METRON-1102: Add support for ingesting cybox URI observables from taxii feeds

[cestella]

Contributor Comments

There is value in ingesting URIs from taxii feeds and we should provide support to do so.

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[cestella]

Testing plan should be the same as here

[simonellistonball]

Didn't we change how logging worked in METRON-975? @mmiklavc see also #599

[cestella]

Yeah, this ended up starting live as a patch against an older branch that I just made current. I changed the logging to use slf4j now. Good eye, @simonellistonball

[ottobackwards]

So,

I think this is a great addition, but I have some comments.

• Where is the documentation for the version of Stix and the Version of Cybox metron supports?
• How is the extractor factored to handle support for other versions?
• How is the extractor factored to handle JSON if / when stix and cybox change over?
• Can we handle just Cybox? Should this be factored to support them separately?
• Where is the documentation for the support in this PR?

[cestella]

Ok, so good questions @ottobackwards . I'll do my best to answer them, but the answer to some of these expands past this PR and to the history of Taxii support for Metron (which was one of the first things we added and thus at a period of time where documentation was scarcer than it is even now ;) )

• Where is the documentation for the version of Stix and the Version of Cybox metron supports?
  We do not currently document that, the answer is, however, that our support for Stix, cybox and taxii is entirely bound up in the mitre java-stix library. We use the most current version released, which is 1.2.0.2.

• How is the extractor factored to handle support for other versions?
  The extractor is handled to support other versions only insomuch as the java-stix library can support multiple versions. As this is officially supported by the stix project, I think that it's backwards compatible, but there may be nuance here that I'm missing.

• How is the extractor factored to handle JSON if / when stix and cybox change over?
  The extractor abstraction works at the level of the object model that the java-stix library provides us rather than doing actual parsing (i.e. we implement support for new types by providing a handler that looks for objects of that type as the output of the parse). If Stix moves to JSON, presumably the library will handle that transparently or we'll need another approach.

• Can we handle just Cybox? Should this be factored to support them separately?
  We can create handlers for anything the java-stix library can parse, but cybox seems to be common and officially supported by the stix project.

• Where is the documentation for the support in this PR?
  I added the new URI type to the README.md in metron-data-management. Since that's the scope of this PR, not to document better our taxii/stix/etc support.

Ok, so it's apparent that some of the design decisions around taxii never made it into documentation. A couple of questions for you:

• Where should that documentation live?
• Are we unhappy enough about having our abstraction bound to the (from what I can tell only) java library provided by the stix project that you'd like to start a discuss thread about developing a better approach to taxii?

Just a note on the second, we chose that because it was the only game in town other than parsing the XML ourselves and it was the officially supported library. I even looked into that and decided against it as the XML format is extremely complex with lots of referential links that need to get coalesced to handle the blocks of stix that come across.

[ottobackwards]

Can we handle just Cybox

What I mean is, can we import a file that is ONLY cybox observables, without Stix.

Stix supports cybox. But they are separate things.

[ottobackwards]

As for where... over in METRON-777 @mmiklavc is talking about a better documentation area... this may fall into that

[cestella]

Ah, for the moment we only have the StixExtractor. We could MAKE a cybox extractor and it could reuse the handler logic, but we haven't done that. Have you seen people ingesting cybox (or stix for that matter) outside of taxii?

[cestella]

Yeah, it seems to me that we might need something like a location for discussion and description of architectural decisions made.

[ottobackwards]

I would like to see at least the version of Stix and Cybox that is supported documented.

[cestella]

Sure, not a problem. I noted the versions supported in the documentation and linked to the actual schemata for cybox and stix.

[ottobackwards]

+1 by inspection.