| If you don’t mind funding a research project (hint, Rich), we could look into partial encryption and multi key encryption technologies to cryptographically guarantee that how you mark the data is how it is received.
Note that it is physically impossible, short of some kind of quantum crypto magic, to cryptographically enforce anything that lets people see plaintext at some point.
[Shameless self promotion] we do have a technology that does let you send around Snort filters, yet it is impossible to decode what the filters are, even down to monitoring the firewall. It’s not science fiction - we require two devices ;-)
Digital signatures and markings are different: digital signatures allow you as consumer to to be cryptographically sure that the producer who you think sent the message actually sent it and that it was not modified in any way. Markings allows me as a producer
to tell you how you should treat the content once you get it (who you can share it with, what you can do with it, etc).
We’ll need to talk about signing JSON at some point though, when we do we can look into RFC7515 (JSON Web Signatures).
John
Imagine that i am signing [0] (oops marking) my "TLP Red" objects à la PGP.
(Of course i defined my friends)
If you find a way for Alice and Bob in JSON please let me know
Warning: dont click (complexity)
On Thursday, 10 December 2015, Wunder, John A. < jwunder@mitre.org> wrote:
That’s a great point that totally slipped my mind.
In STIX 1.2, we said that the “marking scope” was limited to the construct itself. We didn’t say anything about the root of the document for purposes of evaluation (I just checked) so effectively it’s the root of the full package. Thus, as you say, it
was possible to mark things outside the actual scope. I don’t know why we did this…whether we just didn’t think about it or whether it was because it’s (relatively) hard to pull a snippet of XML out of a document and have it live on its own (due to namespace
mappings and things like that “higher” in the document that impact things at “lower” levels). So, in STIX 1.2, it’s up to the implementation to ensure that the things it marks are limited to the correct marking scope.
When defining this approach for STIX 1.2 I took a queue from JSON/JSONPath and considered just “re-rooting” the document. It’s very easy to do this in JSON because things higher in the document don’t impact things lower in the document, you can just pull
that chunk out and it will always be valid JSON. Given that freedom in the (presumed) MTI, for this proposal I defined it differently: the actual evaluation root for the controlled structure is the object itself, and therefore when evaluating it you can/should
just pull the chunk out completely and evaluate against that. That would prevent people from marking things outside the scope without requiring extra work on the implementation side.
If we develop an XML binding, we’ll have to figure out whether we need to override that and go back to the old approach. I would GUESS that this approach will still be better in XML even though you have to deal with namespace prefixes, but I’m not 100%
sure. We could always use one for JSON and a different one for XML though.
That actually brings up another important point: if we assume JSON MTI is one format among several, tools will have to evaluate data markings and then track them in their repositories
separate from the MTI approach, then be able to build and retransmit those markings in another format. In other words, if I take in JSON MTI I would need to evaluate that on the incoming JSON and store it in my database
somehow. If I want to transmit into protobuf, I can’t just use those JSONPath markings because they’re no longer valid…they have to be redone in whatever we define for Protobuf. Just something to think about regarding the “storing STIX natively” topic.
John
Moving to go deeper on L2 markings I would like more information on the restriction/enforcement of the scope of the specific field path.
Background and Questions: The L2 path is supposed to be limited to the "current" object however path syntax allow you reference other (eg parent, sibling, non-self) objects. Even given a regex to require the first characters reference the "current" object
a) how do we ensure the full path doesn't go outside of the current object?
b) if the full path goes outside of the current object, and what is the expected behavior?
Let's continue to narrow this discussion to conclusion.
-Marlon
From:
cti-stix@lists.oasis-open.org on behalf of Barnum, Sean D.
Sent: Tuesday, December 08, 2015 2:33:39 PM
To: Wunder, John A.; Jason Keirstead; Aharon Chernin
Cc:
cti-stix@lists.oasis-open.org
Subject: Re: [cti-stix] Applying data markings
I agree with John’s characterization here.
sean
Nope, for any of these approaches we rely on the client software to do the right thing and preserve data markings (as well as honor them in the first place).
For this reason, it seems to me that as long as we define the semantics for how markings are applied at the package level we don’t need to have them exist directly on the object. We can just define that they’re semantically equivalent and allow people
who are retransmitting objects to move them between the package and the object as they want (assuming of course that they preserve those semantics).
In other words, to me this would be a valid retransmission:
Org A => Org B
Org B => Org C
- Package
- Object 1 (TLP:RED)
- Object 2 (TLP:RED)
Yes, Org B is re-writing the object in the sense that they’re moving a marking there. But since semantically the marking was already there when it received it from Org A this seems fine to me. IMO resharers should be free to do things like this so long
as they don’t change the actual content of what they’re retransmitting.
OTOH if this is not something the community thinks is valid then I would lean more towards what Aharon is suggesting and require that people mark the objects directly, otherwise he’s right that they’ll get “stuck” because you can’t retransmit them outside
the context of the package that they came in.
John
" If you mark at the package level there is no enforcement within the object that it’s a specific TLP. I could take that object and use it in another document and document mark that object as TLP White.
This would work if and only if IDs are mandated to always be derrived based on hashing all of it's content, including any and all makings.
Is that something that was decided?
-
Jason Keirstead
Product Architect, Security Intelligence, IBM Security Systems
www.ibm.com/security |
www.securityintelligence.com
Without data, all you are is just another person with an opinion - Unknown
<graycol.gif>Aharon
Chernin ---12/07/2015 05:26:45 PM---I ask the group this, if your markings are at the package level, how do you reuse the objects? If yo
From: Aharon Chernin <achernin@soltra.com>
To: "Wunder, John A." <jwunder@mitre.org>, "cti-stix@lists.oasis-open.org"
<cti-stix@lists.oasis-open.org>
Date: 12/07/2015 05:26 PM
Subject: Re: [cti-stix] Applying data markings
Sent by: <cti-stix@lists.oasis-open.org>
I ask the group this, if your markings are at the package level, how do you reuse the objects? If you mark at the package level there is no enforcement within the object that it’s a specific TLP. I could take that object and use it in
another document and document mark that object as TLP White.
If we require markings at the object level, then you are protected by object revisioning rules, and potentially ID hashing. You could never change the TLP of the object and reuse that object without breaking the revisioning
rules or the ID hash.
I am not going to put up a huge fight here, but it just seems so obvious to me.
Aharon
From: <cti-stix@lists.oasis-open.org>
on behalf of "Wunder, John A." <jwunder@mitre.org>
Date: Monday, December 7, 2015 at 3:42 PM
To: "cti-stix@lists.oasis-open.org"
<cti-stix@lists.oasis-open.org>
Subject: Re: [cti-stix] Applying data markings
All,
I updated the proposal based on the comments from last week:
https://github.com/johnwunder/data-markings.
A few comments (on the comments…):
- Mark suggested renaming “Level 1” to “Data Markings” and “Level 2” to “Field Level Data Markings”. I initially made that change but found the language got very confusing so I switched it back.
- Per Aharon’s comments, this proposal does have markings at the package level for both L1 and L2. This allows you to mark everything in a package as TLP:RED in a single statement (not duplicated across each indicator). OTOH it also means
that if you discard the package you would need to have some way of tracking the markings separately. IMO that’s totally fine…it’s metadata about an object so it’s not like you’re changing the object itself if you add them to the object, and in any case per
Eric’s earlier e-mail I would imagine that after ingest your tool would probably be dealing with markings in something outside of STIX anyway (I certainly would, in particular for L2).
- Aharon commented that we were getting rid of XPath and that’s an advantage of this proposal. That’s true……...kind of. Replacing XML with JSON means we use JSONPath instead of XPath, but fundamentally it’s still a controlled structure
based approach with all the implementation complexity that it brings (as Bryan Worrell can tell you).
- That said, JSON is more straightforward than XML and so I think using it will minimize the occurrence of bugs like the ones we’ve had in the past with misunderstanding XPath.
To summarize things, here’s the open questions that I can think of (beyond “is this proposal good”):
1. Should the ability to handle Level 1 markings be MTI (mandatory to implement)? (
2. Should we spend further time investigating better approaches for L2 markings (Option 3, 4, others) or just go with this (Option 5)?
3. Should we keep markings at the package level or move all markings to the individual top-level objects?
My answers:
1. Not sure to be honest. Leaning towards not MTI.
2. We should use L2 as-is…it’s hard, but marking fields is hard and so IMO that’s fine. Most people will use L1 anyway.
3. Keep markings at the package level. This allows you to represent a “default” marking and override it. I also *think* (maybe I’m wrong) that certain entities in USG require package-level markings to represent “highest-classification”,
which means other gov’t may as well.
John
On Dec 7, 2015, at 10:43 AM, Cory Casanave <cory-c@modeldriven.com> wrote:
This does look like a good approach for message level markings.
Any information exchange, except for open data, is done under some explicit or implicit agreement between the parties. Various forms of such “exchange agreements” have been around for years. For example, the “Collaborative
Partner Profile Agreement” in EbXML, which came out of IBM. Having a reference to an exchange agreement provides the basis for trust between specific parties as well as an explicit representation of any categorization and/or restrictions on any exchange under
that agreement. For example, asserting that telephone numbers are personally identifiable information and that personally identifiable information shall not be stored. Markings in the “instance” document augment the exchange agreement. It would simply not
be practical or trustworthy to expect all such “markings” to be in every instance, so reference to an exchange agreement provides that level of trust and a place to put “generic” restrictions and categorizations. I suggest exchange agreements be considered
for CTI. The exchange agreement reference can be a kind of marking.
-Cory
From:cti-stix@lists.oasis-open.org [mailto:cti-stix@lists.oasis-open.org]
On Behalf Of Barnum, Sean D.
Sent: Monday, December 07, 2015 9:49 AM
To: Wunder, John A.; cti-stix@lists.oasis-open.org
Subject: Re: [cti-stix] Applying data markings
I fully support this option as would be expected.
Kudos to John for such a great writeup explaining the idea.
sean
From: "cti-stix@lists.oasis-open.org"
<cti-stix@lists.oasis-open.org> on behalf of John Wunder <jwunder@mitre.org>
Date: Thursday, December 3, 2015 at 3:11 PM
To: "cti-stix@lists.oasis-open.org"
<cti-stix@lists.oasis-open.org>
Subject: [cti-stix] Applying data markings
All,
I developed this proposal to handle the application of data markings in STIX 2.0:
https://github.com/johnwunder/data-markings. Note: it doesn't address the format of the markings themselves
(improvements to TLP, the work in FIRST, etc), just how those markings get applied to content.
I this this meets the need for simplicity for object-level markings as we’ve talked about many times while still allowing for more complicated field-level markings for those that need them. Please review the proposal and let’s talk about
feedback. If this looks good to everyone we could use it as the solution for issue #231 (currently #2 on our roadmap).
John
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