Question

I’m trying to design an application that can identify COM objects and their properties on any different application. This is my first time attempting to do so, and I’m not sure where to start even. Ideally, it would be made using Delphi XE2, but I’m open to suggestions.

If I have the CLSID, is there any way to “scan” a running application for what objects were based on it? Or, going another way, is there a better way to list/find active objects in any running application?

Any help is deeply appreciated, as well as any directions towards good documentation on the subject.

Edit: The issue is actually finding out the COM objects in any other application, listing properties and whatever else I need has already been answered in other questions.

Answer 1

There is no way to scan for running COM objects. As soon as they are instantiated – they are just pieces of memory referenced by something else (member interface pointer variables etc).

Sometimes objects are put on Running Objects Table (ROT) and you can retrieve them from there, as already suggested in comments. This attributes for, let’s say, <1% of COM object instances, but maybe you are lucky enough to chase for exactly those.

The only way I can think of is hook COM object instantiation in so that you intercept creation and then be able to track your own list of existing instances. This is not an easy way though too (and also it is most likely to be unsafe).

To achieve this you need to either register your class object in the context of running process for the CLSID of your interest and have your class factory receive the instantiation calls. Or, hook CoCreateInstance API, such as with Detours.

Once you are hooking instantiation you have pointers at the moment of object creation and you again need to do something with them. You would want to forward those instantiation calls to the original API, then to track life time of the instances – if you put an extra reference to the object you are likely to alter the original behavior of the application. Otherwise, you have no control to intercept COM object release. Sometimes the COM classes can be created aggregated and you can more or less cleanly embed the original instance in your COM object.

All in all, in general the task does not seem feasible to implement. Having specific CLSID of interest, with a certain luck and quite some effort you might be successful in doing this though.