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This repository provides Python APIs for serializing and de-serializing STIX 2 JSON content, along with higher-level APIs for common tasks, including data markings, versioning, and for resolving STIX IDs across multiple data sources.

Install with pip:

pip install stix2

To create a STIX object, provide keyword arguments to the type's constructor:

from stix2 import Indicator

indicator = Indicator(name="File hash for malware variant",
                      labels=['malicious-activity'],
                      pattern='file:hashes.md5 = "d41d8cd98f00b204e9800998ecf8427e"')

Certain required attributes of all objects will be set automatically if not provided as keyword arguments:

• If not provided, type will be set automatically to the correct type. You can also provide the type explicitly, but this is not necessary:

  indicator = Indicator(type='indicator', ...)

  Passing a value for type that does not match the class being constructed will cause an error:

  >>> indicator = Indicator(type='xxx', ...)
  stix2.exceptions.InvalidValueError: Invalid value for Indicator 'type': must equal 'indicator'.

• If not provided, id will be generated randomly. If you provide an id argument, it must begin with the correct prefix:

  >>> indicator = Indicator(id="campaign--63ce9068-b5ab-47fa-a2cf-a602ea01f21a")
  stix2.exceptions.InvalidValueError: Invalid value for Indicator 'id': must start with 'indicator--'.

• If not provided, created and modified will be set to the (same) current time.

For indicators, labels and pattern are required and cannot be set automatically. Trying to create an indicator that is missing one of these properties will result in an error:

>>> indicator = Indicator()
stix2.exceptions.MissingPropertiesError: No values for required properties for Indicator: (labels, pattern).

However, the required valid_from attribute on Indicators will be set to the current time if not provided as a keyword argument.

Once created, the object acts like a frozen dictionary. Properties can be accessed using the standard Python dictionary syntax:

>>> indicator['name']
'File hash for malware variant'

TBD: Should we allow property access using the standard Python attribute syntax?

>>> indicator.name
'File hash for malware variant'

Attempting to modify any attributes will raise an error:

>>> indicator['name'] = "This is a revised name"
TypeError: 'Indicator' object does not support item assignment
>>> indicator.name = "This is a revised name"
stix2.exceptions.ImmutableError: Cannot modify properties after creation.

To update the properties of an object, see Versioning below.

Creating a Malware object follows the same pattern:

from stix2 import Malware

malware = Malware(name="Poison Ivy",
                  labels=['remote-access-trojan'])

As with indicators, the type, id, created, and modified properties will be set automatically if not provided. For Malware objects, the labels and name properties must be provided.

STIX 2 Relationships are separate objects, not properties of the object on either side of the relationship. They are constructed similarly to other STIX objects. The type, id, created, and modified properties are added automatically if not provided. Callers must provide the relationship_type, source_ref, and target_ref properties.

from stix2 import Relationship

relationship = Relationship(relationship_type='indicates',
                            source_ref=indicator.id,
                            target_ref=malware.id)

The source_ref and target_ref properties can be either the ID's of other STIX objects, or the STIX objects themselves. For readability, Relationship objects can also be constructed with the source_ref, relationship_type, and target_ref as positional (non-keyword) arguments:

relationship = Relationship(indicator, 'indicates', malware)

STIX Bundles can be created by passing objects as arguments to the Bundle constructor. All required properties (type, id, and spec_version) will be set automatically if not provided, or can be provided as keyword arguments:

from stix2 import bundle

bundle = Bundle(indicator, malware, relationship)

The string representation of all STIX classes is a valid STIX JSON object.

indicator = Indicator(...)

print(str(indicator))

TBD

This GitHub public repository ( https://github.com/oasis-open/cti-python-stix2 ) was proposed and approved [bis] by the OASIS Cyber Threat Intelligence (CTI) TC as an OASIS Open Repository to support development of open source resources related to Technical Committee work.

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