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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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class MetasploitModule < Msf::Auxiliary
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  include Msf::Auxiliary::Scanner
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  include Msf::Exploit::Remote::Tcp
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  def initialize
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    super(
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      'Name'           => 'Simple FTP Fuzzer',
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      'Description'    => %q{
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        This module will connect to a FTP server and perform pre- and post-authentication fuzzing
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      },
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      'Author'         => [ 'corelanc0d3r <peter.ve[at]corelan.be>', 'jduck' ],
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      'License'        => MSF_LICENSE
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      )
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    register_options(
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      [
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        Opt::RPORT(21),
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        OptInt.new('STARTATSTAGE', [ false, "Start at this test stage",1]),
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        OptInt.new('STEPSIZE', [ false, "Increase string size each iteration with this number of chars",10]),
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        OptInt.new('DELAY', [ false, "Delay between connections in seconds",1]),
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        OptInt.new('STARTSIZE', [ false, "Fuzzing string startsize",10]),
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        OptInt.new('ENDSIZE', [ false, "Fuzzing string endsize",20000]),
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        OptInt.new('STOPAFTER', [ false, "Stop after x number of consecutive errors",2]),
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        OptString.new('USER', [ false, "Username",'anonymous']),
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        OptString.new('PASS', [ false, "Password",'[email protected]']),
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        OptBool.new('FASTFUZZ', [ false, "Only fuzz with cyclic pattern",true]),
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        OptBool.new('CONNRESET', [ false, "Break on CONNRESET error",true]),
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      ])
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    @evilchars = [
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      'A','a','%s','%d','%n','%x','%p','-1','0','0xfffffffe','0xffffffff','A/','//','/..','//..',
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      'A%20','./A','.A',',A','A:','!A','&A','?A','\A','../A/','..?','//A:','\\A','{A','$A','A*',
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      'cmd','[email protected]','#A','A/../','~','~A','~A/','A`/','>A','<A','A%n','A../','.././','A../',
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      '....//','~?*/','.\../','\.//A','-%A','%Y','%H','/1','!','@','%','&','/?(*','*','(',')',
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      '`',',','~/','/.','\$:','/A~%n','=','=:;)}','1.2.','41414141','-1234','999999,','%00','+A',
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      '+123','..\'','??.','..\.\'','.../','1234123+',
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      '%Y%%Y%/','%FC%80%80%80%80%AE%FC%80%80%80%80%AE/','????/','\uff0e/','%%32%65%%32%65/',
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      '+B./','%%32%65%%32%65/','..%c0%af','..%e0%80%af','..%c1%9c'
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    ]
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    @commands = [
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      'ABOR','ACCT','ALLO','APPE','AUTH','CWD','CDUP','DELE','FEAT','HELP','HOST','LANG','LIST',
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      'MDTM','MKD','MLST','MODE','NLST','NLST -al','NOOP','OPTS','PASV','PORT','PROT','PWD','REIN',
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      'REST','RETR','RMD','RNFR','RNTO','SIZE','SITE','SITE CHMOD','SITE CHOWN','SITE EXEC','SITE MSG',
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      'SITE PSWD','SITE ZONE','SITE WHO','SMNT','STAT','STOR','STOU','STRU','SYST','TYPE','XCUP',
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      'XCRC','XCWD','XMKD','XPWD','XRMD'
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    ]
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    @emax = @evilchars.length
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    register_advanced_options(
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      [
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        OptString.new('FtpCommands', [ false, "Commands to fuzz at stages 4 and 5",@commands.join(" ")]),
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        OptBool.new('ExpandCrash', [ false, "Expand any crash strings",false]),
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    ])
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  end
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  def get_pkt
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    buf = sock.get_once(-1, 10)
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    vprint_status("[in ] #{buf.inspect}")
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    buf
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  end
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  def send_pkt(pkt, get_resp = false)
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    vprint_status("[out] #{pkt.inspect}")
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    sock.put(pkt)
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    get_pkt if get_resp
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  end
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  def process_phase(phase_num, phase_name, prepend = '', initial_cmds = [])
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    print_status("[Phase #{phase_num}] #{phase_name} - #{Time.now.localtime}")
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    ecount = 1
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    @evilchars.each do |evilstr|
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      if datastore['FASTFUZZ']
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        evilstr = "Cyclic"
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        @emax = 1
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      end
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      if (@stopprocess == false)
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        count = datastore['STARTSIZE']
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        print_status(" Character : #{evilstr} (#{ecount}/#{@emax})")
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        ecount += 1
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        while count <= datastore['ENDSIZE']
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          begin
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            connect
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            if datastore['FASTFUZZ']
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              evil = Rex::Text.pattern_create(count)
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            else
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              evil = evilstr * count
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            end
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            print_status("  -> Fuzzing size set to #{count} (#{prepend}#{evilstr})")
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            initial_cmds.each do |cmd|
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              send_pkt(cmd, true)
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            end
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            pkt = prepend + evil + "\r\n"
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            send_pkt(pkt, true)
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            sock.put("QUIT\r\n")
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            select(nil, nil, nil, datastore['DELAY'])
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            disconnect
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            count += datastore['STEPSIZE']
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          rescue ::Exception => e
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            @error_cnt += 1
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            print_status("Exception #{@error_cnt} of #{@nr_errors}")
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            if (e.class.name == 'Rex::ConnectionRefused') or (e.class.name == 'EOFError') or (e.class.name == 'Errno::ECONNRESET' and datastore['CONNRESET']) or (e.class.name == 'Errno::EPIPE')
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              if datastore['ExpandCrash']
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                print_status("Crash string : #{prepend}#{evil}")
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              else
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                print_status("Crash string : #{prepend}#{evilstr} x #{count}")
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              end
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              if @error_cnt >= @nr_errors
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                print_status("System does not respond - exiting now\n")
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                @stopprocess = true
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                print_error("Error: #{e.class} #{e} #{e.backtrace}\n")
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                return
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              else
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                print_status("Exception triggered, need #{@nr_errors - @error_cnt} more exception(s) before interrupting process")
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                select(nil,nil,nil,3)  #wait 3 seconds
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              end
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            end
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            if @error_cnt >= @nr_errors
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              count += datastore['STEPSIZE']
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              @error_cnt = 0
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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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  end
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  def ftp_commands
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    if datastore['FtpCommands'].to_s.upcase == "DEFAULT"
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      @commands
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    else
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      datastore['FtpCommands'].split(/[\s,]+/)
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    end
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  end
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  def run_host(ip)
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    startstage = datastore['STARTATSTAGE']
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    @nr_errors = datastore['STOPAFTER']
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    @error_cnt = 0
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    @stopprocess = false
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    if datastore['FASTFUZZ']
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      @evilchars = ['']
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    end
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    print_status("Connecting to host " + ip + " on port " + datastore['RPORT'].to_s)
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    if (startstage == 1)
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      process_phase(1, "Fuzzing without command")
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      startstage += 1
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    end
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    if (startstage == 2) and (@stopprocess == false)
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      process_phase(2, "Fuzzing USER", 'USER ')
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      startstage += 1
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    end
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    if (startstage == 3) and (@stopprocess == false)
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      process_phase(3, "Fuzzing PASS", 'PASS ',
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        [ "USER " + datastore['USER'] + "\r\n" ])
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      startstage += 1
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    end
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    if (startstage == 4)
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      print_status "[Phase 4] Fuzzing commands: #{ftp_commands.join(", ")}"
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      ftp_commands().each do |cmd|
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        if (@stopprocess == false)
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          process_phase(4, "Fuzzing command: #{cmd}", "#{cmd} ",
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            [
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              "USER " + datastore['USER'] + "\r\n",
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              "PASS " + datastore['PASS'] + "\r\n"
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            ])
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        end
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      end
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      # Don't progress into stage 5, it must be selected manually.
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      #startstage += 1
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    end
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    # Fuzz other commands, all command combinations in one session
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    if (startstage == 5)
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      print_status("[Phase 5] Fuzzing other commands (Part 2, #{Time.now.localtime}): #{ftp_commands.join(", ")}")
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      ftp_commands().each do |cmd|
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        if (@stopprocess == false)
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          ecount = 1
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          count = datastore['STARTSIZE']
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          print_status("Fuzzing command #{cmd} - #{Time.now.localtime}" )
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          connect
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          pkt = "USER " + datastore['USER'] + "\r\n"
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          send_pkt(pkt, true)
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          pkt = "PASS " + datastore['PASS'] + "\r\n"
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          send_pkt(pkt, true)
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          while count <= datastore['ENDSIZE']
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            print_status("  -> Fuzzing size set to #{count}")
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            begin
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              @evilchars.each do |evilstr|
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                if datastore['FASTFUZZ']
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                  evilstr = "Cyclic"
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                  evil = Rex::Text.pattern_create(count)
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                  @emax = 1
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                  ecount = 1
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                else
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                  evil = evilstr * count
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                end
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                print_status(" Command : #{cmd}, Character : #{evilstr} (#{ecount}/#{@emax})")
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                ecount += 1
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                pkt = cmd + " " + evil + "\r\n"
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                send_pkt(pkt, true)
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                select(nil, nil, nil, datastore['DELAY'])
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                @error_cnt = 0
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              end
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            rescue ::Exception => e
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              @error_cnt += 1
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              print_status("Exception #{@error_cnt} of #{@nr_errors}")
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              if (e.class.name == 'Rex::ConnectionRefused') or (e.class.name == 'EOFError') or (e.class.name == 'Errno::ECONNRESET' and datastore['CONNRESET']) or (e.class.name == 'Errno::EPIPE')
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                if @error_cnt >= @nr_errors
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                  print_status("System does not respond - exiting now\n")
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                  @stopprocess = true
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                  print_error("Error: #{e.class} #{e} #{e.backtrace}\n")
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                  return
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                else
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                  print_status("Exception triggered, need #{@nr_errors - @error_cnt} more exception(s) before interrupting process")
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                  select(nil,nil,nil,3)  #wait 3 seconds
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                end
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              end
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              if @error_cnt >= @nr_errors
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                @error_cnt = 0
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              end
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            end
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            count += datastore['STEPSIZE']
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          end
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          sock.put("QUIT\r\n")
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          select(nil, nil, nil, datastore['DELAY'])
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          disconnect
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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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