mirror of https://github.com/MISP/mail_to_misp
439 lines
21 KiB
Python
439 lines
21 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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import re
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import syslog
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import html
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import os
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from io import BytesIO
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from ipaddress import ip_address
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from email import message_from_bytes, policy, message
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from . import urlmarker
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from . import hashmarker
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from pyfaup.faup import Faup
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from pymisp import ExpandedPyMISP, MISPEvent, MISPObject, MISPSighting, InvalidMISPObject
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from pymisp.tools import EMailObject, make_binary_objects, VTReportObject
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from defang import refang
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try:
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import dns.resolver
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HAS_DNS = True
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except ImportError:
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HAS_DNS = False
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def is_ip(address):
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try:
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ip_address(address)
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except ValueError:
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return False
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return True
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class Mail2MISP():
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def __init__(self, misp_url, misp_key, verifycert, config, offline=False, urlsonly=False):
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self.offline = offline
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if not self.offline:
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self.misp = ExpandedPyMISP(misp_url, misp_key, verifycert, debug=config.debug)
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self.config = config
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self.urlsonly = urlsonly
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if not hasattr(self.config, 'enable_dns'):
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setattr(self.config, 'enable_dns', True)
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if self.urlsonly is False:
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setattr(self.config, 'enable_dns', False)
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self.debug = self.config.debug
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self.config_from_email_body = {}
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if not hasattr(self.config, 'ignore_nullsize_attachments'):
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setattr(self.config, 'ignore_nullsize_attachments', False)
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self.ignore_nullsize_attachments = self.config.ignore_nullsize_attachments
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# Init Faup
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self.f = Faup()
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self.sightings_to_add = []
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def load_email(self, pseudofile):
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self.pseudofile = pseudofile
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self.original_mail = message_from_bytes(self.pseudofile.getvalue(), policy=policy.default)
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try:
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self.sender = self.original_mail.get('From')
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except:
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self.sender = "<unknown sender>"
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try:
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self.subject = self.original_mail.get('Subject')
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# Remove words from subject
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for removeword in self.config.removelist:
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self.subject = re.sub(removeword, "", self.subject).strip()
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except Exception as ex:
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self.subject = "<subject could not be retrieved>"
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if self.debug:
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syslog.syslog(ex)
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# Initialize the MISP event
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self.misp_event = MISPEvent()
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self.misp_event.info = f'{self.config.email_subject_prefix} - {self.subject}'
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self.misp_event.distribution = self.config.default_distribution
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self.misp_event.threat_level_id = self.config.default_threat_level
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self.misp_event.analysis = self.config.default_analysis
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def sighting(self, value, source):
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if self.offline:
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raise Exception('The script is running in offline mode, ')
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'''Add a sighting'''
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s = MISPSighting()
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s.from_dict(value=value, source=source)
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self.misp.add_sighting(s)
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def _find_inline_forward(self):
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'''Does the body contains a forwarded email?'''
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for identifier in self.config.forward_identifiers:
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if identifier in self.clean_email_body:
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self.clean_email_body, fw_email = self.clean_email_body.split(identifier)
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return self.forwarded_email(pseudofile=BytesIO(fw_email.encode()))
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def _find_attached_forward(self):
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forwarded_emails = []
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for attachment in self.original_mail.iter_attachments():
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try:
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attachment_content = attachment.get_content()
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except KeyError:
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# Attachment type has no handler
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continue
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# Search for email forwarded as attachment
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# I could have more than one, attaching everything.
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if isinstance(attachment_content, message.EmailMessage):
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forwarded_emails.append(self.forwarded_email(pseudofile=BytesIO(attachment_content.as_bytes())))
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else:
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if isinstance(attachment_content, str):
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attachment_content = attachment_content.encode()
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filename = attachment.get_filename()
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if not filename:
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filename = 'missing_filename'
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if self.config_from_email_body.get('attachment') == self.config.m2m_benign_attachment_keyword:
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# Attach sane file
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self.misp_event.add_attribute('attachment', value=filename, data=BytesIO(attachment_content))
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else:
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f_object, main_object, sections = make_binary_objects(pseudofile=BytesIO(attachment_content), filename=filename, standalone=False)
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self.misp_event.add_object(f_object)
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if main_object:
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self.misp_event.add_object(main_object)
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[self.misp_event.add_object(section) for section in sections]
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return forwarded_emails
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def email_from_spamtrap(self):
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'''The email comes from a spamtrap and should be attached as-is.'''
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raw_body = self.original_mail.get_body(preferencelist=('html', 'plain'))
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if raw_body:
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self.clean_email_body = html.unescape(raw_body.get_payload(decode=True).decode('utf8', 'surrogateescape'))
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else:
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self.clean_email_body = ''
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return self.forwarded_email(self.pseudofile)
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def forwarded_email(self, pseudofile: BytesIO):
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'''Extracts all possible indicators out of an email and create a MISP event out of it.
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* Gets all relevant Headers
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* Attach the body
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* Create MISP file objects (uses lief if possible)
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* Set all references
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'''
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email_object = EMailObject(pseudofile=pseudofile, attach_original_mail=True, standalone=False)
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if email_object.attachments:
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# Create file objects for the attachments
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for attachment_name, attachment in email_object.attachments:
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if not (self.ignore_nullsize_attachments == True and attachment.getbuffer().nbytes == 0):
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if not attachment_name:
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attachment_name = 'NameMissing.txt'
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if self.config_from_email_body.get('attachment') == self.config.m2m_benign_attachment_keyword:
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a = self.misp_event.add_attribute('attachment', value=attachment_name, data=attachment)
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email_object.add_reference(a.uuid, 'related-to', 'Email attachment')
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else:
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f_object, main_object, sections = make_binary_objects(pseudofile=attachment, filename=attachment_name, standalone=False)
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if self.config.vt_key:
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try:
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vt_object = VTReportObject(self.config.vt_key, f_object.get_attributes_by_relation('sha256')[0].value, standalone=False)
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self.misp_event.add_object(vt_object)
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f_object.add_reference(vt_object.uuid, 'analysed-with')
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except InvalidMISPObject as e:
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print(e)
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pass
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self.misp_event.add_object(f_object)
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if main_object:
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self.misp_event.add_object(main_object)
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for section in sections:
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self.misp_event.add_object(section)
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email_object.add_reference(f_object.uuid, 'related-to', 'Email attachment')
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self.process_body_iocs(email_object)
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if self.config.spamtrap or self.config.attach_original_mail or self.config_from_email_body.get('attach_original_mail'):
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self.misp_event.add_object(email_object)
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return email_object
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def process_email_body(self):
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mail_as_bytes = self.original_mail.get_body(preferencelist=('html', 'plain')).get_payload(decode=True)
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if mail_as_bytes:
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self.clean_email_body = html.unescape(mail_as_bytes.decode('utf8', 'surrogateescape'))
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# Check if there are config lines in the body & convert them to a python dictionary:
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# <config.body_config_prefix>:<key>:<value> => {<key>: <value>}
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self.config_from_email_body = {k.strip(): v.strip() for k, v in re.findall(f'{self.config.body_config_prefix}:(.*):(.*)', self.clean_email_body)}
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if self.config_from_email_body:
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# ... remove the config lines from the body
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self.clean_email_body = re.sub(rf'^{self.config.body_config_prefix}.*\n?', '',
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html.unescape(self.original_mail.get_body(preferencelist=('html', 'plain')).get_payload(decode=True).decode('utf8', 'surrogateescape')), flags=re.MULTILINE)
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# Check if autopublish key is present and valid
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if self.config_from_email_body.get('m2mkey') == self.config.m2m_key:
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if self.config_from_email_body.get('distribution') is not None:
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self.misp_event.distribution = self.config_from_email_body.get('distribution')
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if self.config_from_email_body.get('threat_level') is not None:
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self.misp_event.threat_level_id = self.config_from_email_body.get('threat_level')
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if self.config_from_email_body.get('analysis') is not None:
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self.misp_event.analysis = self.config_from_email_body.get('analysis')
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if self.config_from_email_body.get('publish'):
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self.misp_event.publish()
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self._find_inline_forward()
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else:
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self.clean_email_body = ''
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self._find_attached_forward()
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def process_body_iocs(self, email_object=None):
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if email_object:
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body = html.unescape(email_object.email.get_body(preferencelist=('html', 'plain')).get_payload(decode=True).decode('utf8', 'surrogateescape'))
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else:
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body = self.clean_email_body
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# Cleanup body content
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# Depending on the source of the mail, there is some cleanup to do. Ignore lines in body of message
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for ignoreline in self.config.ignorelist:
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body = re.sub(rf'^{ignoreline}.*\n?', '', body, flags=re.MULTILINE)
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# Remove everything after the stopword from the body
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body = body.split(self.config.stopword, 1)[0]
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# Add tags to the event if keywords are found in the mail
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for tag in self.config.tlptags:
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for alternativetag in self.config.tlptags[tag]:
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if alternativetag in body.lower():
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self.misp_event.add_tag(tag)
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# Prepare extraction of IOCs
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# Refang email data
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body = refang(body)
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# Extract and add hashes
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contains_hash = False
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for h in set(re.findall(hashmarker.MD5_REGEX, body)):
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contains_hash = True
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attribute = self.misp_event.add_attribute('md5', h, enforceWarninglist=self.config.enforcewarninglist)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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if self.config.sighting:
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self.sightings_to_add.append((h, self.config.sighting_source))
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for h in set(re.findall(hashmarker.SHA1_REGEX, body)):
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contains_hash = True
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attribute = self.misp_event.add_attribute('sha1', h, enforceWarninglist=self.config.enforcewarninglist)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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if self.config.sighting:
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self.sightings_to_add.append((h, self.config.sighting_source))
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for h in set(re.findall(hashmarker.SHA256_REGEX, body)):
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contains_hash = True
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attribute = self.misp_event.add_attribute('sha256', h, enforceWarninglist=self.config.enforcewarninglist)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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if self.config.sighting:
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self.sightings_to_add.append((h, self.config.sighting_source))
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if contains_hash:
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[self.misp_event.add_tag(tag) for tag in self.config.hash_only_tags]
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# # Extract network IOCs
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urllist = []
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urllist += re.findall(urlmarker.WEB_URL_REGEX, body)
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urllist += re.findall(urlmarker.IP_REGEX, body)
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if self.debug:
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syslog.syslog(str(urllist))
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hostname_processed = []
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# Add IOCs and expanded information to MISP
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for entry in set(urllist):
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ids_flag = True
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self.f.decode(entry)
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domainname = self.f.get_domain()
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if domainname in self.config.excludelist:
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# Ignore the entry
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continue
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hostname = self.f.get_host()
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scheme = self.f.get_scheme()
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if scheme:
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scheme = scheme
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resource_path = self.f.get_resource_path()
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if resource_path:
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resource_path = resource_path
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if self.debug:
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syslog.syslog(domainname)
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if domainname in self.config.internallist and self.urlsonly is False: # Add link to internal reference unless in urlsonly mode
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attribute = self.misp_event.add_attribute('link', entry, category='Internal reference',
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to_ids=False, enforceWarninglist=False)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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elif domainname in self.config.externallist or self.urlsonly is False: # External analysis
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attribute = self.misp_event.add_attribute('link', entry, category='External analysis',
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to_ids=False, enforceWarninglist=False)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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elif domainname in self.config.externallist or self.urlsonly: # External analysis
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if self.urlsonly:
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comment = self.subject + " (from: " + self.sender +")"
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else:
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comment = ""
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attribute = self.misp.add_attribute(self.urlsonly, {"type": 'link', "value": entry, "category": 'External analysis',
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"to_ids": False, "comment": comment})
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for tag in self.config.tlptags:
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for alternativetag in self.config.tlptags[tag]:
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if alternativetag in self.subject.lower():
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self.misp.tag(attribute["uuid"], tag)
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new_subject = comment.replace(alternativetag, '')
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self.misp.change_comment(attribute["uuid"], new_subject)
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else: # The URL is probably an indicator.
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comment = ""
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if (domainname in self.config.noidsflaglist) or (hostname in self.config.noidsflaglist):
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ids_flag = False
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comment = "Known host (mostly for connectivity test or IP lookup)"
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if self.debug:
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syslog.syslog(str(entry))
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if scheme:
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if is_ip(hostname):
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attribute = self.misp_event.add_attribute('url', entry, to_ids=False,
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enforceWarninglist=self.config.enforcewarninglist)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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else:
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if resource_path: # URL has path, ignore warning list
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attribute = self.misp_event.add_attribute('url', entry, to_ids=ids_flag,
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enforceWarninglist=False, comment=comment)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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else: # URL has no path
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attribute = self.misp_event.add_attribute('url', entry, to_ids=ids_flag,
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enforceWarninglist=self.config.enforcewarninglist, comment=comment)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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if self.config.sighting:
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self.sightings_to_add.append((entry, self.config.sighting_source))
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if hostname in hostname_processed:
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# Hostname already processed.
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continue
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hostname_processed.append(hostname)
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if self.config.sighting:
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self.sightings_to_add.append((hostname, self.config.sighting_source))
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if self.debug:
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syslog.syslog(hostname)
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comment = ''
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port = self.f.get_port()
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if port:
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port = port
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comment = f'on port: {port}'
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if is_ip(hostname):
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attribute = self.misp_event.add_attribute('ip-dst', hostname, to_ids=ids_flag,
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enforceWarninglist=self.config.enforcewarninglist,
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comment=comment)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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else:
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related_ips = []
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if HAS_DNS and self.config.enable_dns:
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try:
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syslog.syslog(hostname)
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for rdata in dns.resolver.query(hostname, 'A'):
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if self.debug:
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syslog.syslog(str(rdata))
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related_ips.append(rdata.to_text())
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except Exception as e:
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if self.debug:
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syslog.syslog(str(e))
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if related_ips:
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hip = MISPObject(name='ip-port')
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hip.add_attribute('hostname', value=hostname, to_ids=ids_flag,
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enforceWarninglist=self.config.enforcewarninglist, comment=comment)
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for ip in set(related_ips):
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hip.add_attribute('ip', type='ip-dst', value=ip, to_ids=False,
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enforceWarninglist=self.config.enforcewarninglist)
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self.misp_event.add_object(hip)
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if email_object:
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email_object.add_reference(hip.uuid, 'contains')
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else:
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if self.urlsonly is False:
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attribute = self.misp_event.add_attribute('hostname', value=hostname,
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to_ids=ids_flag, enforceWarninglist=self.config.enforcewarninglist,
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comment=comment)
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if email_object:
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email_object.add_reference(attribute.uuid, 'contains')
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def add_event(self):
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'''Add event on the remote MISP instance.'''
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# Add additional tags depending on others
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tags = []
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for tag in [t.name for t in self.misp_event.tags]:
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if self.config.dependingtags.get(tag):
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tags += self.config.dependingtags.get(tag)
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# Add additional tags according to configuration
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for malware in self.config.malwaretags:
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if malware.lower() in self.subject.lower():
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tags += self.config.malwaretags.get(malware)
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if tags:
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[self.misp_event.add_tag(tag) for tag in tags]
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has_tlp_tag = False
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for tag in [t.name for t in self.misp_event.tags]:
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if tag.lower().startswith('tlp'):
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has_tlp_tag = True
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if not has_tlp_tag:
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self.misp_event.add_tag(self.config.tlptag_default)
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if self.offline:
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return self.misp_event.to_json()
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event = self.misp.add_event(self.misp_event, pythonify=True)
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if self.config.sighting:
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for value, source in self.sightings_to_add:
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self.sighting(value, source)
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return event
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def get_attached_emails(self,pseudofile):
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if self.debug:
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syslog.syslog("get_attached_emails Job started.")
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forwarded_emails = []
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self.pseudofile = pseudofile
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self.original_mail = message_from_bytes(self.pseudofile.getvalue(), policy=policy.default)
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for attachment in self.original_mail.iter_attachments():
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attachment_content = attachment.get_content()
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filename = attachment.get_filename()
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if self.debug:
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syslog.syslog(f'get_attached_emails: filename = {filename}')
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# Search for email forwarded as attachment
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# I could have more than one, attaching everything.
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if isinstance(attachment, message.EmailMessage) and os.path.splitext(filename)[1] == '.eml':
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# all attachments are identified as message.EmailMessage so filtering on extension for now.
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forwarded_emails.append(BytesIO(attachment_content))
|
||
return forwarded_emails
|
||
|