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#### Combining a mailworm with GPG ####
#################### by R3s1stanc3 ####
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index:
1. Intro
2. Few Words About GPG
3. The Idea
4. Advantages
5. How The Worm Works
6. Conclusion


1. Intro

This  summer, the whistleblower Edward Snowden leaked secret documents,
showing  that  we  are all spied on, by the NSA. Due to these leaks, we
saw  a massive growth in users of encryption software, like GnuPG (GPG)
and  others.  I  started  thinking  about different types of crypto and
their problems (and in this case new toys for VXers).


2. Few Words About GPG

Most people may have heard of GPG/PGP. For those who don't, I'll give a
really  short explanation. GPG is a asymmetric encryption method, using
a  private  and  a  public  key. If somebody wants to send an encrypted 
message  to  you,  he  needs your public key. Only your private key can 
decrypt  messages  that  are  encrypted with your public key. (For more 
information,  read  the Wikipedia article [0]). The public key is given
to  everyone,  who  wants  to  send  you encrypted messages. One way of 
exchanging  public  keys  is by uploading them to keyservers. Everybody 
can  store  his/her public key on a keyserver and make it available for 
anyone. These keyservers are our target today.


3. The Idea

Many keyservers have a webfrontent, that allows you to search keys. So
I  got  the idea to search for random strings and recive the keys. The
URL to do so, looks something like this:
http://eu.pool.sks-keyservers.net/pks/lookup?search=<search_string>&op=get
Every  public key contains the email address of it's owner (if the key
is  used for mailing) and extracting that is really easy. So you could
crawl through keyservers and collect a huge amount of email addresses.
So,  why  not write a mail worm, that collects its victim addresses on
keyservers.  But  it gets better than just having many victims for the
worm.  You could use the keys, to encrypt the mails and that will have
a few other advantages.

4. Advantages

When thinking about the advantages of an worm, that sends encrypted
messages,  we  need  to  think  about why there are no big mailworm 
outbreaks anymore. There are a few reasons:
 - spam filters:
 	there is only a limited amount of messages, a worm can write.
	these can be easily detected by spam filters
 - online virus scans:
 	many mail provider scan every mail for viruses before sending
	them  to  the  user. Once a worm is detected, it won't spread
	anymore.
 - users learn to think
 	every  child knows, that you shouldn't open a mail attachment
	by a stranger :)

So, how do we circumvent these problems?
 - spam filters:
 	encrypted  messages  can't  be scaned by any filter. They are
	just  some  rubbish,  nobody  exept  the owner of the private
	key can read
 - online virus scans:
 	same  es  for  the  encrypted messages: how would you scan an
	encrypted file?
 - users learn to think:
 	this  is  the  point,  where  I can't speak for everyone, but
	for  me,  encrypted  mails  seem  way  more  trustworthy than
	unecnrypted   ones.  With  a  bit  SE,  many  people  can  be
	tricked into executing the attachment


5. How The Worm Works

This  is  more  of  a  POC  code.  It  doesn't  use any kind of social
engineering.  It  just recives one random public key from a keyserver,
extracts  the email address, encrypts one of two messages and attaches
an encrypted copy of itself to the mail. After generating the mail, it
is send to the owner of the key.


6. Conclusion

Maybe  we  will  see a cool new worm outbreak in the next time. If you
look  for  a more efficent way to search for keys and send the worm to
more than one victim, it may spread really wide.



[0] Wikipedia - PGP   https://en.wikipedia.org/wiki/Pretty_Good_Privacy


R3s1stanc3 [vxnetw0rk]								October, 2013
r3s1stanc3@riseup.net - http://r3s1stanc3.me
