184 lines
6.8 KiB
Python
184 lines
6.8 KiB
Python
"""STIX2 Core parsing methods."""
|
|
|
|
import copy
|
|
|
|
from . import registry
|
|
from .exceptions import ParseError
|
|
from .utils import _get_dict
|
|
|
|
|
|
def parse(data, allow_custom=False, version=None):
|
|
"""Convert a string, dict or file-like object into a STIX object.
|
|
|
|
Args:
|
|
data (str, dict, file-like object): The STIX 2 content to be parsed.
|
|
allow_custom (bool): Whether to allow custom properties as well unknown
|
|
custom objects. Note that unknown custom objects cannot be parsed
|
|
into STIX objects, and will be returned as is. Default: False.
|
|
version (str): If present, it forces the parser to use the version
|
|
provided. Otherwise, the library will make the best effort based
|
|
on checking the "spec_version" property. If none of the above are
|
|
possible, it will use the default version specified by the library.
|
|
|
|
Returns:
|
|
An instantiated Python STIX object.
|
|
|
|
Warnings:
|
|
'allow_custom=True' will allow for the return of any supplied STIX
|
|
dict(s) that cannot be found to map to any known STIX object types
|
|
(both STIX2 domain objects or defined custom STIX2 objects); NO
|
|
validation is done. This is done to allow the processing of possibly
|
|
unknown custom STIX objects (example scenario: I need to query a
|
|
third-party TAXII endpoint that could provide custom STIX objects that
|
|
I don't know about ahead of time)
|
|
|
|
"""
|
|
# convert STIX object to dict, if not already
|
|
obj = _get_dict(data)
|
|
|
|
# convert dict to full python-stix2 obj
|
|
obj = dict_to_stix2(obj, allow_custom, version)
|
|
|
|
return obj
|
|
|
|
|
|
def _detect_spec_version(stix_dict):
|
|
"""
|
|
Given a dict representing a STIX object, try to detect what spec version
|
|
it is likely to comply with.
|
|
|
|
:param stix_dict: A dict with some STIX content. Must at least have a
|
|
"type" property.
|
|
:return: A STIX version in "X.Y" format
|
|
"""
|
|
|
|
obj_type = stix_dict["type"]
|
|
|
|
if 'spec_version' in stix_dict:
|
|
# For STIX 2.0, applies to bundles only.
|
|
# For STIX 2.1+, applies to SCOs, SDOs, SROs, and markings only.
|
|
v = stix_dict['spec_version']
|
|
elif "id" not in stix_dict:
|
|
# Only 2.0 SCOs don't have ID properties
|
|
v = "2.0"
|
|
elif obj_type == 'bundle':
|
|
# Bundle without a spec_version property: must be 2.1. But to
|
|
# future-proof, use max version over all contained SCOs, with 2.1
|
|
# minimum.
|
|
v = max(
|
|
"2.1",
|
|
max(
|
|
_detect_spec_version(obj) for obj in stix_dict["objects"]
|
|
),
|
|
)
|
|
elif obj_type in registry.STIX2_OBJ_MAPS["v21"]["observables"]:
|
|
# Non-bundle object with an ID and without spec_version. Could be a
|
|
# 2.1 SCO or 2.0 SDO/SRO/marking. Check for 2.1 SCO...
|
|
v = "2.1"
|
|
else:
|
|
# Not a 2.1 SCO; must be a 2.0 object.
|
|
v = "2.0"
|
|
|
|
return v
|
|
|
|
|
|
def dict_to_stix2(stix_dict, allow_custom=False, version=None):
|
|
"""convert dictionary to full python-stix2 object
|
|
|
|
Args:
|
|
stix_dict (dict): a python dictionary of a STIX object
|
|
that (presumably) is semantically correct to be parsed
|
|
into a full python-stix2 obj
|
|
allow_custom (bool): Whether to allow custom properties as well
|
|
unknown custom objects. Note that unknown custom objects cannot
|
|
be parsed into STIX objects, and will be returned as is.
|
|
Default: False.
|
|
version (str): If present, it forces the parser to use the version
|
|
provided. Otherwise, the library will make the best effort based
|
|
on checking the "spec_version" property. If none of the above are
|
|
possible, it will use the default version specified by the library.
|
|
|
|
Returns:
|
|
An instantiated Python STIX object
|
|
|
|
Warnings:
|
|
'allow_custom=True' will allow for the return of any supplied STIX
|
|
dict(s) that cannot be found to map to any known STIX object types
|
|
(both STIX2 domain objects or defined custom STIX2 objects); NO
|
|
validation is done. This is done to allow the processing of
|
|
possibly unknown custom STIX objects (example scenario: I need to
|
|
query a third-party TAXII endpoint that could provide custom STIX
|
|
objects that I don't know about ahead of time)
|
|
|
|
"""
|
|
if 'type' not in stix_dict:
|
|
raise ParseError("Can't parse object with no 'type' property: %s" % str(stix_dict))
|
|
|
|
if not version:
|
|
version = _detect_spec_version(stix_dict)
|
|
|
|
OBJ_MAP = dict(
|
|
registry.STIX2_OBJ_MAPS[version]['objects'],
|
|
**registry.STIX2_OBJ_MAPS[version]['observables']
|
|
)
|
|
|
|
try:
|
|
obj_class = OBJ_MAP[stix_dict['type']]
|
|
except KeyError:
|
|
if allow_custom:
|
|
# flag allows for unknown custom objects too, but will not
|
|
# be parsed into STIX object, returned as is
|
|
return stix_dict
|
|
raise ParseError("Can't parse unknown object type '%s'! For custom types, use the CustomObject decorator." % stix_dict['type'])
|
|
|
|
return obj_class(allow_custom=allow_custom, **stix_dict)
|
|
|
|
|
|
def parse_observable(data, _valid_refs=None, allow_custom=False, version=None):
|
|
"""Deserialize a string or file-like object into a STIX Cyber Observable
|
|
object.
|
|
|
|
Args:
|
|
data (str, dict, file-like object): The STIX2 content to be parsed.
|
|
_valid_refs: A list of object references valid for the scope of the
|
|
object being parsed. Use empty list if no valid refs are present.
|
|
allow_custom (bool): Whether to allow custom properties or not.
|
|
Default: False.
|
|
version (str): If present, it forces the parser to use the version
|
|
provided. Otherwise, the default version specified by the library
|
|
will be used.
|
|
|
|
Returns:
|
|
An instantiated Python STIX Cyber Observable object.
|
|
|
|
"""
|
|
obj = _get_dict(data)
|
|
|
|
if 'type' not in obj:
|
|
raise ParseError("Can't parse observable with no 'type' property: %s" % str(obj))
|
|
|
|
# get deep copy since we are going modify the dict and might
|
|
# modify the original dict as _get_dict() does not return new
|
|
# dict when passed a dict
|
|
obj = copy.deepcopy(obj)
|
|
|
|
obj['_valid_refs'] = _valid_refs or []
|
|
|
|
if not version:
|
|
version = _detect_spec_version(obj)
|
|
|
|
try:
|
|
OBJ_MAP_OBSERVABLE = registry.STIX2_OBJ_MAPS[version]['observables']
|
|
obj_class = OBJ_MAP_OBSERVABLE[obj['type']]
|
|
except KeyError:
|
|
if allow_custom:
|
|
# flag allows for unknown custom objects too, but will not
|
|
# be parsed into STIX observable object, just returned as is
|
|
return obj
|
|
raise ParseError(
|
|
"Can't parse unknown observable type '%s'! For custom observables, "
|
|
"use the CustomObservable decorator." % obj['type'],
|
|
)
|
|
|
|
return obj_class(allow_custom=allow_custom, **obj)
|