DCOM Issue after installing Windows Patch KB5004238

Question

I currently have a custom application that's attempting to pull OPC data from a Windows 2016 server. Prior to updating my server with the patch, the application was able to collect data from the OPC server on the 2016 server. However, after updating the Windows 2016 server with the KB5004238 patch, the application was unable to pull the OPC data anymore. If I remove the patch, then I'm able to pull data again. However, I know that it comes with many improvements to Windows security.

Does anyone know what DCOM settings were changed with the KB5004238 patch? That would make it easier for me to troubleshoot my code and make changes to either the server or code to allow the application to pull data with the patch.

Answer 1

Whos' OPC server are you using? The vendor will likely be aware this and also if there's a fix in the works.

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Answer 2

@Anonymous : at least from what I'm seeing, we're seeing issue communicating to SoftwareToolBox's Topserver/Kepware. However, I've tried other industry OPC servers, and it seems to be any OPC server

Answer 3

Looks like you're not alone in this.
https://learn.microsoft.com/en-us/answers/questions/484076/problem-with-dcom-connections-after-windows-server.html

I signed in to my RockwellAutomation account and did a quick search but got no hits in KB or forums there. Probably the issue is too new.

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Answer 4

Hi

Then what about installing the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU)?
SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes.

Lastest Servicing Stack Updates
https://msrc.microsoft.com/update-guide/en-us/vulnerability/ADV990001

This website lists all July 2021 Security Updates:
https://msrc.microsoft.com/update-guide/releaseNote/2021-Jul
If the problem still consists,
we could also share thoughts or send an email to msrc_eng_support@microsoft.com

Hope these information could bring you some help.
Best Regards

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