Extract Attachments (extachment) from Emails

Update 8APR15 - Works on .msg files now.

I wasn't going to write a blog post on this, but figured I would go ahead and share it anyway.

I often find myself searching VirusTotal for tag:email and checking out the various phishing emails that get posted to VT.

Well, today I had some of my Yara rules trigger on some various domains that I track in the To: line.

So I downloaded them and then I am left trying to pull out the attachments and decode them so I can perform analysis. That's when I saw the email module for Python and started playing around with it.

An hour or so later I came up with extachment.py (extract attachments). So far i've only tested it on 25 emails that I pulled down on VT and some test emails from Outlook for Mac. It works especially well under a controlled environment where you know you have legitimate eml files and not just an upload text file in VT marked with an email tag.

Having said that, if you run into any errors just let me know and i'll see what I can do to fix the code, or if you have any ideas on how to improve it i'm all ears.

Help

python extachment.py -h

usage: extachment.py [-h] [-p PATH] [-o OUT]
Attempt to parse the attachment from EML messages.
optional arguments:
-h, --help show this help message and exit
-p PATH, --path PATH Path to EML files.
-o OUT, --out OUT Path to write attachments to.

Here is a sample of the output

I print out the magic so you can get an idea of what the file is. Then I use the attachment name as the file name to save to so you get "real" names and proper extensions. If it's a simple text file you will get something like, "Could not process .DS_Store. Try manual extraction."

python extachment.py -p eml/ -o out/

*Could not process .DS_Store. Try manual extraction.
	Header of file: Bud1*

*Email Name: 04c275b76dabf0cff85119942429e266e09394a1f4b2e47d0459544ae14cf904
	Magic: {\rt
	Saved File as: BL Draft.doc*

*Email Name: 0beb40c866e815f000643064e8d3c2186dd1ca4ad60e3c4757795a56d39a85e5
	Magic: %PDF
	Saved File as: April invoice 963536.pdf*

*Email Name: 1aa085f82eee9b74f4f88b5af03d46a428e15647b99e3a2b73768c1960de0177
	Magic: {\rt
	Saved File as: Order.doc*

*Email Name: 21e6932ec611b3592811104f7e4165edc20ffb9d7c76a1060d597c3724e2c552
	Magic: {\rt
	Saved File as: bluegrill_bus_card.doc*

*Email Name: 2cb553ffe1c898a1b6a586d4c232262d47ae1d390c66581cddf1387303e8ceed
	Magic: {\rt
	Saved File as: Airwaybill#-258-85695.doc*

*Email Name: 423e753de0baad6fc755cb5a1118531ef21825883775c38b3ffdb76a7c360020
	Magic: {\rt
	Saved File as: PRODUCTION ORDER LIST.doc*

Directory listing of the output folder

  • 116TRAILDRIVER-3172015123PM.PDF
  • Purchase Order.doc
  • Purchase Order.zip
  • Airwaybill#-258-85695.doc
  • bluegrill_bus_card.doc
  • April invoice 415878.pdf
  • image003.png

Sample

xxd out/invoice7Q85M3KYN6YXOLRQOP.doc |head

0000000: 7b5c 7274 6631 5c61 6e73 695c 616e 7369  {\rtf1\ansi\ansi
0000010: 6370 6731 3235 315c 6465 6666 305c 6465  cpg1251\deff0\de
0000020: 666c 616e 6731 3034 397b 5c66 6f6e 7474  flang1049{\fontt
0000030: 626c 7b5c 6630 5c66 7377 6973 735c 6663  bl{\f0\fswiss\fc
0000040: 6861 7273 6574 3020 4172 6961 6c3b 7d7b  harset0 Arial;}{
0000050: 5c66 315c 6673 7769 7373 5c66 6368 6172  \f1\fswiss\fchar
0000060: 7365 7432 3034 7b5c 2a5c 666e 616d 6520  set204{\*\fname
0000070: 4172 6961 6c3b 7d41 7269 616c 2043 5952  Arial;}Arial CYR
0000080: 3b7d 7d0d 0a7b 5c2a 5c67 656e 6572 6174  ;}}..{\*\generat
0000090: 6f72 204d 7366 7465 6469 7420 352e 3431  or Msftedit 5.41

I added some support for parsing .msg files, which are in OLE2 structured storage file format.

OLE2

*Email Name: emails/Resume.msg
	Magic: %PDF
	Saved File as: Resume.pdf*

*Email Name: emails/Resume.msg
	Magic: �PNG
	Saved File as: DD744063-E192-47B2-98FA-36E554EF627A[193].png*

Hopefully it's useful. I sort of just started playing around and found that it could be useful so kept going. If there is a better tool let me know. I spent my time writing one vs. looking on Google.

You can download the code from my GitHub

If you find these posts useful and educational you can donate via PayPal.Me here: $1, $2, $3, $4, $5 or Custom.

Enjoy!