313 lines
12 KiB
Python
313 lines
12 KiB
Python
"""Python STIX2 Environment API."""
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import copy
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from .core import parse as _parse
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from .datastore import CompositeDataSource, DataStoreMixin
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class ObjectFactory(object):
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"""Easily create STIX objects with default values for certain properties.
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Args:
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created_by_ref (optional): Default created_by_ref value to apply to all
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objects created by this factory.
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created (optional): Default created value to apply to all
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objects created by this factory.
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external_references (optional): Default `external_references` value to apply
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to all objects created by this factory.
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object_marking_refs (optional): Default `object_marking_refs` value to apply
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to all objects created by this factory.
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list_append (bool, optional): When a default is set for a list property like
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`external_references` or `object_marking_refs` and a value for
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that property is passed into `create()`, if this is set to True,
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that value will be added to the list alongside the default. If
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this is set to False, the passed in value will replace the
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default. Defaults to True.
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"""
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def __init__(
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self, created_by_ref=None, created=None,
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external_references=None, object_marking_refs=None,
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list_append=True,
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):
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self._defaults = {}
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if created_by_ref:
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self.set_default_creator(created_by_ref)
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if created:
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self.set_default_created(created)
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if external_references:
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self.set_default_external_refs(external_references)
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if object_marking_refs:
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self.set_default_object_marking_refs(object_marking_refs)
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self._list_append = list_append
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self._list_properties = ['external_references', 'object_marking_refs']
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def set_default_creator(self, creator=None):
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"""Set default value for the `created_by_ref` property.
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"""
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self._defaults['created_by_ref'] = creator
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def set_default_created(self, created=None):
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"""Set default value for the `created` property.
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"""
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self._defaults['created'] = created
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# If the user provides a default "created" time, we also want to use
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# that as the modified time.
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self._defaults['modified'] = created
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def set_default_external_refs(self, external_references=None):
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"""Set default external references.
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"""
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self._defaults['external_references'] = external_references
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def set_default_object_marking_refs(self, object_marking_refs=None):
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"""Set default object markings.
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"""
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self._defaults['object_marking_refs'] = object_marking_refs
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def create(self, cls, **kwargs):
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"""Create a STIX object using object factory defaults.
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Args:
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cls: the python-stix2 class of the object to be created (eg. Indicator)
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**kwargs: The property/value pairs of the STIX object to be created
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"""
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# Use self.defaults as the base, but update with any explicit args
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# provided by the user.
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properties = copy.deepcopy(self._defaults)
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if kwargs:
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if self._list_append:
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# Append provided items to list properties instead of replacing them
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for list_prop in set(self._list_properties).intersection(kwargs.keys(), properties.keys()):
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kwarg_prop = kwargs.pop(list_prop)
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if kwarg_prop is None:
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del properties[list_prop]
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continue
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if not isinstance(properties[list_prop], list):
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properties[list_prop] = [properties[list_prop]]
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if isinstance(kwarg_prop, list):
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properties[list_prop].extend(kwarg_prop)
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else:
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properties[list_prop].append(kwarg_prop)
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properties.update(**kwargs)
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return cls(**properties)
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class Environment(DataStoreMixin):
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"""Abstract away some of the nasty details of working with STIX content.
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Args:
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factory (ObjectFactory, optional): Factory for creating objects with common
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defaults for certain properties.
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store (DataStore, optional): Data store providing the source and sink for the
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environment.
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source (DataSource, optional): Source for retrieving STIX objects.
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sink (DataSink, optional): Destination for saving STIX objects.
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Invalid if `store` is also provided.
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.. automethod:: get
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.. automethod:: all_versions
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.. automethod:: query
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.. automethod:: creator_of
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.. automethod:: relationships
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.. automethod:: related_to
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.. automethod:: add
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"""
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def __init__(self, factory=ObjectFactory(), store=None, source=None, sink=None):
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self.factory = factory
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self.source = CompositeDataSource()
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if store:
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self.source.add_data_source(store.source)
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self.sink = store.sink
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if source:
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self.source.add_data_source(source)
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if sink:
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if store:
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raise ValueError("Data store already provided! Environment may only have one data sink.")
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self.sink = sink
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def create(self, *args, **kwargs):
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return self.factory.create(*args, **kwargs)
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create.__doc__ = ObjectFactory.create.__doc__
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def set_default_creator(self, *args, **kwargs):
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return self.factory.set_default_creator(*args, **kwargs)
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set_default_creator.__doc__ = ObjectFactory.set_default_creator.__doc__
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def set_default_created(self, *args, **kwargs):
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return self.factory.set_default_created(*args, **kwargs)
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set_default_created.__doc__ = ObjectFactory.set_default_created.__doc__
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def set_default_external_refs(self, *args, **kwargs):
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return self.factory.set_default_external_refs(*args, **kwargs)
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set_default_external_refs.__doc__ = ObjectFactory.set_default_external_refs.__doc__
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def set_default_object_marking_refs(self, *args, **kwargs):
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return self.factory.set_default_object_marking_refs(*args, **kwargs)
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set_default_object_marking_refs.__doc__ = ObjectFactory.set_default_object_marking_refs.__doc__
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def add_filters(self, *args, **kwargs):
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return self.source.filters.add(*args, **kwargs)
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def add_filter(self, *args, **kwargs):
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return self.source.filters.add(*args, **kwargs)
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def parse(self, *args, **kwargs):
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return _parse(*args, **kwargs)
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parse.__doc__ = _parse.__doc__
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def creator_of(self, obj):
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"""Retrieve the Identity refered to by the object's `created_by_ref`.
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Args:
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obj: The STIX object whose `created_by_ref` property will be looked
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up.
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Returns:
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str: The STIX object's creator, or None, if the object contains no
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`created_by_ref` property or the object's creator cannot be
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found.
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"""
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creator_id = obj.get('created_by_ref', '')
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if creator_id:
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return self.get(creator_id)
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else:
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return None
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def semantically_equivalent(self, obj1, obj2):
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"""This method is meant to verify if two objects of the same type are
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semantically equivalent.
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Args:
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obj1: A stix2 object instance
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obj2: A stix2 object instance
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Returns:
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float: A number between 0.0 and 1.0 as a measurement of equivalence.
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Warnings:
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Not all objects are supported.
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Notes:
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This implementation follows the Committee Note on semantic equivalence.
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see `the Committee Note <link here>`__.
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"""
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equivalence_score = 0.0
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type1, type2 = obj1["type"], obj2["type"]
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if type1 != type2:
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raise ValueError('The objects to compare must be of the same type!')
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if obj1.get("spec_version", "") != obj2.get("spec_version", ""):
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raise ValueError('The objects to compare must be of the same spec version!')
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if type1 == "attack-pattern":
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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if _check_property_present("external_references", obj1, obj2):
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_partial_external_reference_based(obj1["external_references"], obj2["external_references"])
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elif type1 == "campaign":
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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if _check_property_present("aliases", obj1, obj2):
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_partial_list_based(obj1["aliases"], obj2["aliases"])
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elif type1 == "course-of-action":
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pass
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elif type1 == "identity":
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if _check_property_present("name", obj1, obj2):
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_exact_match(obj1["name"], obj2["name"])
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if _check_property_present("identity_class", obj1, obj2):
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_exact_match(obj1["identity_class"], obj2["identity_class"])
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if _check_property_present("sectors", obj1, obj2):
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_partial_list_based(obj1["sectors"], obj2["sectors"])
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elif type1 == "indicator":
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if _check_property_present("indicator_types", obj1, obj2):
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_partial_list_based(obj1["indicator_types"], obj2["indicator_types"])
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if _check_property_present("pattern", obj1, obj2):
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pass # TODO: needs to be done
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if _check_property_present("valid_from", obj1, obj2):
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_partial_timestamp_based(obj1["valid_from"], obj2["valid_from"])
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elif type1 == "instrusion-set":
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pass
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elif type1 == "location":
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pass
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elif type1 == "malware":
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if _check_property_present("malware_types", obj1, obj2):
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_partial_list_based(obj1["malware_types"], obj2["malware_types"])
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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elif type1 == "observed-data":
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pass
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elif type1 == "report":
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pass
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elif type1 == "threat-actor":
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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if _check_property_present("threat_actor_types", obj1, obj2):
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_partial_list_based(obj1["threat_actor_types"], obj2["threat_actor_types"])
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if _check_property_present("aliases", obj1, obj2):
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_partial_list_based(obj1["aliases"], obj2["aliases"])
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elif type1 == "tool":
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if _check_property_present("tool_types", obj1, obj2):
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_partial_list_based(obj1["tool_types"], obj2["tool_types"])
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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elif type1 == "vulnerability":
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if _check_property_present("name", obj1, obj2):
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_partial_string_based(obj1["name"], obj2["name"])
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if _check_property_present("external_references", obj1, obj2):
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_partial_external_reference_based(obj1["external_references"], obj2["external_references"])
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# TODO: need to actually calculate the value
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return equivalence_score
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def _check_property_present(prop, obj1, obj2):
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if prop in obj1 and prop in obj2:
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return True
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return False
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def _partial_timestamp_based(t1, t2):
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from .utils import parse_into_datetime
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tdelta = 1 # One day...
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stix_t1, stix_t2 = parse_into_datetime(t1), parse_into_datetime(t2)
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return 1 - min(abs(stix_t1.timestamp() - stix_t2.timestamp()) / (86400 * tdelta), 1)
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def _partial_list_based(l1, l2):
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l1_set, l2_set = set(l1), set(l2)
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return len(l1_set.intersection(l2_set)) / max(len(l1_set), len(l2_set))
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def _exact_match(val1, val2):
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if val1 == val2:
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return 1.0
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return 0.0
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def _partial_string_based(str1, str2):
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from pyjarowinkler import distance
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return distance.get_jaro_distance(str1, str2)
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def _partial_external_reference_based(refs1, refs2):
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pass # TODO: needs to be done
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def _partial_location_distance(loc1, loc2):
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pass # TODO: needs to be done
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