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Distributed Component Object Model
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<h2 id="security-improvements">Security improvements</h2> <p>As part of the initiative that began at Microsoft as part of Secure Development Lifecycle to re-architect insecure code, DCOM saw some significant security-focused changes in Windows XP Service Pack 2.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p><p>In response to a security vulnerability reported by Tencent Security Xuanwu Lab in June 2021,<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> Microsoft released security updates for several versions of Windows and Windows Server, hardening access to DCOM.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p> <h2 id="alternative-versions-and-implementations">Alternative versions and implementations</h2> <p>COMsource is a Unix based implementation of DCOM, allowing interoperability between different platforms. Its source code is available, along with full and complete documentation, sufficient to use and also implement an interoperable version of DCOM. COMsource comes directly from the <a href="/facts/Windows_NT/EtccWvxQ">Windows NT</a> 4.0 source code, and includes the source code for a <a href="/facts/Windows_Registry/cH9RlHTp">Windows NT Registry Service</a>. <a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p><p>In 1995, Digital and <a href="/facts/Microsoft/nGIDDXdx">Microsoft</a> announced Affinity for OpenVMS (also known as NT Affinity) which was intended to allow OpenVMS to serve as the <a href="/facts/Persistence_layer/frF0o2q2">persistence layer</a> for Windows NT <a href="/facts/Client%25E2%2580%2593server_model/FSnf27C5">client-server applications</a>.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> As part of this initiative, an implementation of the Distributed Component Object Model (DCOM) was added to OpenVMS Alpha.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> In order to support DCOM, VMS was provided with implementations of the Windows Registry, <a href="/facts/NTLM/R6H8vAFL">NTLM</a> authentication, and a subset of <a href="/facts/Win32/RRw4RtTu">Win32</a> APIs needed to support COM.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> DCOM was first added to OpenVMS V7.2-1 for the Alpha.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> A similar implementation of DCOM was added to <a href="/facts/Digital_Unix/J4tMy7uA">Digital Unix</a> as part of the AllConnect program.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p><p>TangramCOM was a separate project from Wine, focusing on implementing DCOM on Linux-based smartphones.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/ActiveX/xJb7t7Eh">ActiveX</a></li> <li><a href="/facts/Dynamic_Data_Exchange/0Ar2hzjA">Dynamic Data Exchange</a> (DDE)</li> <li><a href="/facts/.NET_Remoting/62V12d3N">.NET Remoting</a></li> <li><a href="/facts/OLE_for_process_control/AvudB9cl">OLE for Process Control</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://tools.ietf.org/html/draft-brown-dcom-v1-spec-03">Distributed Component Object Model Protocol -- DCOM/1.0</a></li> <li><a href="http://opengroup.org/comsource">The Open Groups COMsource</a> <a href="https://web.archive.org/web/20200113034910/http://opengroup.org/comsource">Archived</a> 2020-01-13 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a></li> <li><a href="https://web.archive.org/web/20091213022641/http://tcom.andjoin.com/">TangramCOM</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"What is Distributed Component Object Model (DCOM)?". WhatIs.com. Retrieved 2022-08-03. <a href="https://www.techtarget.com/whatis/definition/DCOM-Distributed-Component-Object-Model" target="_blank">https://www.techtarget.com/whatis/definition/DCOM-Distributed-Component-Object-Model</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"DCE 1.1: Remote Procedure Call - Introduction to the RPC API". pubs.opengroup.org. Retrieved 2022-08-03. <a href="https://pubs.opengroup.org/onlinepubs/9629399/chap2.htm" target="_blank">https://pubs.opengroup.org/onlinepubs/9629399/chap2.htm</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Nowak, Filip; Qasim, Mohsin. "A Comparison of Distributed Object Technologies CORBA vs DCOM" (PDF). Archived (PDF) from the original on 2017-08-29. <a href="https://middlewares.files.wordpress.com/2008/04/dcom_corba.pdf" target="_blank">https://middlewares.files.wordpress.com/2008/04/dcom_corba.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Object Technology Jeff Sutherland: Web Services: Better than CORBA or DCOM?". Retrieved 2022-08-03. <a href="http://jeffsutherland.com/2003/10/web-services-better-than-corba-or-dcom.html" target="_blank">http://jeffsutherland.com/2003/10/web-services-better-than-corba-or-dcom.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>stevewhims (23 August 2019). "Remote Procedure Calls Using RPC over HTTP - Win32 apps". docs.microsoft.com. Retrieved 2022-08-03. <a href="https://docs.microsoft.com/en-us/windows/win32/rpc/remote-procedure-calls-using-rpc-over-http" target="_blank">https://docs.microsoft.com/en-us/windows/win32/rpc/remote-procedure-calls-using-rpc-over-http</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Press Release Announcing DCOM Beta <a href="https://news.microsoft.com/1996/09/18/microsoft-releases-beta-version-of-dcom-for-windows-95/#Microsoft" target="_blank">https://news.microsoft.com/1996/09/18/microsoft-releases-beta-version-of-dcom-for-windows-95/#Microsoft</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Distributed Component Object Model (DCOM) Remote Protocol" (PDF). Microsoft - Distributed Component Object Model (DCOM) Remote Protocol. June 25, 2021. Archived (PDF) from the original on 2021-05-09. Retrieved August 3, 2022. <a href="https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-DCOM/%5bMS-DCOM%5d.pdf" target="_blank">https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-DCOM/%5bMS-DCOM%5d.pdf</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>DCOM Security Enhancements <a href="https://technet.microsoft.com/en-us/library/bb457156.aspx#EIAA" target="_blank">https://technet.microsoft.com/en-us/library/bb457156.aspx#EIAA</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Security Update Guide - Microsoft Security Response Center". msrc.microsoft.com. Retrieved 2022-08-03. <a href="https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26414" target="_blank">https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26414</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"KB5004442—Manage changes for Windows DCOM Server Security Feature Bypass (CVE-2021-26414)". support.microsoft.com. Retrieved 2022-08-03. <a href="https://support.microsoft.com/en-us/topic/kb5004442-manage-changes-for-windows-dcom-server-security-feature-bypass-cve-2021-26414-f1400b52-c141-43d2-941e-37ed901c769c" target="_blank">https://support.microsoft.com/en-us/topic/kb5004442-manage-changes-for-windows-dcom-server-security-feature-bypass-cve-2021-26414-f1400b52-c141-43d2-941e-37ed901c769c</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"DataSheet COMsource for Solaris, Tru64 UNIX and other Platforms". DataSheet COMsource for Solaris, Tru64 UNIX and other Platforms. <a href="http://www.opengroup.org/comsource/datasheet.htm" target="_blank">http://www.opengroup.org/comsource/datasheet.htm</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"OpenVMS at 20 Nothing stops it" (PDF). Digital. October 1997. Archived (PDF) from the original on 2021-04-19. Retrieved 2021-02-12. <a href="https://h50146.www5.hpe.com/products/software/oe/openvms/history/vaxvms20/pdf/vmsbook.pdf" target="_blank">https://h50146.www5.hpe.com/products/software/oe/openvms/history/vaxvms20/pdf/vmsbook.pdf</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Gene Cronin, Terence P. Sherlock (2000). COM Beyond Microsoft: Designing and Implementing COM Servers on Compaq Platforms. Digital Press. ISBN 1555582265. <a href="1555582265" target="_blank">1555582265</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>"OpenVMS Connectivity Developer Guide". hpe.com. July 2000. Archived from the original on 2020-12-04. Retrieved 2021-01-01. <a href="https://web.archive.org/web/20201204205526/http://h30266.www3.hpe.com/odl/vax/opsys/vmsos73/vmsos73/6539/6539pro.html" target="_blank">https://web.archive.org/web/20201204205526/http://h30266.www3.hpe.com/odl/vax/opsys/vmsos73/vmsos73/6539/6539pro.html</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"OpenVMS Alpha V7.2-1 Release Notes". odl.sysworks.biz. January 1999. Retrieved 2021-01-01. <a href="http://odl.sysworks.biz/disk$vaxdocmar002/opsys/vmsos721/6614/6614pro_contents.html" target="_blank">http://odl.sysworks.biz/disk$vaxdocmar002/opsys/vmsos721/6614/6614pro_contents.html</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Gene Cronin, Terence P. Sherlock (2000). COM Beyond Microsoft: Designing and Implementing COM Servers on Compaq Platforms. Digital Press. ISBN 1555582265. <a href="1555582265" target="_blank">1555582265</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"Home - TangramCOM". www.andjoin.com. Retrieved 2022-08-03. <a href="http://www.andjoin.com/Home" target="_blank">http://www.andjoin.com/Home</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> </ol>