Re: [cti] Re: [EXT] [cti] Embedded Relationships

[Allan Thomson <athomson@lookingglasscyber.com>]

Nathan – KMIP represents at least 5 years of time (and many more years in work) with many contributions.

 

We happily welcome contributions to the Interop specification work that is ongoing in STIX/TAXII to improve what we have defined for personas and the interoperability of the standard work.

 

So far we have focused on STIX as TAXII 2 has not yet finalized (enough). Now that TAXII 2 is getting close the Interop group will start considering how to define interop for TAXII capabilities as well.

 

Please join the interop group and contribute. That is the way our community improves and builds a good specification.

 

It does not happen itself or without people getting involved to write specs.

 

Regards

 

Allan

 

 

From: "Reller, Nathan S." <Nathan.Reller@jhuapl.edu>
Date: Friday, May 5, 2017 at 7:01 AM
To: Jason Keirstead <Jason.Keirstead@ca.ibm.com>
Cc: Terry MacDonald <terry.macdonald@cosive.com>, Allan Thomson <athomson@lookingglasscyber.com>, Bret Jordan <Bret_Jordan@symantec.com>, "Struse, Richard" <Richard.Struse@hq.dhs.gov>, John-Mark Gurney <jmg@newcontext.com>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Subject: Re: [cti] Re: [EXT] [cti] Embedded Relationships

 

> Again, you are assuming that people are always occupying the "repository" persona. There are many personas for TAXII, not all of which store data. I highly suggest you take a look at the personas defined in the Interoperability Subcommittee's use case specification - https://docs.google.com/document/d/1l54RhjxwuXrZUQ19zIHUiZ7_c6otbLbVVfluKJogU7s/edit#heading=h.4do73o99e2l7

 

OK, now I understand. In the specification for TAXII I was reading Section 8 as meaning that all functions must be implemented because it says, “It MUST support all requirements as defined in section 3, section 4 and section 5.” It was unclear to me what that really meant, but all of the collections API stuff is in Section 5. With such a small spec it seemed to me that I must implement all of the methods. Here you are saying that I do not.

 

I would suggest making it clearer that you do not need to implement all of the methods and functionality. I would compare this to the OASIS KMIP spec that does clearly indicate there are different profiles and what methods and objects need to be implemented for each profile. They even have a separate document to list all of the different profiles, which I think you are calling personas although I don’t quite get that feeling after skimming through the document you linked. In the KMIP world if you don’t implement an operation then you MUST return an error action of “Operation Failed” with reason “Operation Not Supported.” Perhaps that is the intent of the 404 error, but I did not read it that way. The KMIP spec also provides a Query method that returns all of the supported operations. This way a client can verify what type of KMIP server it is talking to.

 

KMIP v1.3 spec:

http://docs.oasis-open.org/kmip/spec/v1.3/os/kmip-spec-v1.3-os.html

 

KMIP v1.3 profiles:

http://docs.oasis-open.org/kmip/profiles/v1.3/os/kmip-profiles-v1.3-os.html

 

In addition to making it clear that not all operations needed to be supported the profiles document provides a nice checklist of what objects and functions need to be implemented. As we implemented the KMIP spec for our open source library PyKMIP it was nice to have a checklist of what needed to be implemented. For instance, we first wanted to support symmetric keys. There is a profile called “Symmetric Key Lifecycle Profiles” and it tells me which algorithms and key types I need to implement. It seems like there is some of that in the personas document, but in my opinion I think the KMIP format is much cleaner to read. The nice part about the personas document is that it provides more context, so maybe we could combine the approaches? I think that would be very helpful to readers.

 

Symmetric Key Lifecycle Profiles:

http://docs.oasis-open.org/kmip/profiles/v1.3/os/kmip-profiles-v1.3-os.html#_Toc473103134

 

For what it’s worth, KMIP Specification 1.3 and KMIP Profiles 1.3 are finalists for the “Outstanding Approved Standard” at the 2017 Open Standards Cup.

 

-Nate

 

 

From: Jason Keirstead <Jason.Keirstead@ca.ibm.com>
Date: Thursday, May 4, 2017 at 2:10 PM
To: "Reller, Nathan S." <Nathan.Reller@jhuapl.edu>
Cc: Terry MacDonald <terry.macdonald@cosive.com>, Allan Thomson <athomson@lookingglasscyber.com>, Bret Jordan <Bret_Jordan@symantec.com>, "Struse, Richard" <Richard.Struse@hq.dhs.gov>, John-Mark Gurney <jmg@newcontext.com>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Subject: Re: [cti] Re: [EXT] [cti] Embedded Relationships

 

> Could you further explain this? I don’t understand how something can be a TAXII server but not have a historical database.
> I feel that it must have some repository/database of information to store the POSTed objects temporarily until a TAXII client
> does a GET request. Otherwise where do you get the STIX objects that are used in steps 4 and 6 above? A proxy I get,
> but that is really just a middle-man between a real TAXII server.

Again, you are assuming that people are always occupying the "repository" persona. There are many personas for TAXII, not all of which store data. I highly suggest you take a look at the personas defined in the Interoperability Subcommittee's use case specification - https://docs.google.com/document/d/1l54RhjxwuXrZUQ19zIHUiZ7_c6otbLbVVfluKJogU7s/edit#heading=h.4do73o99e2l7

Just because you POST TAXII information to me, does not mean you can then later GET that same information from me, because I may not be acting as any kind of repository. I may not even have a TAXII "read" facility at all, and only accept POSTs to a channel or collection, and all GETs against the channel or collection return empty all the time. A use case for this may be a device that wants to expose a TAXII collection or channel to allow people to submit CTI to it to trigger some action, such as adding something to a watch list or launching a remediation. As such, I have no need to store this information at all, anywhere.

Or, to flip it around, I may offer a read-only view of a channel or collection and not anyone to ever POST anything to it at all. A use case for this might be a proxy device that exposes live sighting information on a channel or collection. This information would all be read-only, live, streaming data from the device.... there is no repository, and if you go back to that device in an hour those objects wouldn't even exist on it anymore.

-
Jason Keirstead
STSM, Product Architect, Security Intelligence, IBM Security Systems
www.ibm.com/security

Without data, all you are is just another person with an opinion - Unknown