mail_to_misp

Connect your mail infrastructure to MISP in order to create events based on the information contained within mails.

Features

• Extraction of URLs and IP addresses (and port numbers) from free text emails
• Extraction of hostnames from URLs
• Extraction of hashes (MD5, SHA1, SHA256)
• DNS expansion
• Custom filter list for lines containing specific words
• Subject filters
• Respecting TLP classification mentioned in free text (including optional spelling robustness)
• Refanging of URLs ('hxxp://...')
• Add tags automatically based on key words (configurable)
• Add tags automatically depending on the presence of other tags (configurable)
• Add tags automatically depending on presence of hashes (e.g. for automatic expansion)
• Ignore 'whitelisted' domains (configurable)
• Specify a stop word term to no further process input
• Configurable list of attributes not to enable the IDS flag
• Automatically create 'external analysis' links based on filter list (e.g. VirusTotal, malwr.com)
• Automatically create 'internal reference' links based on filter list
• Detection of forwarded messages
• Process attachments as malware samples or specify that they are processed as benign files (m2m_attachment_keyword)

You can send mails with attachments to mail_to_misp and tell it, to treat the attachment as a benign document (in contrast to the default behaviour: treating it as a malware sample). You need to set a keyword in the configuration: m2m_attachment_keyword = 'attachment:benign'

• Logging to syslog
• Remove "[tags]", "Re:" and "Fwd:" from subjects
• Optionally attach entire mail to event
• Contains now a fake-smtpd spamtrap which delivers IoCs/mails to MISP
• Automatically filter out attributes that are on a server side warning list (enforcewarninglist=True)
• Support for value sighting (sighting=True, sighting_source="YOUR_MAIL_TO_MISP_IDENTIFIER")
• Auto-publish when key:yourkey is specified in mail (configurable, m2m_key, m2m_auto_distribution) The m2m_key configuration is used to specify a secret only you and your users know. If you know the key, you can send a mail to your mail_to_misp instance, and when this key is present in the body of the message, it will automatically publish the event. So let's assume your config says: m2m_key = 'ABCDEFGHIJKLMN0PQRSTUVWXYZ' If you send a mail to mail_to_misp containing: key:ABCDEFGHIJKLMN0PQRSTUVWXYZ the event is automatically published. If you don't want to use this feature, just don't put it in the message body. The distribution is defined in the configuration as well: m2m_auto_distribution = '3' # 3 = All communities

For OSINT collection purposes (like collecting URLs to OSINT reports), you can tell mail_to_misp to only extract URLs (--urlsonly) and append them to a predefined MISP event (--event N). The subject of such a mail goes into the comment field of the value.

Example:

osinturlcollection: "|/path/to/mail_to_misp.py --urlsonly --event 12345 -"

Pass parameters in the email body

m2m:<parameter>:<Value>

# Examples
m2m:attachment:benign  # Email attachment considered benign (attachment in MISP, malware-sample by default)
m2m:attach_original_mail:1  # Attach the full original email to the MISP Event (may contain private information)

m2m:m2mkey:YOUSETYOURKEYHERE  # Key required for some actions
# The following key are ignored if M2M:m2mkey is invalid
m2m:distribution:<0-3,5> # Note: impossible to pass a sharing group yet.
m2m:threat_level:<0-2>
m2m:analysis:<0-3>
m2m:publish:1  # Autopublish

Implementation

The implemented workflow is mainly for mail servers like Postfix. Client side implementations exist but are no longer supported:

1. Postfix and others

Email -> mail_to_misp

2. Apple Mail [unmaintained]

Email -> Apple Mail -> Mail rule -> AppleScript -> mail_to_misp -> PyMISP -> MISP

3. Mozilla Thunderbird [unmaintained]

Email -> Thunderbird -> Mail rule -> filterscript -> thunderbird_wrapper -> mail_to_misp -> PyMISP -> MISP

Installation

Postfix (or other MTA) - preferred method

1. Setup a new email address in the aliases file (e.g. /etc/aliases) and configure the correct path:

misp_handler: "|/path/to/mail_to_misp.py -"

2. Rebuild the DB:

$ sudo newaliases

3. Configure mail_to_misp_config.py

You should now be able to send your IoC-containing mails to misp_handler@YOURDOMAIN.

Bonus: Fake-SMTPD spamtrap

If you want to process all incoming junk mails automatically and collect the contained information in a separate throw-away MISP instance, you could use the fake_smtp.py script. It listens on port 25, accepts all mails and pushes them through mail_to_misp to a MISP instance. It can also be configured to listen on an SSL port. (465)

1. Configure mail_to_misp_config.py

2. cp fake_smtp_config.py-example fake_smtp_config.py

3. Make port 25 accessible to normal users

$ sudo apt install authbind
$ sudo touch /etc/authbind/byport/25
$ sudo chown misp:misp /etc/authbind/byport/25
$ sudo chmod 770 /etc/authbind/byport/25

4. Run fake_smtp.py

$ python3 fake_smtp.py

Apple Mail [unmaintained]

1. Mail rule script

• git clone this repository
• open the AppleScript file MUA/Apple/Mail/MISP Mail Rule Action.txt in Apple's 'Script Editor'
• adjust the path to the python installation and location of the mail_to_misp.py script
• save it in ~/Library/Application Scripts/com.apple.mail/

2. Create a mail rule based on your needs, executing the AppleScript defined before
3. Configure mail_to_misp_config.py

Thunderbird [unmaintained]

1. Git clone https://github.com/rommelfs/filterscript and install plugin (instructions within the project description)
2. Mail rule script

• git clone this repository
• open the bash script MUA/Mozilla/Thunderbird/thunderbird_wrapper.sh and adujst the paths
• adjust the path to the python installation and location of the mail_to_misp.py script

3. Create a mail rule based on your needs, executing the thunderbird_wrapper.sh script
4. Configure mail_to_misp_config.py

You should be able to create MISP events now.

Outlook [unmaintained]

Outlook is not implemented due to lack of test environment. However, it should be feasible to do it this way:

import win32com.client
import pythoncom

class Handler_Class(object):
    def OnNewMailEx(self, receivedItemsIDs):
        for ID in receivedItemsIDs.split(","):
            # Microsoft.Office.Interop.Outlook _MailItem properties:
            # https://msdn.microsoft.com/en-us/library/microsoft.office.interop.outlook._mailitem_properties.aspx
            mailItem = outlook.Session.GetItemFromID(ID)
            print "Subj: " + mailItem.Subject
            print "Body: " + mailItem.Body.encode( 'ascii', 'ignore' )
            print "========"

outlook = win32com.client.DispatchWithEvents("Outlook.Application", Handler_Class)
pythoncom.PumpMessages()

(from: https://blog.matthewurch.ca/?p=236)

Obviously, you would like to filter mails based on subject or from address and pass subject and body to mail_to_misp.py in order to do something useful. Pull-requests welcome for actual implementations :)

Requirements

The easy way

pip install --user poetry

# Install other python requirements
poetry install -E fileobjects -E openioc -E virustotal -E email -E url

# Test if the script is working
./mail_to_misp.py -h

General

• mail_to_misp requires access to a MISP instance (via API).
• Python >=3.6
• dnspython
• PyMISP
• faup from https://github.com/stricaud/faup
• urlmarker from https://github.com/rcompton/ryancompton.net/blob/master/assets/praw_drugs/urlmarker.py (contained in this project)
• ftfy from https://github.com/LuminosoInsight/python-ftfy (to fix unicode text)
• defang from https://github.com/Rafiot/defang.git (fork of: https://bitbucket.org/johannestaas/defang)

Thunderbird [unmaintained]

• https://github.com/rommelfs/filterscript (modified fork from https://github.com/adamnew123456/filterscript)

License

This software is licensed under GNU Affero General Public License version 3

• Copyright (C) 2017 - 2019 Sascha Rommelfangen, Raphaël Vinot
• Copyright (C) 2017 - 2021 CIRCL - Computer Incident Response Center Luxembourg