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Subject: Re: [cti] Re: [EXT] Re: [cti] Working Call Recap
>>4) Drew is correct, we removed the spec_version from Bundle because we realized that using a spec_version on bundle to describe the spec version of the content in side the bundle
was wrong. I disagree with this characterization. I do not believe it was in any way demonstrated to be wrong. Some parties simply preferred to try to handle it in TAXII instead. And I think everyone
got tired of arguing about it. 😉 >> But these properties would no longer be an option on SCOs themselves. I would strongly disagree with an approach that removes them from the SCOs. As discussed, if we allowed the properties on Bundle as a default assertion for the contained content we would
still need them at the property level as an override for contained objects that differ from the default values at the Bundle level. This is a very straightforward approach for people to understand and to implement. >>I would also suggest that we add the spec_version back to Bundle and say that it represents the spec version of the Bundle container. This way we can add extra meta data "things" to the bundle
at a later time if needed. I would agree with this.
Comments inline below Sean Barnum Principal Architect FireEye M: 703.473.8262 E: sean.barnum@fireeye.com From: Bret Jordan <Bret_Jordan@symantec.com> Allan, that is a great point about option C requiring a created_by_ref on the SCOs. I think we could do both A and B though. Doing one does not prevent us from doing the other. [sdb] I strongly support A & B. I know Allan you proposed this before and it did not end up making it out of the last F2F. But I am beginning to see the sure wisdom of it. Maybe we need a bundle for SCOs (I think you called it a fact-list).
Then we could add this at various levels. [sdb] I am not a fan of a separate bundle for SCOs as I not really see a need for it. That being said, I would not object to it if others see a need given their use cases. My only caveat is that we do not presume that everyone would use it and do not
try to put information such as we are discussing here (id_method/id_method_details) only on such an object.
I know that you have not proposed that here, I am just making the caveat clear for any future discussion. We could add the properties to the STIX Bundle for people that want to do it there or say how even their SDO and SRO IDs are created. [sdb] Strongly support this approach for this use case. We could also add them to a SCO-LIST object and also add the "created_by_ref" to it. That way if someone wanted to do this via the identifier they could for SCOs. The identifier would also work for SDOs and SROs
out of the box. [sdb] I am not exactly clear on what you are saying here. We could add these in TAXII as well, for content that is shared inside an envelope. [sdb] I think this is a good idea as this is a separate use case from STIX Bundle. I am just trying to offer up various solutions that we could do, even do ALL of them to address this. This is really just meta data we are talking about. So doing it in different places or at different levels
would be okay, IMO. The order of significance would be id_methods on the SCO-LIST, id_methods on the Bundle, and the least significant would be id_methods on the identity. Meaning, if it was defined on the SCO-List it would override what was on the identity. [sdb] I worry about trying to make it too complex though. I believe that having it at the Bundle as a default and at the object level as an override gracefully handles the issue simply, gracefully and in a way that is easy to implement. Another option is to JUST do this via the identity. This would require a SCO-LIST with a created_by_ref. But that is an option. Then if someone wanted to just use the identity object to do this as they had decided
internally that they would always do it the same way. Then this becomes SUPER simple. All SDOs and SROs etc already have a created_by_ref. The SCO-LIST would have a created_by_ref. And everything would be solved. [sdb] I am not a fan of an approach of placing this on an Identity object for various reasons, one of which is that a given producer may use different methods for different output streams. As was previously discussed, the properties relevant to calculating a deterministic id may vary not only from producer to producer but also based on particular use cases. A given producer may produce STIX content for multiple use cases that differ
in their appropriate id-relevant properties. Bret From: Allan Thomson <athomson@lookingglasscyber.com> Thanks Bret. I would be fine with any of the suggested options a) bundle changes b) taxii envelope changes c) identity properties where that identity is associated with creation of the object. My preference would lie primarily with either a) or b). With a slight preference for a) because a bundle is and can be used to provide a wrapper of STIX content outside of TAXII transport whereas making the change for a TAXII transport
only fixes TAXII not all cases on how STIX is exchanged. The challenge with c) is that it would still require a property on every SCO to point to the identity creating the SCO and that somewhat defeats the purposes of a SCO (given that they are meant for re-use across any vendor that uses the
same deterministic id). allan From:
Bret Jordan <Bret_Jordan@symantec.com> All, I would like to step back and focus this discussion a bit, since we seem to be all over the place. First a bit of background to bring everyone up to speed. 1) Back at the DC3 F2F the main objection to having SCOs be TLOs was the explosion of objects with the same data (e.g.. ip address 1.2.3.4). At that point, many said we could use deterministic IDs, but also at
that point NO ONE has produced a solid proposal for how that could or should be done. Thanks to Allan's works, we now have a solution that solves that problem. 2) Some people will want to use deterministic IDs to try and figure out of content is the same or not. On the flip side, some people will not care at all, and will just treat every IDs as unique. We can not force
people to pay attention to the IDs. 3) It is super critical that we do not have un-intended collisions on IDs. The importances of this is carved in stone. Our whole versioning model and graph design hinges on this. 4) Drew is correct, we removed the spec_version from Bundle because we realized that using a spec_version on bundle to describe the spec version of the content in side the bundle was wrong. 5) A bundle in STIX or an envelope in TAXII can contain meta data about the data it transmits. This is perfectly valid. 6) There has been significant concerned raised many times over about bloat on SCOs. We also need to remember as Allan reminds us, that STIX is about "TRANSPORT" it is not about how your local system stores or uses
data locally. It is an "interchange" format. As such, we should constantly remind ourselves of that. Yes, even I need to be reminded of this from time to time. My _personal_ proposal: We no longer look at "id_method" and "id_method_details" as common properties. We do, however, add them to the STIX Bundle and we may consider adding them to the TAXII envelope and or TAXII http headers. But these
properties would no longer be an option on SCOs themselves. I would also be open to adding these properties to an identity object as well. This way if someone wanted to say that they "ALWAYS" generate their IDs in this method, they can just do it via the
identity object. Producers SHOULD tell consumers about how their IDs were created. But they are not required to do so. What they are required to do is guarantee that non-SCO ID's are globally unique and do not un-intentionally
collide with someone else's IDs. Meaning, they SHOULD be UUIDv4 or the likes. If they want to use UUIDv5 then it is up to them to figure out a namespace and such that makes sure they do not collide. For consumers that want to know and track the information about how the IDs were created, they can. If they do not care, they do not care. For organizations that want to track how the IDs were created so they can
re-share that information back out, then they can do so, how ever they want in their datastore. But these fields will not be used as part of any future digital signatures as they are purely meta-data that may be learned outside of STIX. I would also suggest that we add the spec_version back to Bundle and say that it represents the spec version of the Bundle container. This way we can add extra meta data "things" to the bundle at a later time if
needed. Bret From: Sean Barnum <sean.barnum@FireEye.com> > Bundles are a way to package STIX objects. They are not âtheâ way to package them. TAXII 2.1 packages them in an Envelope without a Bundle. Sure, but this proposal does not require anyone to use Bundle. If a producer/sharer wanted to exchange objects via TAXII without a Bundle (which I do not necessarily recommend) they would need to assert the properties on each object. This proposal is simply providing a mechanism for producers/sharers who choose to use Bundle to convey their content in a vastly more efficient way that makes it practical/possible to use. This does not preclude anyoneâs choices on how they wish to share. It simply provides a viable option for a portion of the community to be able to use STIX to share. The alternative of forcing the properties onto ALL SCOs would basically double the size of most commonly shared high volume SCOs (IP addresses, URLs, DomainNames, etc). Bloat like that would make STIX impractical for many users and the
Bundle approach proposal at hand offers a simple and effective solution. Sean Barnum Principal Architect FireEye M: 703.473.8262 E: sean.barnum@fireeye.com From:
"drew.varner@ninefx.com" <drew.varner@ninefx.com> We removed it in 2.1 because we realized that a bundle could contain objects of multiple versions. STIX objects have a spec_version property so they are now-self-describing.
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