misp-modules/misp_modules/modules/expansion/stairwell.py

import json
import re
import requests
from pymisp import MISPEvent, MISPObject
from . import check_input_attribute, checking_error, standard_error_message


misperrors = {
    'error': 'Error'
}
mispattributes = {
    'input': [
        'md5',
        'sha1',
        'sha256'
    ],
    'format': 'misp_standard'
}
moduleinfo = {
    'version': '0.1',
    'author': 'goodlandsecurity',
    'description': 'Enrich hash observables with the Stairwell API',
    'module-type': ['expansion']
}
moduleconfig = ["apikey"]


def parse_response(response: dict):
    attribute_mapping = {
        'environments': {'type': 'comment', 'object_relation': 'environment', 'distribution': 5},
        'imphash': {'type': 'imphash', 'object_relation': 'impash', 'distribution': 5},
        'magic': {'type': 'comment', 'object_relation': 'magic', 'distribution': 5},
        'malEval': {
            'probabilityBucket': {'type': 'comment', 'object_relation': 'malEval-probability', 'distribution': 5},
            'severity': {'type': 'comment', 'object_relation': 'malEval-severity', 'distribution': 5}
        },
        'md5': {'type': 'md5', 'object_relation': 'md5', 'distribution': 5},
        'mimeType': {'type': 'mime-type', 'object_relation': 'mime-type', 'distribution': 5},
        'sha1': {'type': 'sha1', 'object_relation': 'sha1', 'distribution': 5},
        'sha256': {'type': 'sha256', 'object_relation': 'sha256', 'distribution': 5},
        'shannonEntropy': {'type': 'float', 'object_relation': 'entropy', 'distribution': 5},
        'size': {'type': 'size-in-bytes', 'object_relation': 'size-in-bytes', 'distribution': 5},
        'stairwellFirstSeenTime': {'type': 'datetime', 'object_relation': 'stairwell-first-seen', 'distribution': 5},
        'tlsh': {'type': 'tlsh', 'object_relation': 'tlsh', 'distribution': 5},
        'yaraRuleMatches': {'type': 'text', 'object_relation': 'yara-rule-match', 'comment': 'matching Stairwell yara rule name', 'distribution': 5}
    }
    environments_mapping = {
        "NCS2SM-YHB2KT-SAFUDX-JC7F6WYA": "Florian's Open Rules",
        "VR9Z98-4KU7ZC-PCNFEG-FURQ66FW": "Jotti",
        "D7W6M6-BA9BS4-BQ23Z4-NKCNWQ96": "Malshare",
        "D4447Q-WJJL6P-W7ME89-WHXJK8TW": "Malware Bazaar",
        "XAKLND-DKWP3Z-56RL88-6XJ5NH46": "Pro Rules",
        "GMEELM-K226XF-F95XZL-7VEJFKZ6": "Public Samples",
        "5HEG8N-9T7UPG-8SZJ7T-2J4XSDC6": "RH-ISAC",
        "2NN2BJ-HDVQHS-49824H-2SEDBBLJ": "RH-ISAC Malware Sharing",
        "VCZTNF-8S76AK-LUU53W-2SWFFZWJ": "Stairwell Experimental Rules",
        "GEG6FU-MRARGF-TLTM6X-H6MGDT5E": "Stairwell Methodology Rules",
        "EB3DXY-3ZYFVH-6HNKJQ-GAPKHESS": "Stairwell OSINT Rules",
        "NQNJM6-5LSCAF-3MC5FJ-W8EKGW6N": "Stairwell Research Rules",
        "TT9GM5-JUMD8H-9828FL-GAW5NNXE": "stairwell-public-verdicts",
        "MKYSAR-3XN9MB-3VAK3R-888ZJUTJ": "Threat Report Feeds",
        "6HP5R3-ZM7DAN-RB4732-X6QPCJ36": "Virusshare",
        "TV6WCV-7Y79LE-BK79EY-C8GUEY46": "vxintel"
    }

    misp_event = MISPEvent()
    misp_object = MISPObject('stairwell')
    for feature, attribute in attribute_mapping.items():
        if feature in response.keys() and response[feature]:
            if feature == 'yaraRuleMatches':
                for rule in response[feature]:
                    env_pattern = r'\b[A-Z0-9]{6}-[A-Z0-9]{6}-[A-Z0-9]{6}-[A-Z0-9]{8}\b'
                    env = re.findall(env_pattern, rule.split('yaraRules/')[0])[0]
                    misp_attribute = {
                        'value': rule.split('yaraRules/')[1],
                        'comment': f'Rule from: {environments_mapping.get(env, "Unknown UUID!")}'
                    }
                    misp_attribute.update(attribute)
                    misp_object.add_attribute(**misp_attribute)
            elif feature == 'environments':
                for env in response[feature]:
                    misp_attribute = {
                        'value': environments_mapping.get(env, f'Unknown Environment: {env}'),
                        'comment': 'Hash observed in'
                    }
                    misp_attribute.update(attribute)
                    misp_object.add_attribute(**misp_attribute)
            elif feature == 'malEval':
                for attr in attribute:
                    misp_attribute = {'value': response[feature][attr]}
                    misp_attribute.update(attribute[attr])
                    misp_object.add_attribute(**misp_attribute)
            else:
                misp_attribute = {'value': response[feature]}
                misp_attribute.update(attribute)
                attr = misp_object.add_attribute(**misp_attribute)
                if feature in ('md5', 'sha1', 'sha256'):
                    for label in response['malEval']['labels']:
                        attr.add_tag(label)
    misp_event.add_object(**misp_object)

    event = json.loads(misp_event.to_json())
    results = {'Object': event['Object']}

    return {'results': results}


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'):
        misperrors['error'] = 'A Stairwell api key is required for this module!'
        return misperrors
    if not request.get('attribute') or not check_input_attribute(request['attribute'], requirements=('type', 'value')):
        misperrors['error'] = f'{standard_error_message}, {checking_error}.'
        return misperrors
    attribute = request['attribute']
    if attribute['type'] not in mispattributes['input']:
        misperrors['error'] = 'Unsupported attribute type!'
        return misperrors

    headers = {
        "Accept": "application/json",
        "Authorization": request['config']['apikey'],
        "User-Agent": f"misp-module {__file__} {moduleinfo['version']}"
    }
    url = f"https://app.stairwell.com/v1/objects/{attribute['value']}/metadata"
    response = requests.get(url=url, headers=headers).json()

    if response.get('code') == 16:  # bad auth
        return {'error': f"{response['message']} Is api key valid?"}
    elif response.get('code') == 5:  # not found
        return {'error': f"{attribute['type']}:{attribute['value']} {response['message']}"}
    elif response.get('code') == 2:  # encoding/hex: invalid byte
        return {'error': response['message']}
    elif response.get('code'):  # catchall for potential unforeseen errors
        return {'error': response['message'], 'code': response['code']}
    else:
        return parse_response(response)


def introspection():
    return mispattributes


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