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#!/usr/bin/env ruby
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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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#
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# This script cracks a half-lm challenge/response hash that uses a
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# a static challenge key. The idea is you use rainbow tables to
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# crack the first 7 chars and this script to complete a few remaining.
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# If the password is longer than 10 characters, this script will fail.
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#
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msfbase = __FILE__
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while File.symlink?(msfbase)
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  msfbase = File.expand_path(File.readlink(msfbase), File.dirname(msfbase))
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end
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$:.unshift(File.expand_path(File.join(File.dirname(msfbase), '..', '..', 'lib')))
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require 'msfenv'
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$:.unshift(ENV['MSF_LOCAL_LIB']) if ENV['MSF_LOCAL_LIB']
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require 'rex'
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def usage
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  $stderr.puts("\n" + "    Usage: #{$0} <options>\n" + $args.usage)
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  exit
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end
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def try(word,challenge)
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  buf = ::Rex::Proto::NTLM::Crypt.lanman_des(word, challenge)
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  buf.unpack("H*")[0]
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end
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hash = pass = chall = nil
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$args = Rex::Parser::Arguments.new(
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  "-n" => [ true,  "The encrypted LM hash to crack"                                    ],
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  "-p" => [ true,  "The decrypted LANMAN password for bytes 1-7"                      ],
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  "-s" => [ true,  "The server challenge (default value 1122334455667788)"            ],
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  "-h" => [ false, "Display this help information"                                      ])
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$args.parse(ARGV) { |opt, idx, val|
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  case opt
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    when "-n"
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      hash = val
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    when "-p"
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      pass = val
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    when "-s"
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      chall = val
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    when "-h"
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      usage
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    else
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      usage
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  end
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}
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if (not (hash and pass))
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  usage
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end
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if (not chall)
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  chall = ["1122334455667788"].pack("H*")
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else
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  if not chall =~ /^([a-fA-F0-9]{16})$/
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    $stderr.puts "[*] Server challenge must be exactly 16 bytes of hexadecimal"
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    exit
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  else
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    chall = [chall].pack("H*")
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  end
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end
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if(hash.length != 48)
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  $stderr.puts "[*] LANMAN should be exactly 48 bytes of hexadecimal"
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  exit
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end
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if(pass.length != 7)
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  $stderr.puts "[*] Cracked LANMAN password should be exactly 7 characters"
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  exit
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end
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pass = pass.upcase
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hash = hash.downcase
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cset = [*(1..255)].pack("C*").upcase.unpack("C*").uniq
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stime = Time.now.to_f
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puts "[*] Trying one character..."
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0.upto(cset.length-1) do |c1|
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  test = pass + cset[c1].chr
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  if(try(test, chall) == hash)
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    puts "[*] Cracked: #{test}"
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    exit
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  end
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end
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etime = Time.now.to_f - stime
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puts "[*] Trying two characters (eta: #{etime * cset.length} seconds)..."
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0.upto(cset.length-1) do |c1|
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0.upto(cset.length-1) do |c2|
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  test = pass + cset[c1].chr + cset[c2].chr
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  if(try(test, chall) == hash)
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    puts "[*] Cracked: #{test}"
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    exit
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  end
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end
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end
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puts "[*] Trying three characters (eta: #{etime * cset.length * cset.length} seconds)..."
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0.upto(cset.length-1) do |c1|
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0.upto(cset.length-1) do |c2|
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0.upto(cset.length-1) do |c3|
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  test = pass + cset[c1].chr + cset[c2].chr + cset[c3].chr
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  if(try(test, chall) == hash)
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    puts "[*] Cracked: #{test}"
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    exit
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  end
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end
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end
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end
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puts "[*] Trying four characters (eta: #{etime * cset.length * cset.length * cset.length} seconds)..."
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0.upto(cset.length-1) do |c1|
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0.upto(cset.length-1) do |c2|
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0.upto(cset.length-1) do |c3|
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0.upto(cset.length-1) do |c4|
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  test = pass + cset[c1].chr + cset[c2].chr + cset[c3].chr + cset[c4].chr
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  if(try(test, chall) == hash)
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    puts "[*] Cracked: #{test}"
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    exit
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  end
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end
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end
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end
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end
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