Patch Tuesday: April 2021 - Security Boulevard

Patch Tuesday: April 2021

On Tuesday, April 13, 2020, Microsoft released its monthly set of software security patches. This month, 108 software vulnerabilities have been remediated with 19 of them being rated “critical” and 88 being rated as “important” and one as “moderate” in severity.

The list includes patches for four new critical vulnerabilities in Microsoft Exchange Server with CVE IDs CVE-2021-28480, CVE-2021-28481, CVE-2021-28482, CVE-2021-28483. As noted in Microsoft’s blog, they recommend that customers prioritize (i.e. update as soon as possible) patches for critical vulnerabilities, including patches for these new vulnerabilities in on-premises Exchange Servers.

Microsoft had previously released emergency, out-of-band patches for four zero-day vulnerabilities in Exchange Server on March 2, 2021. For more details on these earlier vulnerabilities, see this ZDNet article. Microsoft also published a mitigation guide and made available a one-click mitigation tool for these vulnerabilities. Microsoft strongly recommended that customers investigate their Exchange Server deployments to be sure that they haven’t been compromised.

As always, make sure that you have backed up your systems before you apply updates to your software.

The CVE details of the April critical vulnerabilities are listed below:

IDTitleRating
CVE-2021-27095Windows Media Video Decoder Remote Code Execution VulnerabilityCritical
CVE-2021-28315Windows Media Video Decoder Remote Code Execution VulnerabilityCritical
CVE-2021-28329Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28330Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28331Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28332Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28333Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28334Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28335Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28336Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28337Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28338Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28339Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28343Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-28460Azure Sphere Unsigned Code Execution VulnerabilityCritical
CVE-2021-28480Microsoft Exchange Server Remote Code Execution VulnerabilityCritical
CVE-2021-28481Microsoft Exchange Server Remote Code Execution VulnerabilityCritical
CVE-2021-28482Microsoft Exchange Server Remote Code Execution VulnerabilityCritical
CVE-2021-28483Microsoft Exchange Server Remote Code Execution VulnerabilityCritical

Here are the release notes for the April 2021 security updates.

We recommend that all critical patches be deployed within 30 days of release. For detailed information on all 108 vulnerabilities, please visit Microsoft’s Security Update Guide page.


All About Patch Tuesday

Any individual that has spent time on a personal computer knows what an update or patch is. A patch is a set of changes or updates done to a computer program or application — everything from the operating system (OS) to business apps and browsers. This is mostly done to fix a software bug or error or to provide new features and enhancements. Patching of software is important since security patches address software vulnerabilities that cybercriminals might exploit to gain unauthorized access to your device and your data.

What Is Patch Tuesday?

Microsoft Patch Tuesday is the second Tuesday of every month on which Microsoft releases security-related updates for its Windows OS, browsers and business applications. The other updates, not related to security, are released on the fourth Tuesday of every month. Sometimes, Microsoft releases an out-of-band (OOB) update for an emergency security issue that is not published specifically on the second Tuesday, but could be published on any day of the month.

When Did Patch Tuesday Begin?

Patch Tuesday was introduced by Microsoft in October 2003 to mainly reduce the cost of distributing patches. Tuesday was specifically chosen as the optimal day of the week so as to allow users to apply patches over the week. Monday was left free to address any issues that arose over the preceding weekend.

Severity Rating System for Vulnerabilities

To help customers understand the importance of applying a particular patch, Microsoft has published a severity rating system that rates each vulnerability according to the worst theoretical outcome should that vulnerability be exploited.

RatingDescription
CriticalIt is recommended that critical updates are applied quickly. A vulnerability is rated critical when its exploitation could allow code execution without user interaction.
ImportantA vulnerability that could result in the compromise of confidentiality and integrity of user data. Microsoft recommends that customers apply important updates at the earliest opportunity.
ModerateA vulnerability that is mitigated to a significant degree by certain factors such as default configuration, auditing and authentication requirements. Microsoft recommends that customers consider applying the security update.
LowA vulnerability that is extremely difficult to exploit or has minimal impact.

Why is Patching Needed?

Patching is required to remediate software vulnerabilities that can be exploited by hackers. It helps prevent security breaches, data theft, data loss and violation of compliance regulations. Timely deployment of patches is a critical part of a business’ IT security strategy.

How do I check my Edition, Version and OS Build on Windows 10?

Login to your computer and select the start button. 

Go to Settings > System > About

Open the About settings. Depending on the version of Windows 10 you have, you can see System Type (32-bit or 64-bit), Edition, Version and OS Build on the same page (see screenshot below) or under Device specifications > System type and Windows specifications.

How can users check which patches they have gotten?

If the user is using a Windows-based personal computer:

Click on Search>Windows Update Settings> View update history. Here you can see the versions of the software installed on your computer. If you’d like to check for any missing updates, click on “Check for updates.”

Are Microsoft patches cumulative?

Patch Tuesday updates, which are Windows security updates are cumulative and are released on the second Tuesday of each month. Cumulative updates mean if you miss an update one month, it’s rolled into the patch for the next month.

What is the difference between a patch and an update?

General software updates are feature based updates, to enhance the functionality of the software, while Patch Tuesday patches are specifically for security fixes.

Are updates only released on Patch Tuesday?

No. Feature updates that improve the capabilities or functionalities of a software are released twice a year, during spring and fall, also known as “semi-annual” releases. 

Windows security improvements are released on “Patch Tuesday” meaning on the second Tuesday of each month.

Occasionally, when there is a high-risk security vulnerability discovered, Microsoft releases an out-of-band patch, in between Patch Tuesdays, that should be applied immediately. 

What is Exploit Wednesday?

The day following the release of the security updates on Patch Tuesday is called the Exploit Wednesday, as hackers become more active on these days, preying on unpatched vulnerabilities. Hence, it is recommended to install a patch as soon as possible to reduce the risk of security breaches.


Patch Tuesday: March 2021 Updates

This month’s Patch Tuesday security updates are here. In the March release, Microsoft has rolled out 82 security patches for Windows and other supported software. 10 out of these patches are deemed “Critical” in severity. The Internet Explorer vulnerability CVE-2021-26411 has seen active exploitation. An attacker could host a specially crafted website designed to exploit the vulnerability through Internet Explorer and then convince a user to view the website.  Below are the details of the critical patches.

IDTitleRating
 CVE-2021-21300 Git for Visual Studio Remote Code Execution Vulnerability Critical
CVE-2021-24089 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2021-26411 Internet Explorer Memory Corruption Vulnerability Critical
CVE-2021-26867 Windows Hyper-V Remote Code Execution Vulnerability Critical
CVE-2021-26876 OpenType Font Parsing Remote Code Execution Vulnerability Critical
CVE-2021-26897 Windows DNS Server Remote Code Execution Vulnerability Critical
CVE-2021-26902 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2021-27061 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2021-27074 Azure Sphere Unsigned Code Execution Vulnerability Critical
CVE-2021-27080 Azure Sphere Unsigned Code Execution Vulnerability Critical

Here are the release notes for the March 2021 security updates. 


Patch Tuesday: February 2021 Updates

Patch Tuesday is here. In this February 2021 release, Microsoft rolled out updates for 56 security vulnerabilities across Windows OS, Windows Server, Windows Defender, Windows PowerShell, Azure, Microsoft Edge and more. 

11 of these 56 updates are deemed to be “critical”, and allow remote code execution, meaning these require special attention and should be patched as soon as possible. 

The updates included a “zero-day” vulnerability CVE-2021-1732, an elevation of privilege bug that affects Windows Server 2019, Windows Server 20H2 and Windows 10. This “important” vulnerability has already been exploited in the wild.

As noted in Krebs on Security, there are two critical vulnerabilities in Microsoft’s .NET Framework that are a concern because .NET is “a component required by many third-party applications (most Windows users will have some version of .NET installed).”

Further, Krebs says, “Windows 10 users should note that while the operating system installs all monthly patch roll-ups in one go, that rollup does not typically include .NET updates, which are installed on their own. So when you’ve backed up your system and installed this month’s patches, you may want to check Windows Update again to see if there are any .NET updates pending.”

CVE-2021-24078 is a Windows DNS Server Remote Code Execution Vulnerability that has a CVSS score of 9.8, which is extremely high. According to Kev Breen of Immersive Labs, this vulnerability could be exploited to let an attacker “steal a lot of data by essentially altering the destination for organizational traffic; for example, by pointing internal appliances or Outlook Web Access at a malicious server.”

The details of the critical vulnerabilities are as below: 

IDTitleRating
CVE-2021-1722 Windows Fax Service Remote Code Execution VulnerabilityCritical
CVE-2021-24074 Windows TCP/IP Remote Code Execution VulnerabilityCritical
CVE-2021-24077 Windows Fax Service Remote Code Execution VulnerabilityCritical
CVE-2021-24078 Windows DNS Server Remote Code Execution VulnerabilityCritical
CVE-2021-24081 Microsoft Windows Codecs Library Remote Code Execution VulnerabilityCritical
CVE-2021-24088 Windows Local Spooler Remote Code Execution VulnerabilityCritical
CVE-2021-24091 Windows Camera Codec Pack Remote Code Execution VulnerabilityCritical
CVE-2021-24093 Windows Graphics Component Remote Code Execution VulnerabilityCritical
CVE-2021-24094Windows TCP/IP Remote Code Execution VulnerabilityCritical
CVE-2021-24112 .NET Core Remote Code Execution VulnerabilityCritical
CVE-2021-26701.NET Core Remote Code Execution VulnerabilityCritical

Here are the release notes for the February 2021 security updates. 


Patch Tuesday: January 2021 Updates

The first Patch Tuesday of the year is here. In this January 2021 release, Microsoft rolled out updates for 83 security vulnerabilities across Windows OS, Windows Server, Windows Defender, Azure, Microsoft Edge and more.

Nine of these 83 updates are deemed to be “critical”, and allow remote code execution, meaning these require special attention and should be patched as soon as possible.

One of the most critical vulnerabilities is the Microsoft Defender Remote Code Execution Vulnerability – CVE-2021-1647 – a zero-day vulnerability that is known to be actively exploited. Typically, the Microsoft Malware Protection Engine will be updated automatically. As discussed in the Microsoft Update Guide, “best practices recommend that customers regularly verify whether software distribution, such as the automatic deployment of Microsoft Malware Protection Engine updates and malware definitions, is working as expected in their environment.”

The details of the critical vulnerabilities are as below:

IDTitleRating
CVE-2021-1643HEVC Video Extensions Remote Code Execution VulnerabilityCritical
CVE-2021-1647Microsoft Defender Remote Code Execution VulnerabilityCritical
CVE-2021-1658Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-1660Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-1665GDI+ Remote Code Execution VulnerabilityCritical
CVE-2021-1666Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-1667Remote Procedure Call Runtime Remote Code Execution VulnerabilityCritical
CVE-2021-1668Microsoft DTV-DVD Video Decoder Remote Code Execution VulnerabilityCritical
CVE-021-1673Microsoft DTV-DVD Video Decoder Remote Code Execution VulnerabilityCritical

Here are the release notes for the January 2021 security updates.


Patch Tuesday: December 2020 Updates

The second Tuesday of the month has arrived. We all know what that means. We are back today with the Microsoft Patch Tuesday updates for December 2020.

This month, Microsoft has fixed 58 vulnerabilities of which 22 are classified as remote code execution (RCE) vulnerabilities. These RCE vulnerabilities are the ones that should be addressed as soon as possible since they could be exploited via the internet without user interaction. Pay particular attention to the RCE bugs that affect Microsoft Exchange, SharePoint and Hyper-V.

When it comes to severity, 9 of the vulnerabilities are “Critical” affecting Microsoft Exchange Server (2013, 2016, 2019), Microsoft SharePoint, Dynamics 365 for Finance and Operations, Windows Server (2016 and 2019), Windows 10, ChakraCore and Microsoft Edge.

48 of the vulnerabilities are classified as “Important” and two others as “Moderate”. The December Patch Tuesday patches do not remediate any zero-day vulnerabilities. The CVE details for the critical vulnerabilities are listed below:

IDTitleRating
CVE-2020-17095Hyper-V Remote Code Execution VulnerabilityCritical
CVE-2020-17117  Microsoft Exchange Remote Code Execution VulnerabilityCritical
CVE-2020-17118 Microsoft SharePoint Remote Code Execution Vulnerability Critical
CVE-2020-17121 Microsoft SharePoint Remote Code Execution VulnerabilityCritical
CVE-2020-17131 Chakra Scripting Engine Memory Corruption Vulnerability Critical
CVE-2020-17132 Microsoft Exchange Remote Code Execution Vulnerability Critical
CVE-2020-17142 Microsoft Exchange Remote Code Execution Vulnerability Critical
CVE-2020-17152 Microsoft Dynamics 365 for Finance and Operations (on-premises) Remote Code Execution VulnerabilityCritical
CVE-2020-17158 Microsoft Dynamics 365 for Finance and Operations (on-premises) Remote Code Execution Vulnerability   Critical

Here are the release notes for the December 2020 security updates.


Patch Tuesday: November 2020 Updates

On Tuesday, November 10, 2020, Microsoft released its monthly set of software security patches. This month, they have remediated 112 software vulnerabilities. Among these, Microsoft provided a patch for a zero-day vulnerability, CVE-2020-17087, Windows Kernel Local Elevation of Privilege Vulnerability, which has already been exploited “in the wild.”  The exploit works in conjunction with a Google Chrome zero-day vulnerability, as described in this ZDNet article.

The Chrome zero-day vulnerability has been patched in Chrome version 86.0.4240.111. The Windows vulnerability affects all currently supported versions of Windows, including Windows 10 and Windows Server.

Out of the 112 vulnerabilities, there are 24 that can allow remote code execution (RCE) exploits in a number of different Microsoft products, and 17 are rated “critical,” impacting the following:

  • Windows Server, Version 20H2 (Server Core Installation)
  • Raw Image Extension
  • Microsoft Edge (EdgeHTML-based)
  • Internet Explorer 11
  • HEVC Video Extensions
  • HEIF Image Extension
  • Azure Sphere and
  • AV1 Video Extension

The CVE details of the critical vulnerabilities are listed below:

IDTitleRating
CVE-2020-16988 Azure Sphere Elevation of Privilege VulnerabilityCritical
CVE-2020-17042 Windows Print Spooler Remote Code Execution Vulnerability Critical
CVE-2020-17048Chakra Scripting Engine Memory Corruption Vulnerability Critical
CVE-2020-17051 Windows Network File System Remote Code Execution VulnerabilityCritical
CVE-2020-17052 Scripting Engine Memory Corruption Vulnerability Critical
CVE-2020-17053 Internet Explorer Memory Corruption Vulnerability Critical
CVE-2020-17058 Microsoft Browser Memory Corruption Vulnerability Critical
CVE-2020-17078Raw Image Extension Remote Code Execution VulnerabilityCritical
CVE-2020-17079 Raw Image Extension Remote Code Execution Vulnerability  Critical
CVE-2020-17082 Raw Image Extension Remote Code Execution Vulnerability Critical
CVE-2020-17101 HEIF Image Extensions Remote Code Execution Vulnerability Critical
CVE-2020-17105 AV1 Video Extension Remote Code Execution Vulnerability Critical
CVE-2020-17106 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2020-17107 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2020-17108HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2020-17109 HEVC Video Extensions Remote Code Execution Vulnerability Critical
CVE-2020-17110 HEVC Video Extensions Remote Code Execution Vulnerability Critical

Here are the release notes for the November 2020 security updates.


Patch Tuesday: October 2020 Updates

Microsoft provides Patch Tuesday updates in its Security Update Guide portal. Each update also comes with a set of release notes. (See this month’s release notes at the bottom of this blog.)

The Common Vulnerabilities and Exposure (CVE) ID is a format in which each vulnerability is disclosed and cataloged in the National Vulnerability Database (NVD). Vulnerabilities in the NVD have a criticality rating ranging from 1 (lowest) to 10 (highest).

For the October 2020 Patch Tuesday, a total of 87 CVEs were released, with 11 of them rated “Critical.” The October security updates are for the following Microsoft software:

  • Microsoft Windows
  • Microsoft Office and Microsoft Office Services and Web Apps
  • Microsoft JET Database Engine
  • Azure Functions
  • Open Source Software
  • Microsoft Exchange Server
  • Visual Studio
  • PowerShellGet
  • Microsoft .NET Framework
  • Microsoft Dynamics
  • Adobe Flash Player
  • Microsoft Windows Codecs Library

Below are the CVE details of the “Critical” vulnerabilities in this month’s update.

IDTitleRatingDescription
CVE-2020-16891Windows Hyper-V Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists when Windows Hyper-V on a host server fails to properly validate input from an authenticated user on a guest operating system.
CVE-2020-16898Windows TCP/IP Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists when the Windows TCP/IP stack improperly handles ICMPv6 Router Advertisement packets.
CVE-2020-16911GDI+ Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists in the way that the Windows Graphics Device Interface (GDI) handles objects in memory.
CVE-2020-16915Media Foundation Memory Corruption VulnerabilityCriticalA memory corruption vulnerability exists when Windows Media Foundation improperly handles objects in memory.
CVE-2020-16923Microsoft Graphics Components Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists in the way that Microsoft Graphics Components handle objects in memory.
CVE-2020-16947Microsoft Outlook Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists in Microsoft Outlook software when the software fails to properly handle objects in memory.
CVE-2020-16951Microsoft SharePoint Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package.
CVE-2020-16952Microsoft SharePoint Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package.
CVE-2020-16967Windows Camera Codec Pack Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists when the Windows Camera Codec Pack improperly handles objects in memory.
CVE-2020-16968Windows Camera Codec Pack Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists when the Windows Camera Codec Pack improperly handles objects in memory.
CVE-2020-17003Base3D Remote Code Execution VulnerabilityCriticalA remote code execution vulnerability exists when the Base3D rendering engine improperly handles memory.

The complete details of all 87 October 2020 security updates can be found on the Microsoft’s Security Update Guide page. The release notes can be found here as well.

We highly recommend that you apply these patches at the earliest, within 30 days of release at the latest.

Learn more about patching in Kaseya VSA here.

The post Patch Tuesday: April 2021 appeared first on Kaseya.


*** This is a Security Bloggers Network syndicated blog from Blog – Kaseya authored by John Emmitt. Read the original post at: https://www.kaseya.com/blog/2020/10/14/patch-tuesday/