STIX/TAXII - Complete Knowledge - 20/08/2023

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Introduction

STIX

What is STIX and what is TAXII? In the most simple terms STIX is a model of Threat Intelligence that is represented in motivations, abilities, capabilities and response objects. Those objects are then represented in either JSON (STIX 2) or XML (STIX 1).

Here is a very simple representation of STIX Objects in a graph. STIX Example Explanation of the example

The data can be helpful for preventing or mitigating various kinds of attacks that can be expressed with STIX. All the list of the examples you can find in their official example page.

TAXII

The STIX data has to be relayed in some way, that’s why we have the TAXII Server. It is a simple web server specifically created for storing and sharing that kind of data.

TAXII 1.x Structure

The TAXII 1.2 Server has the following structure:

Discovery Service - Within a POST request to their discovery URL (which should be pointed by the Server maintainers).
Collection Management URL - The service that has the collections with STIX objects.
Channels - Push/Subscribe pattern.

The full list of features for TAXII1 can be found in their official documentation:

TAXII 2.x Structure

For the newer versions of the TAXII Server we have the following structure:

Image description

/discovery - Discovers the paths to the different services provided by the Server.
api_roots - Provides the API URLs for the different types of Collection Management.
- collections - Provides the available collections for the given api_root.
  - collection/objects - Provides a list of STIX Objects in a given collection

You can see that this is very similar to the TAXII 1.x servers, there isn’t much of a difference in the structure besides that the collection_management_url is api_root in TAXII 2.x.

The full list of features for TAXII2 can be found in their official documentation.

TAXII Servers and Threat Intelligence Providers

The information about this is very scarce so I’ve gathered a quick list of the known providers for STIX data.

Resource	URL	Description	Data Type
AlienVault OTX	https://otx.alienvault.com/api	Requires an account, provides data in various ways including a TAXII Server.	STIX 1.x
Threat Connect	https://threatconnect.com/stix-taxii/	Requires an account, Paid service, (consumes and provides) threat intel.	STIX 1.x/2.x
EcleticIQ	https://www.taxiistand.com/	Test TAXII (v1x) server. (quite unstable and inconsistent)	STIX 1.x
Limo - Anomali	https://www.anomali.com/resources/limo	Test TAXII (v1x/v2x) server. Somewhat unstable but mostly fine during tests.	STIX 1.x/2.x

Tools for STIX/TAXII

The main tool for creating/parsing or generating STIX data is going to be Python, since that all of the tools created are written in Python. Of course there are other alternatives but currently that’s the most common one.

Other tools that might come in handy.

Tool	Description	Version
stix-shifter	Translates STIX to various other Threat Intelligence formats such as Carbon Black Cloud Query and others	STIX 1.x/2.x
stix2	The main python package to parse and use/create STIX2 data.	STIX 2.x
stix2-validator	Provides a validation for the STIX2 data, can be used to validate your data from your sources.	STIX 2.x
stix2-slider	Transforms STIX2 content to STIX1.2	STIX 2.x
stix2-elevator	Transforms STIX1 data to STIX2.x	STIX 1.x
stix	The main python package for STIX1 data.	STIX 1.x
stix-validator	Validating STIX1 data.	STIX 1.x
stix2-patterns	Validator and Pattern Parser for STIX 2.x Patterns	STIX 2.x
taxii2-client	Python Client for TAXII 2 Servers	TAXII 2.x
cabby	Python Client for TAXII 1 Servers	TAXII 1.x

Snippets and Gists

https://gist.github.com/syrull/6a2614560fb0474df166a51bcb34990d (Creating a TAXII2 Client for LimoAnomali)
https://gist.github.com/syrull/73b1798f90c4109a13ef9fceb1f2f858 (Creating a TAXII1 Client for OTXAlienVault)