This blog has been updated to include the details of the zero-day vulnerabilities that were not marked initially by Microsoft.

Details of the zero-days

Vulnerable component: Proxy Driver

Impact: Spoofing

CVSS 3.1: 6.7

Microsoft has stated that this vulnerability is being actively exploited and publicly disclosed. However, this has been rated as Important by the vendor. 

Vulnerable component: SmartScreen Prompt

Impact: Security Feature Bypass

CVSS 3.1: 8.8

While Microsoft has stated that the vulnerability has not yet been actively exploited or publicly disclosed, “To exploit this security feature bypass vulnerability, an attacker would need to convince a user to launch malicious files using a launcher application that requests that no UI be shown.”

April Patch Tuesday

Welcome to the Patch Tuesday update for April 2024, which lists fixes for 149 vulnerabilities. Two zero-days have been listed by Microsoft this month along with three critical vulnerabilities.

After an initial discussion about this month’s updates, we’ll offer our advice for devising a plan to handle patch management in a hybrid work environment. You can also register for our free Patch Tuesday webinar and listen to our experts break down Patch Tuesday updates in detail.  

What is Patch Tuesday?   

Patch Tuesday falls on the second Tuesday of every month. On this day, Microsoft releases security and non-security updates for its operating system and other related applications. Since Microsoft has upheld this process of releasing updates in a periodic manner, IT admins expect these updates and have time to gear up for them.

Why is Patch Tuesday important?   

Important security updates and patches to fix critical bugs or vulnerabilities are released on Patch Tuesday. Usually, zero-day vulnerabilities are also fixed during Patch Tuesday unless the vulnerability is critical and highly exploited, in which case an out-of-band security update is released to address that particular vulnerability.

April 2024 Patch Tuesday   

Security updates lineup  

Here is a breakdown of the vulnerabilities fixed this month:

  • CVE IDs: 149 (this count doesn’t include the republished CVE IDs)
  • Republished CVE IDs: Six (more details on this below)

Here is a breakdown of the 149 vulnerabilities fixed this month, based on severity:

  • Critical: 3
  • Important: 146

Security updates were released for the following products, features, and roles 

  • Windows BitLocker
  • Microsoft Office Outlook
  • Windows Remote Procedure Call
  • Azure Private 5G Core
  • .NET and Visual Studio
  • Azure Compute Gallery
  • Microsoft Install Service
  • Windows DWM Core Library
  • Azure Migrate
  • Windows Local Security Authority Subsystem Service (LSASS)
  • Microsoft WDAC ODBC Driver
  • Windows File Server Resource Management Service
  • Windows HTTP.sys
  • Windows Mobile Hotspot
  • Windows Proxy Driver
  • Windows Defender Credential Guard
  • Windows Win32K – ICOMP
  • Windows Telephony Server
  • Windows USB Print Driver
  • Microsoft Office SharePoint
  • Windows Virtual Machine Bus
  • Windows Compressed Folder
  • Microsoft Office Excel
  • Azure Arc
  • Windows Storage
  • Azure AI Search
  • Role: Windows Hyper-V
  • Internet Shortcut Files
  • Azure Monitor
  • Microsoft Azure Kubernetes Service
  • Azure SDK
  • Azure

Learn more in the MSRC’s release notes.

 The critical vulnerabilities   

Vulnerable component: Microsoft Defender for IoT  

Impact: Remote Code Execution

CVSS 3.1: 8.8

While this vulnerability is not actively exploited yet, Microsoft states that, “An authenticated attacker with access to the file upload feature could exploit this path traversal vulnerability by uploading malicious files to sensitive locations on the server.”

Vulnerable component: Microsoft Defender for IoT

Impact: Remote Code Execution

CVSS 3.1: 8.8

This path traversal vulnerability in Microsoft Defender for IoT requires the attacker to send a malicious update package to the Defender for IoT sensor over the network. For a successful exploitation, the attacker is required to gain the necessary permissions by authenticating themselves.

Vulnerable component: Microsoft Defender for IoT

Impact: Remote Code Execution

Tracked as CWE-77, such vulnerability usually occur when the user-provided inputs are directly used in system commands before properly sanitizing them. Microsoft has stated that this vulnerability is less likely to be exploited and that a successful exploitation requires the attacker to be an administrator of the web application.

Republished CVE IDs   

Besides the vulnerabilities fixed in this month’s Patch Tuesday, Microsoft has also republished six CVE IDs. These are as follows:

Third-party updates released after last month’s Patch Tuesday   

Third-party vendors such as Google, Cisco, D-Link, and SAP have also released updates this April.

Best practices to handle patch management in a hybrid work environment   

Most organizations have opted to embrace remote work even after they have been cleared to return to the office. This decision poses various challenges to IT admins, especially in terms of managing and securing distributed endpoints.

Here are a few pointers to simplify the process of remote patching:

  • Disable automatic updates because one faulty patch could bring down the whole system. IT admins can educate end users on how to disable automatic updates on their machines. Patch Manager Plus and Endpoint Central also have a dedicated patch, 105427, that can be deployed to endpoints to ensure that automatic updates are disabled.
  • Create a restore point—a backup or image that captures the state of the machines—before deploying big updates like those from Patch Tuesday.
  • Establish a patching schedule and keep end users informed about it. It is recommended to set up a time for deploying patches and rebooting systems. Let end users know what needs to be done on their end for trouble-free patching.
  • Test the patches on a pilot group of systems before deploying them to the production environment. This will ensure that the patches do not interfere with the workings of other applications.
  • Since many users are working from home, they all might be working different hours; in this case, you can allow end users to skip deployment and scheduled reboots. This will give them the liberty to install updates at their convenience and avoid disrupting their work. Our patch management products come with options for user-defined deployment and reboot.
  • Most organizations are deploying patches using a VPN. To stop patch tasks from eating up your VPN bandwidth, install Critical patches and security updates first. You might want to hold off on deploying feature packs and cumulative updates since they are bulky updates and consume a lot of bandwidth.
  • Schedule the non-security updates and security updates that are not rated Critical to be deployed after Patch Tuesday, such as during the third or fourth week of the month. You can also choose to decline certain updates if you feel they are not required in your environment.
  • Run patch reports to get a detailed view of the health status of your endpoints.
  • For machines belonging to users returning to the office after working remotely, check if they are compliant with your security policies. If not, quarantine them. Install the latest updates and feature packs before deeming your back-to-office machines fit for production. Take inventory of and remove apps that are now obsolete for your back-to-office machines, like remote collaboration software.

With Endpoint Central, Patch Manager Plus, or Vulnerability Manager Plus you can completely automate the entire process of patch management, from testing patches to deploying them. You can also tailor patch tasks according to your current needs. For a hands-on experience with either of these products, try a free, 30-day trial and keep thousands of applications patched and secure.

Want to learn more about Patch Tuesday updates? Join our experts as they break down this month’s Patch Tuesday updates and offer in-depth analysis. You can also ask our experts questions and get answers to all your Patch Tuesday questions. Register for our free Patch Tuesday webinar.

Ready, get set, patch!