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Software Toolbox OPC Test Client and DCOM Hardening (CVE-2021-26414, KB5004442)

This FAQ discusses how the Software Toolbox OPC Test Client, the OPC DA test client that installs with OmniServer or is available as a standalone installation, is affected by the changes made by Windows updates that are described in Microsoft's KB50004442 advisory regarding Windows Updates that have been rolled out to affected operating systems by Microsoft since June 8, 2021 to address vulnerabilities in DCOM described in CVE-2021-26414.  Due to upcoming enforcement actions by Microsoft, users may need to take actions described in this FAQ. This FAQ is a supplement to our overall detailed technical FAQ regarding DCOM Hardening which contains information that is common to all products affected by DCOM hardening. You may also request our free detailed Remote OPC DA Classic (DCOM) Configuration Guide here with recommendations for DCOM setting configuration on OPC DA client and server machines where connections will be remote (client and server on separate machines).

Specific Product Editions/Versions or Use Cases Affected and Not Affected

All versions of the Software Toolbox OPC Test Client that install with any version of OmniServer are affected for its OPC DA Client interface if you are connecting OmniServer or other OPC DA servers over a network. Many users will NOT be affected, as described below. 
Affected:
  • YOU MUST review this FAQ and determine what actions you choose to take if you are using the Software Toolbox OPC Test Client connecting to OmniServer (or other OPC DA servers) on a different computer than the Software Toolbox OPC Test Client, which means DCOM is being used.
Not Affected:
  • If you are only ever using the Software Toolbox OPC Test Client to interact with OmniServer (or other OPC DA servers) only on the SAME COMPUTER as the OPC DA server (i.e. it's a local connection), this FAQ does NOT apply to your application. However, it is still recommended that you review this FAQ in the event you have to introduce remote OPC DA Classic connections using the Software Toolbox OPC Test Client in the future.

General Relevant Product information

Is OPC UA available in this product as an alternative?  No, however most users only use the Software Toolbox OPC Test Client on the same computer as OmniServer, and thus are not affected.
Operating System Support Details - Software Toolbox OPC Test Client is supported on the same operating systems as OmniServer - see list of supported operating systems for OmniServer
Respects Component Services Settings? Yes.
Uses Hard-Coded Co-Initialize security Calls? No.
DCOM Hardening Specific Updates Relevant and Available? None required, however we always recommend running the most current version of the product (i.e. either the latest version of OmniServer since the Software Toolbox OPC Test Client installs with OmniServer or the latest standalone installer) and reserve the right to limit support for non-current software. 
Obtaining Current Product Versions Users on active support & maintenance agreements are entitled to update at no additional cost. Current OmniServer version including the latest version of Software Toolbox OPC Test Client is available on the OmniServer website. Contact us with your OmniServer license details to check your support status and, if necessary, obtain quote for reinstatement of support & maintenance. For users of the standalone Software Toolbox OPC Test Client, you can request the current version here.
 
After March 14, 2023, because you will no longer be able to disable the changes described in the KB50004442 advisory with a registry entry, you must have prepared any affected systems requiring changes by adjusting your computers' global DCOM Authentication Level setting to use the Packet Integrity option (per the screenshot below), migrated to OPC UA, or implemented another DCOM alternative.  For general DCOM configuration recommendations beyond the required DCOM Authentication Level (which is beyond the scope of this FAQ), consult our DCOM Tutorial; HOWEVER, the recommendations found here regarding Authentication Level OVERRIDE/SUPERSEDE anything in our DCOM tutorial. You may also request our free detailed Remote OPC DA Classic (DCOM) Configuration Guide here with recommendations for DCOM setting configuration on OPC DA client and server machines where connections will be remote (client and server on separate machines).
Default_DCOM_Authentication_Level

What About Other Vendors' OPC Classic Servers Being Used with Software Toolbox OPC Test Client?

As covered in our DCOM Hardening FAQ, all OPC Classic client and server applications have two methods that may have been implemented with respect to handling DCOM Authentication Level. They can:
  1. Set DCOM security settings programmatically, or
  2. Allow their application to use settings in the Windows Component Services DCOM Config utility to determine the settings
Provided you have made the recommended changes above, the Software Toolbox OPC Test Client uses Method #2 for DCOM connections, which means the Software Toolbox OPC Test Client itself requires no updates or patches to its code to address these DCOM changes. That being said, the Software Toolbox OPC Test Client is just one component of the client/server model in any of your systems using the Software Toolbox OPC Test Client.
 
For your OPC DA Classic server applications being used with the Software Toolbox OPC Test Client, you will need to consult with that server application vendor to confirm which method they are using for DCOM security settings.
For OPC DA Classic Server Vendors Using Method #1, that vendor will either have to provide a version of their software that allows the DCOM Authentication Level to be configured in the software or a version where the hard-coded DCOM Authentication Level is Packet Integrity level.
For OPC Classic Server Vendors Using Method #2 (just like the Software Toolbox OPC Test Client and OmniServer are), making the previously indicated adjustment of the computers' global DCOM Authentication Level to Packet Integrity should be all that is required (this change needs to be performed on both the OPC Classic client and server machines).
 
If you're unsure which method your other OPC DA Classic server software vendors are using, ask them how they are addressing Microsoft's DCOM hardening changes as they apply to their OPC Classic solutions.

Considerations Regarding Alternatives to DCOM

DCOM has been a challenge for users making remote OPC Classic connections for many years, due to the subtle nuances of DCOM operation between different Windows operating systems and different network architectures. As such, there are several alternatives available for users that prefer to migrate away from DCOM entirely ahead of these DCOM hardening changes as a method for future-proofing remote connections from any further Microsoft changes to DCOM security.
  1. Simply migrate all OPC Classic client and server applications to reside on the same computer (resulting in local only OPC Classic connections that are not susceptible to DCOM security changes).
  2. Migrate from OPC Classic to OPC UA wherever possible for remote connections. One of the key benefits of OPC UA is increased security without the pitfalls of DCOM for remote connections. While this won't address remote DCOM concerns for the Software Toolbox OPC Test Client that is a DA only free test client, there are OPC UA test client applications available (such as the UaExpert client from Unified Automation - free log-in required). To learn more about OPC UA, click here.
  3. If you are using the Software Toolbox OPC Test Client that with another OPC server that uses OPC UA, you could put the DataHub OPC Gateway on the machine with our test client.  The test client would connect to the gateway as a local OPC DA server, and then the gateway communicates via OPC UA to the servers. Contact us for details, or download the DataHub free trial.
  4. Alternatively, you can use the DataHub Tunneler to replace DCOM. 
Disclaimer: You are ultimately responsible to work with your IT/OT teams on handling the changes to your systems. Software Toolbox support cannot and will not make changes to customer systems for them. This information is provided for reference and is based on our best commercially reasonable efforts to gather, validate and aggregate this knowledge and is provided under and subject to our standard terms and conditions.