[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: Re: Observable Patterning
> In order for a pattern to be specified in a STIX Indicator (e.g., ‘IP Address in 1.2.3.4/24’), would the pattern would need to use fields from a CybOX
object? If the answer is yes, does that create a hard dependency between STIX Indicator and a particular CybOX object and version?
Having a separate patterning structure would mean that we would somehow need to reference CybOX Object fields, and unless we completely decouple CybOX from STIX Indicators (this seems unlikely, though I believe there have
been a few suggestions to this effect), there would indeed be a hard dependency between a STIX Indicator and a particular CybOX Object version. This is necessary to explicitly specify the semantics of “what” the Indicator is looking for.
> What about consistency with other uses of STIX Indicator? Consider a SNORT signature or YARA rule – patterning is contained in those signatures and wouldn’t
be at the STIX Indicator level, which seems inconsistent to me.
This seems to be more of an issue with how different types of patterns are captured in STIX Indicators. CybOX-based patterns are currently represented as a separate entity, whereas other types
of patterns (SNORT, YARA, etc.) are captured as Test_Mechanisms. Given their functional overlap, it may make more sense to have a single “Pattern” field that can be extended to capture CybOX-based patterns, SNORT rules, YARA sigs, etc.
Regards,
Ivan
From: Mark Davidson
Date: Thursday, September 24, 2015 at 9:06 AM To: Trey Darley, Ivan Kirillov, "cti@lists.oasis-open.org" Subject: RE: Observable Patterning What implication would patterning in STIX Indicators have for the relationship between STIX Indicators and CybOX objects? In order for a pattern to be specified in a STIX Indicator (e.g., ‘IP Address in 1.2.3.4/24’), would the pattern would need to use fields from a CybOX
object? If the answer is yes, does that create a hard dependency between STIX Indicator and a particular CybOX object and version? What about consistency with other uses of STIX Indicator? Consider a SNORT signature or YARA rule – patterning is contained in those signatures and
wouldn’t be at the STIX Indicator level, which seems inconsistent to me. > Patterning should live in _one_ place and have _one_ syntax. I really like this idea, and I’m asking questions that I hope will lead us in this direction. Thank you. -Mark From:
cti@lists.oasis-open.org [mailto:cti@lists.oasis-open.org]
On Behalf Of Trey Darley +100, Ivan. Patterning should live in _one_ place and have _one_ syntax. I tend to think the STIX Indicator level is the right place for this to live. Cheers, Trey -- Trey Darley Senior Security Engineer Soltra | An FS-ISAC & DTCC Company
From:cti@lists.oasis-open.org
<cti@lists.oasis-open.org> on behalf of Kirillov, Ivan
A. <ikirillov@mitre.org> Relaunching this as a separate thread based on Jerome’s suggestion, so as to not further hijack the discussion around
Bernd’s suggested refactoring. I think there are a few broad questions around this topic that we can touch upon here: 1. What capabilities should STIX/CybOX patterning have? 2. Where should STIX/CybOX patterning live? 3. Should patterns have their own implementation/structure, or continue to be embedded in Observables/Objects? As far as 1) I would say the following, as a straw man: * Conditional operators * AND * OR * NOT * Basic temporal operators * FOLLOWED_BY * WITHIN * String matching * EQUALS * DOES_NOT_EQUAL * CONTAINS * DOES_NOT_CONTAIN * Basic arithmetic operators * > * < * >= * <= * Regular Expressions * PCRE compatible * Variable substitution
Regarding 2), it seems to me that patterning is inherent to Indicators, and thus should be part of STIX. I just can’t see the use case for a CybOX Observable with a pattern that
stands on its own, or is used in a non-Indicator context. This would also serve to greatly simplify CybOX, as it would mean that CybOX can ONLY capture instances of cyber data. With regards to 3), I see lots of advantages to having a separate structure for patterns, which I’ve documented in
the corresponding CybOX issue [1]. The short of it is that it will get rid of the instance/pattern duality, allow for the creation of a domain-specific patterning language (necessary for more complex pattern expressions), and also give us the flexibility to
move patterning out to wherever makes the most sense (whether it’s STIX or somewhere else). Regards, Ivan |
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]