KB5033420 Monthly Rollup Update for Windows Server 2012 R2

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KB5033420 is the cumulative monthly rollup update for Windows Server 2012 R2. It was released on 12 December 2023 under the ‘Patch Tuesday’ program of Microsoft.

Windows Server 2012 R2 reached ‘End of Support’ on 10 October 2023. Going forward, ESU or Extended Security Updates will be available for Windows Server 2012 R2.

ESU or Extended Security Updates are cumulative. You can buy ESU for Windows Server 2012 R2 on an annual renewal basis until October 2026.

Salient points

  • KB5033420 has been superseded by KB5034171. You can read about it on the KB5034171 page.
  • KB5033420 is the monthly rollup update (ESU or Extended Security Update) for Windows Server 2012 R2 and supersedes the KB5032249 update.
  • KB5032249 was released on 14 November 2023. You can read more about it on the KB5032249 page.
  • KB5032308 is the Servicing Stack Update that corresponds to KB5032249 and KB5033420. The SSU was released on 14 November 2023. You would need to deploy KB5032308 before installing the KB5033420 monthly rollup update.
  • If you installed KB5032249, the Servicing Stack Update KB5032308 would have been already installed.
  • No new SSU for Windows Server 2012 R2 has been released in December 2023.
  • 18 security vulnerabilities affect Windows Server 2012 R2 as part of the December 2023 security report.
  • Three CRITICAL security vulnerabilities affect Windows Server 2012 R2. You can read more about this vulnerability in the vulnerabilities section.
  • CVE-2023-20588 is a zero-day threat affecting AMD servers. Windows 2012 R2 servers are affected by this zero-day threat.
  • The issue with language packs continues to affect Windows Server 2012 R2. If you install a language pack after installing KB5033420, you will need to re-install the KB5033420 update. This is because installing a language pack renders the monthly rollup update infructitious.

To install KB5033420, you will need a valid key for the Extended Security Updates because the Windows Server 2012 R2 attained End of Support status on 10 October 2023.

For Windows Server 2012 R2, you need to follow the 4-step process to avail of the Extended Security Update KB503420.

  1. Ensure that the Servicing Stack Update KB5029368 is installed on Windows Server 2012 R2. This SSU was released in August 2023. This SSU needs to be installed before you install the ESU preparation package.
  2. Buy the ESU license or Extended Security Update program subscription for one year. Download and install the ESU or Extended Security Update preparation package.
  3. Download and install the KB5032308 Servicing Stack update for Windows Server 2012 R2.
  4. Download and install the KB5033420 monthly rollup update.

If you installed KB5032249 in November 2023, you can skip steps 1 to 3. You can go directly to install the KB5033420 cumulative update.

Download KB5033420

KB5033420 is a cumulative monthly rollup update of the type of an Extended Security Update. It can be installed automatically or through a manual approach.

For automatic patching of the monthly rollup update, you could use one of the following methods:

  • Windows Update
  • WSUS or Windows Server Update Service

WSUS remains the best method to automatically import and deploy security updates or cumulative updates on Windows Servers. We strongly suggest using WSUS as the preferred method for rolling out updates.

However, you will still need a valid key to apply the Extended Security Updates on Windows Server 2012 R2.

For manual installation, you can download the offline installer files from the Microsoft Update Catalog site. Alternatively, you can use the direct download links for KB5033420 shared below.

The manual installation of KB5033420 involves the following 4 steps:

  1. Download and install KB5029368 Servicing Stack Update
  2. Download and install ESU package KB5017220 for Windows Server 2012
  3. Download and install Servicing Stack Update KB5032308
  4. Download and install the KB5033420 cumulative update

If you have already availed the ESU or Extended Security Update licensing, you may have already deployed KB5029368 and KB5017220.

If you did install KB5032249 in November 2023, you would have already deployed the SSU KB5032308. In such a case, you just need to install the latest KB5033420 monthly rollup update.

For each of these updates, we have shared the download links below.

Download KB5029368

The Servicing Stack Update file for KB5029368 has a size of 10.5 MB. Servicing Stack Updates, upon installation, do not cause the server to reboot. This Servicing Stack Update was released in August 2023.

This Servicing Stack Update is required before installing the ESU preparation package on Windows Server 2012 R2.

KB5017220 is the ESU or Extended Security Update preparation package. Before you can deploy an Extended Security Update, you need to install this package on Windows Server 2012 R2.

You can download the package from the Microsoft Update Catalog site or from the direct download link shared below.

The size of the preparation package is 424 KB only. This package will prepare your Windows Server 2012 R2 to accept the Extended Security Updates released under the ‘Patch Tuesday’ project.

KB5032308 is the latest Servicing Stack Update for Windows Server 2012 R2. It was released on 14 November 2023. You can download the SSU from the Catalog site or use the direct download link shared below.

SSU will not cause a server reboot.

The size of the Servicing Stack Update KB5032308 is 10.5 MB only.

Download KB5033420

The download links for KB5033420 are shared hereunder.

The size of the offline installer file for KB5033420 is 586.1 MB.

The server will reboot post-installation of the monthly rollup update. So, we do suggest installing the cumulative update as part of an organized change process within the IT infrastructure.

Vulnerabilities

There are 18 security vulnerabilities that have been disclosed for Windows Server 2012 R2 as part of the December 2023 security bulletin released by Microsoft.

We have listed the three CRITICAL threats and a single zero-day threat that affects Windows Server 2012 R2 below.

The zero-day vulnerabilities are publicly known and exploited vulnerabilities. Therefore, immediate patching needs to be carried out to mitigate the risk arising out of zero-day vulnerabilities within the IT infrastructure.

The following zero-day threat was first reported in August 2023. It has been mitigated in the current Windows Update cycle. Therefore, we suggest immediate deployment of the cumulative update KB5033420 for Windows Server 2012 R2.

CVE detailsCVSSSeverityImpact Description
CVE-2023-205885.5IMPORTANTInformation DisclosureA division-by-zero error on some AMD processors can potentially return speculative data resulting in loss of confidentiality.

CRITICAL vulnerabilities

3 CRITICAL security vulnerabilities affect Windows Server 2012 R2. All these threats have ‘Remote Code Execution’ impact.

CVE detailsCVSSSeverityImpact Description
CVE-2023-356308.8CRITICALRemote Code ExecutionThis threat impacts the Internet Connection Sharing (ICS).

Successful exploitation of this vulnerability requires the attacker to modify an option->length field in a DHCPv6 DHCPV6_MESSAGE_INFORMATION_REQUEST input message.
This attack is limited to systems connected to the same network segment as the attacker. 
CVE-2023-356288.1CRITICALRemote Code ExecutionThis vulnerability arises on account of Windows MSHTML Platform.

The attacker could exploit this vulnerability by sending a specially crafted email which triggers automatically when it is retrieved and processed by the Outlook client. This could lead to exploitation BEFORE the email is viewed in the Preview Pane.

This could result in the attacker executing remote code on the victim’s machine.
CVE-2023-356418.8CRITICALRemote Code ExecutionThis threat affects the Internet Connection Sharing (ICS).

To exploit this vulnerability, an attacker would need to send a maliciously crafted DHCP message to a server that runs the Internet Connection Sharing service.

This attack is limited to systems connected to the same network segment as the attacker

The following changes are part of the KB5033420 monthly rollup update (Extended Security Updates) for Windows Server 2012 R2.

  • This update contains miscellaneous security improvements to internal Windows OS functionality.
  • This update brings in security changes for Windows Server 2012 R2.
Rajesh Dhawan

Rajesh Dhawan is a technology professional who loves to blog about smart wearables, Cloud computing and Microsoft technologies. He loves to break complex problems into manageable chunks of meaningful information.