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
• 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)

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 [deprecated]

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

3. Mozilla Thunderbird [deprecated]

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?) 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.

1. Configure mail_to_misp_config.py

2. ln -s mail_to_misp_config.py fake_smtp_config.py

3. Run fake_smtp.py (as root)

$ sudo python3 fake_smtp.py

Apple Mail [deprecated]

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 [deprecated]

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 [deprecated]

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

General

• mail_to_misp requires access to a MISP instance (via API).
• Python 3
• dnspython
• 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://bitbucket.org/johannestaas/defang
• Patch defang/defang/init.py by commenting out the following line (not used && not compatible with Python 3): from urllib2 import urlparse
• Optionally patch defang/defang/init.py and add dirty_line = dirty_line.replace('hxxp', 'http') at line 47

Thunderbird [deprecated]

• 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 Sascha Rommelfangen
• Copyright (C) 2017 CIRCL - Computer Incident Response Center Luxembourg