xforceexchange.py

import requests
import json
import sys
from . import check_input_attribute, standard_error_message
from collections import defaultdict
from pymisp import MISPAttribute, MISPEvent, MISPObject
from requests.auth import HTTPBasicAuth

sys.path.append('./')

misperrors = {'error': 'Error'}
mispattributes = {'input': ['ip-src', 'ip-dst', 'vulnerability', 'md5', 'sha1', 'sha256', 'domain', 'hostname', 'url'],
                  'output': ['ip-src', 'ip-dst', 'text', 'domain'],
                  'format': 'misp_standard'}

# possible module-types: 'expansion', 'hover' or both
moduleinfo = {'version': '2', 'author': 'Joerg Stephan (@johest)',
              'description': 'IBM X-Force Exchange expansion module',
              'module-type': ['expansion', 'hover']}

# config fields that your code expects from the site admin
moduleconfig = ["apikey", "apipassword"]


class XforceExchange():
    def __init__(self, attribute, apikey, apipassword):
        self.base_url = "https://api.xforce.ibmcloud.com"
        self.misp_event = MISPEvent()
        self.attribute = MISPAttribute()
        self.attribute.from_dict(**attribute)
        self._apikey = apikey
        self._apipassword = apipassword
        self.result = {}
        self.objects = defaultdict(dict)
        self.status_mapping = {403: "Access denied, please check if your authentication is valid and if you did not reach the limit of queries.",
                               404: "No result found for your query."}

    def parse(self):
        mapping = {'url': '_parse_url', 'vulnerability': '_parse_vulnerability'}
        mapping.update(dict.fromkeys(('md5', 'sha1', 'sha256'), '_parse_hash'))
        mapping.update(dict.fromkeys(('domain', 'hostname'), '_parse_dns'))
        mapping.update(dict.fromkeys(('ip-src', 'ip-dst'), '_parse_ip'))
        to_call = mapping[self.attribute.type]
        getattr(self, to_call)(self.attribute.value)

    def get_result(self):
        if not self.misp_event.objects:
            if 'error' not in self.result:
                self.result['error'] = "No additional data found on Xforce Exchange."
            return self.result
        self.misp_event.add_attribute(**self.attribute)
        event = json.loads(self.misp_event.to_json())
        result = {key: event[key] for key in ('Attribute', 'Object') if (key in event and event[key])}
        return {'results': result}

    def _api_call(self, url):
        try:
            result = requests.get(url, auth=HTTPBasicAuth(self._apikey, self._apipassword))
        except Exception as e:
            self.result['error'] = e
            return
        status_code = result.status_code
        if status_code != 200:
            try:
                self.result['error'] = self.status_mapping[status_code]
            except KeyError:
                self.result['error'] = 'An error with the API has occurred.'
            return
        return result.json()

    def _create_file(self, malware, relationship):
        file_object = MISPObject('file')
        for key, relation in zip(('filepath', 'md5'), ('filename', 'md5')):
            file_object.add_attribute(relation, malware[key])
        file_object.add_reference(self.attribute.uuid, relationship)
        return file_object

    def _create_url(self, malware):
        url_object = MISPObject('url')
        for key, relation in zip(('uri', 'domain'), ('url', 'domain')):
            url_object.add_attribute(relation, malware[key])
        attributes = tuple(f'{attribute.object_relation}_{attribute.value}' for attribute in url_object.attributes)
        if attributes in self.objects['url']:
            del url_object
            return self.objects['url'][attributes]
        url_uuid = url_object.uuid
        self.misp_event.add_object(**url_object)
        self.objects['url'][attributes] = url_uuid
        return url_uuid

    def _fetch_types(self, value):
        if self.attribute.type in ('ip-src', 'ip-dst'):
            return 'ip', 'domain', self.attribute.value
        return 'domain', 'ip', value

    def _handle_file(self, malware, relationship):
        file_object = self._create_file(malware, relationship)
        attributes = tuple(f'{attribute.object_relation}_{attribute.value}' for attribute in file_object.attributes)
        if attributes in self.objects['file']:
            self.objects['file'][attributes].add_reference(self._create_url(malware), 'dropped-by')
            del file_object
            return
        file_object.add_reference(self._create_url(malware), 'dropped-by')
        self.objects['file'][attributes] = file_object
        self.misp_event.add_object(**file_object)

    def _parse_dns(self, value):
        dns_result = self._api_call(f'{self.base_url}/resolve/{value}')
        if dns_result.get('Passive') and dns_result['Passive'].get('records'):
            itype, ftype, value = self._fetch_types(dns_result['Passive']['query'])
            misp_object = MISPObject('domain-ip')
            misp_object.add_attribute(itype, value)
            for record in dns_result['Passive']['records']:
                misp_object.add_attribute(ftype, record['value'])
            misp_object.add_reference(self.attribute.uuid, 'related-to')
            self.misp_event.add_object(**misp_object)

    def _parse_hash(self, value):
        malware_result = self._api_call(f'{self.base_url}/malware/{value}')
        if malware_result and malware_result.get('malware'):
            malware_report = malware_result['malware']
            for malware in malware_report.get('origins', {}).get('CnCServers', {}).get('rows', []):
                self._handle_file(malware, 'related-to')

    def _parse_ip(self, value):
        self._parse_dns(value)
        self._parse_malware(value, 'ipr')

    def _parse_malware(self, value, feature):
        malware_result = self._api_call(f'{self.base_url}/{feature}/malware/{value}')
        if malware_result and malware_result.get('malware'):
            for malware in malware_result['malware']:
                self._handle_file(malware, 'associated-with')

    def _parse_url(self, value):
        self._parse_dns(value)
        self._parse_malware(value, 'url')

    def _parse_vulnerability(self, value):
        vulnerability_result = self._api_call(f'{self.base_url}/vulnerabilities/search/{value}')
        if vulnerability_result:
            for vulnerability in vulnerability_result:
                misp_object = MISPObject('vulnerability')
                for code in vulnerability['stdcode']:
                    misp_object.add_attribute('id', code)
                for feature, relation in zip(('title', 'description', 'temporal_score'),
                                             ('summary', 'description', 'cvss-score')):
                    misp_object.add_attribute(relation, vulnerability[feature])
                for reference in vulnerability['references']:
                    misp_object.add_attribute('references', reference['link_target'])
                misp_object.add_reference(self.attribute.uuid, 'related-to')
                self.misp_event.add_object(**misp_object)


def handler(q=False):
    if q is False:
        return False
    request = json.loads(q)
    if not request.get('config') or not (request['config'].get('apikey') and request['config'].get('apipassword')):
        misperrors['error'] = 'An API authentication is required (key and password).'
        return misperrors
    key = request["config"]["apikey"]
    password = request['config']['apipassword']
    if not request.get('attribute') or not check_input_attribute(request['attribute']):
        return {'error': f'{standard_error_message} which should contain at least a type, a value and an uuid.'}
    if request['attribute']['type'] not in mispattributes['input']:
        return {'error': 'Unsupported attribute type.'}
    parser = XforceExchange(request['attribute'], key, password)
    parser.parse()
    return parser.get_result()


def introspection():
    return mispattributes


def version():
    moduleinfo['config'] = moduleconfig
    return moduleinfo