Microsoft Distributed Component Object Model (DCOM)

The distributed object protocol from Microsoft (similar to CORBA but less powerful). As Microsoft is preferring SOAP for this kind of purpose now, you might call it a kind of obsolete.

Interfaces

DCOM uses interfaces and an interface description language (IDL) to define the interfaces/procedures available (it's all much like CORBA).

DCOM defines some common interfaces:

• IDispatch:
• IOxidResolver:
• IRemoteActivation:
• IRemoteUnknown/IRemoteUnknown2:
• ISystemActivator:

In addition to this, users can define and register their own interfaces.

History

Microsoft started DCOM with the name ORPC, an abbreviation of Object RPC, as you might find it in some documentation. XXX - add some more description of DCOM history

Protocol dependencies

• DCE/RPC: DCOM uses DCE/RPC as its transport protocol.

Example traffic

XXX - Add example traffic here (as plain text or Wireshark screenshot).

Wireshark

The DCOM dissector is partially implemented and a lot of dissection it still incomplete / buggy. However, often used methods are implemented, so the dissector should be useful.

Preference Settings

(XXX add links to preference settings affecting how DCOM is dissected).

Example capture file

XXX - Add a simple example capture file to the SampleCaptures page and link from here. Keep it short, it's also a good idea to gzip it to make it even smaller, as Wireshark can open gzipped files automatically.

Display Filter

A complete list of DCOM display filter fields can be found in the display filter reference.

Show only the DCOM based traffic:

 dcom

Capture Filter

You cannot filter DCOM protocols while capturing.

External links

• [MS-DCOM]: Distributed Component Object Model (DCOM) Remote Protocol - Recent DCOM specification (part of Microsoft's Open Specification)

  • DCE 1.1: Remote Procedure Call (C706) - DCE/RPC specification

  • [MS-RPCE]: Remote Procedure Call Protocol Extensions - MSRPC specification - Microsoft extensions to DCE/RPC

• Distributed Component Object Model Protocol -- DCOM/1.0 1998 version of DCOM/1.0 specification (internet draft)

• Understanding the DCOM Wire Protocol by Analyzing Network Data Packets

Discussion

Imported from https://wiki.wireshark.org/DCOM on 2020-08-11 23:12:34 UTC