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Subject: Re: [cti] Re: [EXT] Re: [cti] Finalizing the STIX 2.1 Malware Object

Thanks Sean - no worries about the delayed reply. So as far as 2), are you suggesting that we make “results” required and that it can capture either the actual result or something more generic (e.g., malicious/benign/etc.) that could come from a vocabulary? I do agree with you that the current language around “results” being not required if there is no result is rather confusing and I would also rather make it required in all cases.





From: Sean Barnum <sean.barnum@FireEye.com>
Date: Tuesday, June 19, 2018 at 8:35 AM
To: Bret Jordan <Bret_Jordan@symantec.com>, Ivan Kirillov <ikirillov@mitre.org>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Subject: Re: [cti] Re: [EXT] Re: [cti] Finalizing the STIX 2.1 Malware Object


Sorry for the delayed response, Ivan.

This week I am actually in the midst of working through some significant evolution on our Malware object and its use.

I plan to attend today’s working call but am not sure what level of definitive opinions I will be ready to offer by then on very specific details. If not on today’s call we still should hopefully be able to offer some constructive input this week.


On your two items that started this thread I can offer the following though:

  1. FireEye would definitely support consolidating the _expression_ of the observables into a single location and referencing those from the various other places as appropriate. This is MUCH cleaner, simpler and more resilient.
  2. I would agree that it makes sense to make “product” required as it does not really make sense to capture/convey an av_results entry where you don’t convey which product was used. I would disagree with making “scanned” required. There are not uncommon use cases where you may wish to convey that samples were scanned with particular AV but specifically do not want to expose when those scans occurred as it exposes details of when you knew about them. Lastly, I would suggest that we modify the current definition of “result” slightly and make it required. Currently, the definition allows the lack of the “results” property to imply that the scan was successfully completed but did not classify the sample as malicious. This sort of implication seems to present significant risk of confusion. Rather, I propose that the “result” property be defined to explicitly convey the result of the scan (whether malicious or otherwise) and that it be required. We could also define a simple vocab for general results that could apply across any scanners (e.g. “malicious”, “suspicious”, “benign”, “unknown”, “error”, etc). Looking across the full set of properties currently in av-results-type, the two properties that seem to be necessary (any av-results instance would not really make any sense or be of value without them) are product and results. Telling people that a scan occurred (even if all the other details are included) but not saying which product was used is not very useful. The “scan” could have been my 5 year old niece looking at the file. Similarly, telling people that the sample was scanned (even if all the other details are included) but not saying the result of the scan is not very useful.


Sean Barnum

Principal Architect


M: 703.473.8262

E: sean.barnum@fireeye.com


From: <cti@lists.oasis-open.org> on behalf of Bret Jordan <Bret_Jordan@symantec.com>
Date: Monday, June 18, 2018 at 5:04 PM
To: "Kirillov, Ivan A." <ikirillov@mitre.org>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Subject: [cti] Re: [EXT] Re: [cti] Finalizing the STIX 2.1 Malware Object


I will try and review this change this week.



From: cti@lists.oasis-open.org <cti@lists.oasis-open.org> on behalf of Kirillov, Ivan A. <ikirillov@mitre.org>
Sent: Monday, June 18, 2018 10:26:15 AM
To: cti@lists.oasis-open.org
Subject: [EXT] Re: [cti] Finalizing the STIX 2.1 Malware Object


Are there any other thoughts on these topics? It would be great to close them out so we can finish up CSD01 of STIX 2.1.





From: <cti@lists.oasis-open.org> on behalf of Ivan Kirillov <ikirillov@mitre.org>
Date: Wednesday, June 13, 2018 at 2:47 PM
To: Allan Thomson <athomson@lookingglasscyber.com>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Cc: "Kumar, Subodh" <subodh.kumar@jpmorgan.com>
Subject: Re: [cti] Finalizing the STIX 2.1 Malware Object


Sorry, that should read “Conversely, parsing the SDO may become more difficult because…”





From: Ivan Kirillov <ikirillov@mitre.org>
Date: Wednesday, June 13, 2018 at 2:44 PM
To: Allan Thomson <athomson@lookingglasscyber.com>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Cc: "Kumar, Subodh" <subodh.kumar@jpmorgan.com>
Subject: Re: [cti] Finalizing the STIX 2.1 Malware Object


Hi Allan,


This approach doesn’t fundamentally change how we capture static/dynamic analysis data, but rather where and how the Cyber Observable Objects that correspond to that data are stored. If you have multiple observables from different analyses, you’ll just reference their corresponding objects that are stored in the “observable_objects” dictionary (which may or may not be the same objects across different analyses).

As far as being easier, it’s kind of a wash – it may simplify the generation of content because any Cyber Observable Objects would have to be stored in this top-level dictionary. Conversely, parsing the SDO because you’ll have to dereference the objects as you come across their usage. However, I do think that the simplification to the data model and the ability to re-use objects are worthwhile changes.





From: Allan Thomson <athomson@lookingglasscyber.com>
Date: Wednesday, June 13, 2018 at 2:22 PM
To: Ivan Kirillov <ikirillov@mitre.org>, "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Cc: "Kumar, Subodh" <subodh.kumar@jpmorgan.com>
Subject: Re: [cti] Finalizing the STIX 2.1 Malware Object


Ivan – regarding 1.


What if I have multiple observables for the same malware from different analysis (i.e. static + dynamic results).


Would consolidating them into a single place really make it easier? You would still want to indicate that you have a list of observables and indicate where those were ‘observed’ from either static or dynamic or other.


So I’m not sure consolidating it makes it easier but so long as the same things are possible with the consolidated design then I don’t have a strong preference either way.


Allan Thomson

CTO (+1-408-331-6646)

LookingGlass Cyber Solutions


From: "cti@lists.oasis-open.org" <cti@lists.oasis-open.org> on behalf of "Kirillov, Ivan" <ikirillov@mitre.org>
Date: Wednesday, June 13, 2018 at 12:57 PM
To: "cti@lists.oasis-open.org" <cti@lists.oasis-open.org>
Cc: "Kumar, Subodh" <subodh.kumar@jpmorgan.com>
Subject: [cti] Finalizing the STIX 2.1 Malware Object




As we’re wrapping up work on STIX 2.1 CSD01, we need to finalize what we have for the updated Malware SDO. Accordingly, I have two topics I’d like to bring up in this regard:


  1. Thanks to the work done by Subodh Kumar and his team, I’ve been wondering if there’s a better way to capture the Observable Objects associated with the Malware SDO. Right now, there are three places where you may encounter a Cyber Observable Object: samples (a dict of observable objects), static_analysis_results/results (certain keys have a corresponding dict of observable objects), dynamic_analysis_results/results (each key has a corresponding dict of observable objects).  


Instead of having these observable object dictionaries all over the place, I believe it would make more sense to have a single property at the top level of the object (let’s call it “observable_objects”), where any Cyber Observable Objects associated with the SDO (samples, analysis results, etc.) could be captured, via references. There are a number of advantages to this: a simpler data model (less embedded observable object dicts everywhere), the ability to re-use objects (e.g., if static and dynamic analysis find the same objects, you can create one object and just reference it accordingly), and a more compact serialization. See the attached JSON example for what this looks like in practice – this is a modified version of the “Malware Instance with Analysis Data” example currently in the 2.1 spec.


  1. Currently, the “av-results-type”, used to capture AV classification results, has only optional properties and the text specifies that at least one must be included. This allows you to construct some odd, but spec-valid instances, such as an AV classification with only the engine version. In order to make this type more useful, I’d suggest that we make “product” (the name of the tool performing the scan) and “scanned” (the date/time the scan occurred) required, so that way you’ll at least have this minimum set of useful data for each instance. In addition, we should probably add some text stating that the “result” property (the actual AV classification result, e.g., “Trojan.Zeus”) must be included if the tool reports some classification during the scan.


Let me know what you think – if we can get these final things wrapped up, we’re that much closer to getting STIX 2.1 out the door.




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