation Services	CVE-2021-41361	Active Directory Federation Server Spoofing Vulnerability	Important
Console Window Host	CVE-2021-41346	Console Window Host Security Feature Bypass Vulnerability	Important
HTTP.sys	CVE-2021-26442	Windows HTTP.sys Elevation of Privilege Vulnerability	Important
Microsoft DWM Core Library	CVE-2021-41339	Microsoft DWM Core Library Elevation of Privilege Vulnerability	Important
Microsoft Dynamics	CVE-2021-40457	Microsoft Dynamics 365 Customer Engagement Cross-Site Scripting Vulnerability	Important
Microsoft Dynamics	CVE-2021-41353	Microsoft Dynamics 365 (on-premises) Spoofing Vulnerability	Important
Microsoft Dynamics	CVE-2021-41354	Microsoft Dynamics 365 (on-premises) Cross-site Scripting Vulnerability	Important
Microsoft Edge (Chromium-based)	CVE-2021-37978	Chromium: CVE-2021-37978 Heap buffer overflow in Blink	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37979	Chromium: CVE-2021-37979 Heap buffer overflow in WebRTC	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37980	Chromium: CVE-2021-37980 Inappropriate implementation in Sandbox	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37977	Chromium: CVE-2021-37977 Use after free in Garbage Collection	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37974	Chromium: CVE-2021-37974 Use after free in Safe Browsing	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37975	Chromium: CVE-2021-37975 Use after free in V8	Unknown
Microsoft Edge (Chromium-based)	CVE-2021-37976	Chromium: CVE-2021-37976 Information leak in core	Unknown
Microsoft Exchange Server	CVE-2021-26427	Microsoft Exchange Server Remote Code Execution Vulnerability	Important
Microsoft Exchange Server	CVE-2021-34453	Microsoft Exchange Server Denial of Service Vulnerability	Important
Microsoft Exchange Server	CVE-2021-41348	Microsoft Exchange Server Elevation of Privilege Vulnerability	Important
Microsoft Exchange Server	CVE-2021-41350	Microsoft Exchange Server Spoofing Vulnerability	Important
Microsoft Graphics Component	CVE-2021-41340	Windows Graphics Component Remote Code Execution Vulnerability	Important
Microsoft Intune	CVE-2021-41363	Intune Management Extension Security Feature Bypass Vulnerability	Important
Microsoft Office Excel	CVE-2021-40473	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-40472	Microsoft Excel Information Disclosure Vulnerability	Important
Microsoft Office Excel	CVE-2021-40471	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-40474	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-40485	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-40479	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-40487	Microsoft SharePoint Server Remote Code Execution Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-40483	Microsoft SharePoint Server Spoofing Vulnerability	Low
Microsoft Office SharePoint	CVE-2021-40484	Microsoft SharePoint Server Spoofing Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-40482	Microsoft SharePoint Server Information Disclosure Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-41344	Microsoft SharePoint Server Remote Code Execution Vulnerability	Important
Microsoft Office Visio	CVE-2021-40480	Microsoft Office Visio Remote Code Execution Vulnerability	Important
Microsoft Office Visio	CVE-2021-40481	Microsoft Office Visio Remote Code Execution Vulnerability	Important
Microsoft Office Word	CVE-2021-40486	Microsoft Word Remote Code Execution Vulnerability	Critical
Microsoft Windows Codecs Library	CVE-2021-40462	Windows Media Foundation Dolby Digital Atmos Decoders Remote Code Execution Vulnerability	Important
Microsoft Windows Codecs Library	CVE-2021-41330	Microsoft Windows Media Foundation Remote Code Execution Vulnerability	Important
Microsoft Windows Codecs Library	CVE-2021-41331	Windows Media Audio Decoder Remote Code Execution Vulnerability	Important
Rich Text Edit Control	CVE-2021-40454	Rich Text Edit Control Information Disclosure Vulnerability	Important
Role: DNS Server	CVE-2021-40469	Windows DNS Server Remote Code Execution Vulnerability	Important
Role: Windows Active Directory Server	CVE-2021-41337	Active Directory Security Feature Bypass Vulnerability	Important
Role: Windows AD FS Server	CVE-2021-40456	Windows AD FS Security Feature Bypass Vulnerability	Important
Role: Windows Hyper-V	CVE-2021-40461	Windows Hyper-V Remote Code Execution Vulnerability	Critical
Role: Windows Hyper-V	CVE-2021-38672	Windows Hyper-V Remote Code Execution Vulnerability	Critical
System Center	CVE-2021-41352	SCOM Information Disclosure Vulnerability	Important
Visual Studio	CVE-2020-1971	OpenSSL: CVE-2020-1971 EDIPARTYNAME NULL pointer de-reference	Important
Visual Studio	CVE-2021-3450	OpenSSL: CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT	Important
Visual Studio	CVE-2021-3449	OpenSSL: CVE-2021-3449 NULL pointer deref in signature_algorithms processing	Important
Windows AppContainer	CVE-2021-41338	Windows AppContainer Firewall Rules Security Feature Bypass Vulnerability	Important
Windows AppContainer	CVE-2021-40476	Windows AppContainer Elevation Of Privilege Vulnerability	Important
Windows AppX Deployment Service	CVE-2021-41347	Windows AppX Deployment Service Elevation of Privilege Vulnerability	Important
Windows Bind Filter Driver	CVE-2021-40468	Windows Bind Filter Driver Information Disclosure Vulnerability	Important
Windows Cloud Files Mini Filter Driver	CVE-2021-40475	Windows Cloud Files Mini Filter Driver Information Disclosure Vulnerability	Important
Windows Common Log File System Driver	CVE-2021-40443	Windows Common Log File System Driver Elevation of Privilege Vulnerability	Important
Windows Common Log File System Driver	CVE-2021-40467	Windows Common Log File System Driver Elevation of Privilege Vulnerability	Important
Windows Common Log File System Driver	CVE-2021-40466	Windows Common Log File System Driver Elevation of Privilege Vulnerability	Important
Windows Desktop Bridge	CVE-2021-41334	Windows Desktop Bridge Elevation of Privilege Vulnerability	Important
Windows DirectX	CVE-2021-40470	DirectX Graphics Kernel Elevation of Privilege Vulnerability	Important
Windows Event Tracing	CVE-2021-40477	Windows Event Tracing Elevation of Privilege Vulnerability	Important
Windows exFAT File System	CVE-2021-38663	Windows exFAT File System Information Disclosure Vulnerability	Important
Windows Fastfat Driver	CVE-2021-41343	Windows Fast FAT File System Driver Information Disclosure Vulnerability	Important
Windows Fastfat Driver	CVE-2021-38662	Windows Fast FAT File System Driver Information Disclosure Vulnerability	Important
Windows Installer	CVE-2021-40455	Windows Installer Spoofing Vulnerability	Important
Windows Kernel	CVE-2021-41336	Windows Kernel Information Disclosure Vulnerability	Important
Windows Kernel	CVE-2021-41335	Windows Kernel Elevation of Privilege Vulnerability	Important
Windows MSHTML Platform	CVE-2021-41342	Windows MSHTML Platform Remote Code Execution Vulnerability	Important
Windows Nearby Sharing	CVE-2021-40464	Windows Nearby Sharing Elevation of Privilege Vulnerability	Important
Windows Network Address Translation (NAT)	CVE-2021-40463	Windows NAT Denial of Service Vulnerability	Important
Windows Print Spooler Components	CVE-2021-41332	Windows Print Spooler Information Disclosure Vulnerability	Important
Windows Print Spooler Components	CVE-2021-36970	Windows Print Spooler Spoofing Vulnerability	Important
Windows Remote Procedure Call Runtime	CVE-2021-40460	Windows Remote Procedure Call Runtime Security Feature Bypass Vulnerability	Important
Windows Storage Spaces Controller	CVE-2021-40489	Storage Spaces Controller Elevation of Privilege Vulnerability	Important
Windows Storage Spaces Controller	CVE-2021-41345	Storage Spaces Controller Elevation of Privilege Vulnerability	Important
Windows Storage Spaces Controller	CVE-2021-26441	Storage Spaces Controller Elevation of Privilege Vulnerability	Important
Windows Storage Spaces Controller	CVE-2021-40478	Storage Spaces Controller Elevation of Privilege Vulnerability	Important
Windows Storage Spaces Controller	CVE-2021-40488	Storage Spaces Controller Elevation of Privilege Vulnerability	Important
Windows TCP/IP	CVE-2021-36953	Windows TCP/IP Denial of Service Vulnerability	Important
Windows Text Shaping	CVE-2021-40465	Windows Text Shaping Remote Code Execution Vulnerability	Important
Windows Win32K	CVE-2021-40449	Win32k Elevation of Privilege Vulnerability	Important
Windows Win32K	CVE-2021-41357	Win32k Elevation of Privilege Vulnerability	Important
Windows Win32K	CVE-2021-40450	Win32k Elevation of Privilege Vulnerability	Important