{"id":59489,"date":"2025-09-26T10:48:16","date_gmt":"2025-09-26T10:48:16","guid":{"rendered":"https:\/\/becolve.com\/blog\/microsoft-dcom-patches-break-opc-da-communications-2\/"},"modified":"2025-09-26T10:48:16","modified_gmt":"2025-09-26T10:48:16","slug":"microsoft-dcom-patches-break-opc-da-communications-2","status":"publish","type":"blog","link":"https:\/\/becolve.com\/en\/blog\/microsoft-dcom-patches-break-opc-da-communications-2\/","title":{"rendered":"Microsoft DCOM Patches \u201cBreak\u201d OPC DA Communications"},"content":{"rendered":"
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Microsoft’s June cumulative updates include a security patch<\/strong> to limit the exposure of CVE-2021-26414 with CVSS of 4.3<\/strong>, where a potential attacker could bypass the security options implemented in DCOM. The patch is KB5004442<\/strong>. <\/p>\n

As of June 2022, this patch increases the default security level<\/strong> required for DCOM communications<\/strong>. As a reminder, DCOM (Distributed Component Object Model)<\/strong> is a protocol used to expose the objects of an application to RPCs (Remote Procedure Calls), so that the different components of devices can communicate over the network. <\/p>\n

\"data<\/p>\n

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All applications that use the Windows API<\/strong> to establish DCOM connections between two devices are affected. An example: OPC-DA.<\/p>\n

Classic OPC-DA<\/strong> uses DCOM communications to pass information between devices. The application of this patch, as of June 14, 2022, impacts all OPC-DA communication, as clients and servers must use the same DCOM authentication level. <\/p>\n

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I<\/span> Solutions for OPC-DA communication <\/strong><\/h2>\n
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1. (Temporary until March 14, 2023) Disable the mitigation<\/strong> of the vulnerability implemented in KB5004442 by modifying the HKEY_LOCAL_MACHINE SOFTWAREMicrosoftOleAppCompat registry key.<\/p>\n

2. Configure<\/strong> the DCOM authentication level to \u201cPacket Integrity\u201d or higher, both on the OPC server and on all clients.<\/p>\n

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For servers, the change is made at the Application level<\/span><\/p>\n

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For clients, the change is made at the \u201cMy Computer\u201d level<\/h3>\n

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On KepserverEX-based servers\/clients, it must be configured to follow the DCOM configuration<\/h3>\n
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